1. Introduction to CNC machining

Computer Numerical Control (CNC) machining has revolutionized manufacturing by making machining operations seem straightforward and efficient. This subtractive process involves removing layers of material from a job piece to produce customized parts using a variety of materials, such as metals, plastics, wood, glass, foam, and composites. CNC machining is particularly valuable in industries like telecommunications and aerospace, where higher tolerances are required.

Fig 1: Introduction to CNC machining

2. Importance of CNC Machining in Custom Parts Production

CNC machining has gained immense popularity in sectors such as automotive, aerospace, medical, manufacturing, and defense due to its numerous advantages:

(a) Optimal Productivity:

CNC machines are computerized, reducing reliance on manpower once set up is complete. This automation leads to higher productivity compared to other machining methods.

(b) Agile Technology:

CNC machines facilitate the production of sophisticated custom parts at a reasonable cost. They also allow for design changes based on customer requirements without significant expense.

(c) Fast Production:

The use of specialized software enables the rapid fabrication of customized parts, reducing manual labor and ensuring consistency for low-to-medium volume production.

(d) Cost-Effective:

Lower labor costs, increased productivity, and timely deliveries make CNC machining a cost-effective choice.

(e) Safer Production:

With minimal human interaction during the fabrication process, CNC machining ensures a safer production environment.

(f) Ideal for Prototyping

CNC machining excels in rapid prototyping, allowing designs to be tested on a small scale and refined before full-scale production.

(g) Compatible with Diverse Materials

CNC machines can work with various materials, including metals, plastics, ABS, ceramics, foam, wood, and composites.

(h) Maximizes Efficiency and Accuracy

CNC machining ensures high efficiency and accuracy, minimizing human error.

3. Understanding CNC Machining

For a visual explanation, refer to this video: https://www.youtube.com/embed/v4jwVdFsoGo

The step-by-step process of CNC machining involves:

1. Creating a CAD model with specifications like tolerance, construction lines, and threads.

2. Converting the CAD model into a CNC-compatible format using CAM tools such as AutoCAD or Fusion 360.

3. Starting the machining process by attaching the required cutting tools.

CNC machines use a microprocessor to control the tool, with G-code and M-code programming languages providing information about feed rate, spindle speed, cutting tool, and coolant flow. The machine's control unit processes this data, creates motion commands, and ensures accuracy through feedback signals.

Fig 2:Schematic Representation of control unit in CNC

There are various types of CNC machines, including milling machines, lathes, routers, plasma cutters, electric discharge machines, and laser cutters.

4. Key Considerations in CNC Machining

a. Material Selection for CNC Machining

The selection of materials impacts the whole process of machining; its entire lifecycle including prototyping, production, defects, repairs etc. Identifying the material requirements, exploring potential materials, and then choosing the most suitable material are key considerations in ensuring best product outcomes.

Bet-Fit CNC materials and their properties

The selection of the right material for CNC machining projects involves considering several important factors such as:

1) Application : Different application require different kinds of material properties. Some application may require high ductility, whereas some may require brittleness, some may require high strength, and some may require greater toughness and so on. Aluminum is used in the aerospace industry as it has high strength-to-weight ratio.

2) Operating conditions : Materials may react differently in different operation conditions such as temperature variations, exposure to chemicals, UV radiation, water contact, and flame resistance. Proper understanding of the effect of environment conditions with the materials is required.

3) Dimension / Tolerance : Industries like aerospace require dimensionally stable components with precise tolerances. The materials those are malleable, ductile, properties that make them machine-able are preferred in these industries.

4) Electrical Conductivity : Some applications may require the material to have high conductivity while some process may require them to have insulating properties. For excellent conductivity, materials like copper, silver can be used and for insulating properties, PTFE (polytetrafluoroethylene) may be chosen.

5) Physical Appearance : Some customers may prioritize the aesthetics of the finished production as their major requirement. Depending on your customer's desire, maintaining the physical appearance and focusing on secondary finishing operations may also be essential.

6) Cost : Whatever a customer is paying for the product, it should be worthwhile of their time and money. Materials with better properties and failure resistance are expensive. Careful evaluation of the toughness, strength, hardness, wear resistance, corrosion resistance etc. is necessary to determine if a material can serve as a cost-effective alternative.

7) Availability : Proper research regarding the availability of the materials is to be done before finalizing the material. A material can have everything your process requires, but if it is not available abundantly, that material has to be replaced with one that is available to you locally or in some easy, indirect ways.

b. Design Considerations for CNC Machining

1) Inner Edges : While dealing with inner edges, a vertical corner radius should be of at least 1/3rd of the cavity depth. Slightly larger corner radius results in higher surface finish quality.

2) Thin Walls : If the wall thickness is decreased, it causes the decrement of stiffness of material. This in turn causes vibrations to increase which results in higher errors. Recommended wall thickness values are

Materials	Wall Thickness
Metals	0.8mm
Plastics	1.5mm

3) Holes : According to design recommendations, flat-bottom holes should be avoided as much as possible. To make deeper holes, specialized drill bits (minimum diameter of 3 mm) are employed.

4) Smaller Features : Similar to the flat-bottom holes, micro-machining (process of creating cavities and holes having diameter of less than 2.5 mm) is recommended to be avoided unless absolutely required.

5) e) Chamfers & Fillets : Chamfer edges are recommended to be at a standard 45° angle unless some other angles are absolutely necessary. For fillets, the radius of interior fillets is recommended to be higher than 1/3rd of the depth of the cavity for preventing tool breakage.

c. Quality Control in CNC Machining

In order to maintain quality by ensuring the production of defect-free products, dimensional accuracy and quality, mitigating risks and costs, and enhancing productivity, quality control is of absolute importance that can be carried out using following processes.

1) Customer communication : In a manufacturing business, customers have to be our number one priority. Communicating with them about their needs and demands, keeping them happy with quick contact after receiving a customer inquiry and sending samples is a main requisite in this field.

2) Understand the design of the product : After receiving the CAD drawings, engineers responsible for CNC machining should thoroughly evaluate the design, understand the product specifications, and double check all the details before initiating manufacturing process.

3) Product and service : The machinist should keep in mind that the main goal is to provide the customers better and unique product with reasonable pricing. From the procurement process to inspection and testing, all procedures play important role in ensuring the top notch quality of the products and services.

4) Verification of purchased products : To detect the visible effects, the inspector inspects all purchased products.

5) Process inspection : Process inspection can occur at any point along the manufacturing and production cycle. It is done to assure quality and ensure timely delivery of finished orders.

6) Final inspection : During the final quality control (QC) inspection, only products that pass the final inspection procedure can be packaged and dispatched to the customers. Documentation of all the inspection and testing findings is done during this process.

4. Choosing a CNC Machining Service for Custom Parts

When selecting a CNC machining service, consider:

1) Cost and Turnaround Time : The service should fit within the project's budget and timeline.

2) Manufacturing Capability : Evaluate the vendor's history, customer reviews, and capabilities.

3) Communication : Ask potential vendors about their experience, turnaround times, materials, tools, and additional services.

4. Future Trends

a) Use of Plywood in Laser Cutting

Creation of geometric patterns and etch designs on wood is possible nowadays, all thanks to CNC laser cutting techniques that helps in maintaining the strength, flexibility and durability of milled wood.

Fig 4: Laser cutting wood

b) BoXYZ

BoXYZ machine is the one that combines two technologies of 3D printing and CNC machining. It is an all-in-one device that integrates a CNC mill, a laser engraver, and a 3D printer. Because of its versatility in work, it is tremendously growing in popularity.

Fig 5: BoXYZ machining

c) Machining Ice

Japan has started using CNC machines in order to create intricate sculptures out of ice. By converting vector information into G-code and M-code, CNC machines care now able to mill ice into detailed and beautiful shapes.

Fig 6: Ice machining

d) Machine Alerts on Smartphone

It is not necessary to watch the machining process to receive updates on where the process is at. A system has been developed in your smart phones that can send alerts through texts, emails. It is capable of sending the users real-time information about the condition and status of their machines.

5. Conclusion

CNC machining services have revolutionized the production of custom parts by offering unparalleled precision, speed, and versatility. This advanced technology empowers businesses and individuals to bring intricate designs to life with exceptional accuracy and efficiency. With the capability to work with a wide range of materials and provide extensive customization, CNC machining fosters innovation and facilitates the creation of high-quality, distinctive parts.

1. Introduction

Injection molding is a crucial manufacturing process in today's world, contributing to the production of a wide range of plastic products across various industries. Injection molding is a process of producing parts by injecting molten material into a mold. Injection molding uses a ram or screw-type plunger to force molten plastic or rubber material into a mold cavity and solidifies into the shape of the mold cavity. This process is widely used due to its high precision for complex shapes. However, there are defects that occur when molten plastic flows out of the mold during injection and solidifies. This defect, known as injection molding flash, degrades the final product's quality and requires additional steps to trim or remove the excess material. Injection molding flash is the thin layer of extruded excess material on the parting line or any other two dissimilar faces where the mold meets and forms a boundary. The removal of injection molding flash is crucial in today's plastic industries to ensure product quality and performance.

2. Understanding Injection Molding Flash

Injection molding flash, also known as flashing, is a defect in molding process which occurs when excess material, usually in a thin layer, attaches itself to the product, particularly along the parting line where two surfaces meet. This can also happen in other areas where different shapes of the mold converge. The causes of injection molding can range from incorrect flow rates and high pressures during injection to flaws in mold cavities or the equipment used. The other causes might be material viscosity, pressure, and speed variations.

Fig 1: Flash in injection molding (source :https://go4mould.com/flash-injection-molding)

Flash has a direct impact on both product quality and production efficiency. Its presence doesn’t only compromise the appearance of the product but also creates functional issues. The excess material in the product surface disrupts the intended design and dimension of the part. It also obstructs moving parts affecting its functionality. An additional process called de-flashing is required to minimize the flash occurrence. This involves cutting, grinding, and breaking to remove the excess material. Additional processes mean additional time and costs of production which leads to slower production rates.

Fig 2: Quality comparison due to flashing (source: https://guanxin-machinery.com/injection-molding-flash-trouble-shooting-and-the-remedies/)

3. Causes of Injection Molding Flash

Excessive injection pressure:

Excessive pressure is a significant factor leading to the occurrence of flashing in injection molding process. When the injection speed and pressure are too high, the molten plastic gets pressurized and forces its way between the mold surfaces. This leads to the creation of flash in the form of thin layer of excess material between the mold surfaces

Inadequate clamping force:

Inadequate clamping force is the key cause of the injection molding flash in most cases. When clamping force is not enough, molding halves don’t close completely. This creates gaps that allow the molten plastic to leak during the injection process. This leaked material solidifies at the parting line creating flashes. Also, uneven clamping force is also a major factor in the creation of flashes. Uneven clamping force means pressure imbalances within the mold cavity during the injection process. This imbalance permits the material to flow in the area of low clamping force as plastic tries to escape through the easiest route.

Mismatched mold halves:

An injection molding flash occurs when molten material escapes the mold cavity through the parting line. It occurs where the two halves of the injection mold separate to release the plastic part. If they're misaligned and mismatched, the gaps are formed enabling molten material to leak and form flash.

Wear and tear of the mold:

Repeated use and continuous operation of the mold over time leads to wear and tear in the mold. This creates misalignment and gaps at the parting line. The molded parts become less precise than the intended design. This kind of wear and tear permits the molten plastic to seep through the gaps during injection creating an undesired flash.

Fig 3: flash defect in toy (source: https://www.linkedin.com/pulse/12-injection-molding-defects-how-prevent-hem-mandy/)

4. Prevention and Remedies for Injection Molding Flash

Injection mold flashing is a significant concern in manufacturing process. Effective prevention of injection molding flash is necessary to ensures top product quality, higher production rate and cost savings production. This section will highlight the prevention method and remedies that manufacturers can adapt to avoid injection molding flash.

Proper maintenance of the mold:

The mold should be maintained at regular intervals to prevent flash. Proper inspection should be done over time to check if there are unwanted gaps and misalignments due to the wear and tear of the mold. Actions like cleaning and replacement of worn parts should be conducted to minimize the likelihood of flash formation.

Optimizing injection parameters:

The injection parameters like injection pressure and clamping force play a vital role in the injection process. Optimizing these parameters based on the specific material properties and part geometry can reduce the likelihood of flash occurrence and achieve uniform distribution of molten plastic. Also, the parameters like injection speed, pack and hold pressure, cooling time, gate design and location should be adequately maintained.

Ensuring precise mold halves alignment:

Misaligned mold halves create openings for the molten material to escape through it during the injection process. So, accurate alignment of mold halves is critical for flash prevention. Proper alignment means no openings in the parting line area preventing material leakage. This can be achieved using features like guide pins and bushings in the mold design, these components provide precise points of contact. Also, consistent temperature should be maintained to prevent differential in thermal expansion.

Regular Quality Checks and Testing:

Quality checks and testing is essential for the early detection and mitigation of flash-related issues. Regular checks and testing during and after the injection process can quickly identify flashes in products. Visual inspection, measurements, and other testing methods enable manufacturers to detect flash defects promptly and take immediate corrective actions.

The prevention and remedies for injection molding flash require a multifaceted approach. Along with the above methods, there are other factors to be considered to minimize the occurrence of flash like increasing viscosity of flash, adequate vent system, barrel and nozzle temperature, etc.

5. The Role of Technology in Preventing Injection Molding Flash

Advanced molding machines are essential in preventing injection molding flash in today’s world. These machines are equipped with precise control systems and automated features that enhance molding accuracy. They offer improved clamping force control, ensuring proper mold closure and reduced chances of flash occurrence. Additionally, these advanced machines incorporate advanced pressure and temperature sensors that aid in real-time monitoring and adjustment of molding conditions during injection. These advanced molding machines utilize advanced servo-motor technology to provide precise control over clamping force and injection speed.

Fig 4: HIDRIVE hybrid ALLROUNDER injection molding machine (source: https://www.arburg.com/en/product-world/injection-moulding-machines/hybrid-machines/)

Software plays a critical role in flash prevention by enabling precise control over molding parameters. Process monitoring software continuously tracks key variables such as temperature, pressure, and injection speed. Moreover, software-driven simulations and virtual prototyping help in designing molds that minimize flash risks.

The VHX Series 4K Digital Microscope, by KEYENCE, can measure highly accurate 3D shapes on the submicron order and profiles of defective parts using high-definition images. Even microscopic flashes from melted plastic can be quantitatively measured and inspected, even when they occur due to distortion in the mold or insufficient clamping force. The acquisition of detailed 3D information on the defective part can aid in quickly detecting the cause, allowing for preventive measures.

Fig 5: 3d measurement and display of flash (source :https://www.keyence.com/products/microscope/digital-microscope/industries/chemistry/molding-defects.jsp)

Fig 6: Profile measurement of flash (source: https://www.keyence.com/products/microscope/digital-microscope/industries/chemistry/molding-defects.jsp)

6. Conclusion

In modern manufacturing, injection molding flash is a persistent challenge that compromises product integrity and efficiency. This defect disrupts functionality of the intended product and requires additional processing steps. However, this challenge can be overcome by maintaining molds and optimizing parameters. The case studies above highlight the importance of design enhancements, parameter tuning, and quality control. Ultimately, this article reflects the harmonious collaboration between human expertise and technological innovation in the pursuit of flawless manufacturing outcomes.

1. Introduction

Plastic injection molding is one of the manufacturing processes that injects molten plastics into the mold and is used for large-volume production to produce thousands of identical items. Injection molding materials include thermoplastics, thermosetting plastics, metals, glasses, elastomers, etc. This manufacturing process is cost-effective while dealing with mass production as it is fast, accurate, and highly repeatable. It is used by countless manufacturers in the field of automotive, industries, consumer goods, packaging, and so on. It is considered to be a high-speed process as once a mold is fabricated, cycle time for each plastic ought to take as little as 30 seconds.

For a detailed understanding, watch this video: https://youtu.be/QeaZzjf4DBM

Fig 1: Plastic injection molding (source: https://predictabledesigns.com/introduction-to-injection-molding/)

An undercut is a feature that may or may not make the ejection of a part from the mold difficult. Power switch slots, teeth of a thread, and locking tabs are prime examples of undercuts that needs to be avoided until and unless the design is indispensable. It is true that special tooling can be used to safely eject the part from the mold even when an undercut is present. But this results in an increment of cost as well as the time frame of the project.

2. Understanding Undercuts

Fig 2: Undercut in molded part

Injection molding undercuts are the features that are not orthogonal to the mold parting line, preventing them from easily or impossible to be ejected from the mold in the direction of the mold opening. However, it also offers some benefits; the presence of undercuts in injection molding lessens or replaces the requirement of secondary processes or assembly. For example, threading into an injection molded part design introduces an undercut feature, simultaneously preventing the need to machine threads in the molded part. Also, undercuts are usually used in mold designs to add assembly features to the injection molded part for better fitting, eliminating the need for other finishing operations.

Fig 3: Various undercuts in plastic injection molding(Source: https://xcentricmold.com/undercuts-in-plastic-injection-molding/)

3. Impact of undercuts on mold design and product functionality

Fig 4: Undercuts (source: https://www.fictiv.com/articles/product-study-undercuts-in-injection-molding)

S.N.	Impact on Mold Design	Impact on Product Functionality
a)	Complexity: Undercuts add complexity, cost, and manufacturing time as they need sliders, lifters, or side actions to release the part without any kind of damage.	Part Design: Undercuts can limit the design possibilities, leading designers to make compromises in the product design to accommodate the molding process.
b)	Parting Line: Undercuts determine the position of the parting line (boundary where mold separates into two halves).	Assembly: Products with undercuts sometimes require more assembly steps, which may result in errors and inefficiency.
c)	Mold Material and Construction: Due to the complexity of undercuts, higher-grade materials and precision machining may be required.	Quality and Tolerance: Undercuts affect dimensional accuracy due to distortions when the part is released from the mold.
d)	Cycle Time: Undercuts may result in longer cycle times, reducing overall production output.	Strength and Structural Integrity: If undercuts create thin walls or intricate geometries, the overall strength and structural integrity of the molded part may diminish.

Undercuts are a challenging aspect of injection molding that requires careful consideration to balance design, cost, and functionality. By understanding their impacts on mold design and product functionality, manufacturers can make informed decisions to optimize the production process.

4. Types of Undercuts

Fig 5: Types of Undercuts (source: http://plasticlecturenotes.blogspot.com/2011/09/undercuts.html)

Undercuts can be of two types: external undercuts and internal undercuts.

(a) External Undercuts

These are featured on the outer surface of the molded part identified by grooves, indentations, or protrusions on the external surface of the part. For demolding and easy removal of parts with external undercuts, lateral moving elements like sliders (for simple undercuts), splits, and core pullers (for complex undercuts).

(b) Internal Undercuts

These are located on the inside contours of the molded part and are more challenging to deal with when compared to external undercuts since they consist of intricate geometries that cannot be dealt with by lateral movement alone; they need side actions or side pulls. But, even with side actions, the part may remain attached to the core which results in the need for further manual intervention or secondary processes.

5. Undercut Release Mechanisms

The dedicated techniques that are used in mold design to aid the smooth and efficient part removal from the mold cavity while still maintaining the integrity of the part and mold of a part with undercuts are called the undercut release mechanism. Some of the common undercut release mechanisms are side actions, lifters, core pullers, mold splits, hydraulic/mechanical actuators, and manual intervention. It is necessary to carefully analyze the geometry and requirement of material properties for that part to successfully select the most appropriate release mechanism. Proper selection as well as implementation of undercut release mechanisms is key to successful as well as cost-effective manufacturing processes that involve undercuts. The selection of the proper undercut release mechanism depends on:

• Design Complexity

• Type of undercuts

• Location of undercut

• Production volume

• Budget/cost constraints

6. Designing for Undercuts

(a) Challenges of undercutting injection molding

• Mold Complexity: Since, undercuts require the addition of slides, lifters, or core pullers; the design complexity is higher in mold design with undercuts.

• Draft Requirements: Draft angles should be reduced or kept zero while dealing with undercuts, which increases the challenge to obtain smooth part removal.

• Material Selection: Certain materials can stick or deform more during ejection, resulting in part damage, rejection, or increased scrap rates. Also, more issues generate with more rigid materials

• Parting Line Challenges: Inappropriate placement of parting lines can lead to poor material flow that leads to molding defects like voids, incomplete filling, sink marks, flash, or difficulty in the assembly of the molded parts.

• Increased Cycle Time: Undercuts can be ejected safely; however it requires additional steps like actuating side actions or lifters. This significantly increases the overall cycle time while also reducing production efficiency.

• Tooling Costs: As you know, the use of additional components and mechanisms to put up with undercuts means higher costs. They are usually expensive to maintain as well.

(b) Strategies for incorporating undercuts in design

• Position Parting Lines:

The parting line is the intersection plane between two molds which helps to solve the undercut problem if they are positioned properly. The reason behind this is: when the feature is divided into two halves by the parting line, the part can be easily ejected from the mold without having the need to include an undercut.

Fig 6: Parting Line Position

• Utilize Side-Actions Feature:

A side-action core is an insert that slides out of the part during the ejection of the part. This feature can be automated to slide in at the same rate as the other parts of the mold and retract when they retract. The molded part is available for extraction only once the side action has been completed which helps in proper extraction. The side action core needs to be perpendicular, and this critical requirement increases the complexity of the mold design.

Fig 7: Using side action core

• Use Bump Offs:

Bump offs are the best choice when dealing with elastic materials like lens covers, phone cases, etc. After the molding process is complete, this insert is removed first and then the main part is ejected normally. However, there are some restrictions while using this mechanism:

- The part must be flexible and elastic.

- The under feature must not be stiff features like corners and ribs.

- The lead angle must be between 300 and 450.

• Choose Hand-Loaded Inserts:

Hand-loaded inserts are different metal pieces that the operator manually places in the mold to prevent any plastic from flowing in. This facilitates the ejection process as the operator is free to remove the piece once the cycle is over and reuse it for the next batch. This is a manual process, which means that it’d naturally take more time to complete. Furthermore, the high temperatures involved create a safety concern as well. Workers use safety gloves and goggles but there is always a chance of burning yourself.

Fig 8: Hand loaded insert

• Incorporate Shutoffs:

If shutoffs are used, they can eliminate the need for side action or hand inserts, reducing the cost and increasing the production rate. These are temporary obstructions that use hooks, clips, etc. in order to snap-fit and prevent the flow in particular regions of the design.

• Lifters:

Fig 9: Using lifters

7. Role of software in designing for undercuts

(a) 3D Modeling and Visualization:

3D modeling software helps in creating the CAD model that helps in the visualization of parts to properly understand the complexities and challenges that can be resulted from undercuts. Then, they can plan their design strategies according to that.

(b) Draft Analysis:

Specialized software tools helps in draft analysis to ensure enough draft angles are created to aid smooth part removal.

(c) Mold Flow Analysis:

With mold flow analysis software, you can identify the flow issues that might occur and then you can alter your design strategies accordingly.

(d) Undercut Release Mechanism Simulation:

With the help of this software, you can assess the effectiveness of different mechanisms and then make the selection of one to ensure safe and effective part ejection.

(e) Toolpath Generation:

This software can create toolpaths for CNC machines that help to achieve precise mold geometry. These are specially used for machining complex mold features to facilitate their smooth part ejection.

8. Overcoming Undercut Challenges in Injection Molding

Collapsible cores and expandable cavities are specialized features that are used in undercut injection molding to ensure the safe ejection of parts.

9. Innovative solutions for undercut challenges

(a) Multi-Material Molding:

Successful ejection of parts with undercuts can be attained with the integration of different materials having varied levels of flexibility or shrinkage.

(b) Conformal Cooling:

Conformal cooling channels can improve the cooling process and check the sticking of parts with undercuts.

(c) Micro-Textured Surfaces:

To minimize friction and adhesion, micro-textured or nano-textured surfaces can be applied to mold components. It helps to ease the release of parts with undercuts. Similarly, these textured surfaces can reduce the requirement for complex release mechanisms.

(d) Magnetic Release Mechanism:

Ejection of the parts with undercuts can be promoted with the application of magnetic release mechanisms into molds. Parts can be released without the need for extensive side actions or lifters, by utilizing controlled magnetic forces.

(e) Smart Coatings and Lubricants:

Using specialized coatings or lubricants, friction can be reduced on mold surfaces to improve the release of parts with undercuts.

10. Conclusion

Summing up, despite the challenges that occur due to the presence of undercut in the mold design, proper understanding and management of undercut can lead to several benefits as well. With the proper parting line placement, the use of an appropriate release mechanism, and the use of advanced software, an undercut may prove its worth in the sense that it can be used to increase efficiency, and functionality while focusing on aesthetics. It wouldn't be wrong to say that proper play with the knowledge of undercut might even shape the future landscape of plastic injection molding.

1. Introduction

There is always some sort of imperfections on the mold surface due to various factors like injection molding parameters, different physical and chemical properties of the polymer blends, shrinkage, contamination, etc. That’s why most plastic product needs additional treatment to improve the surface finish. When it comes down to the aesthetic appeal of the product, surface finish becomes a critical aspect. Surface finish, also known as surface texture, is the overall texture of the surface determined by the three characteristics of lay, surface roughness, and waviness. Mold texturing is one of the crucial processes in manufacturing industries when producing parts made up of plastic, glass, metal, and ceramic through various molding techniques. The major advantages of mold texture are improved appearance, reduced creases, and enhanced grip. Along with the aesthetics, it also contributes to hiding imperfections like flow lines, sinks, burn scars, etc. Mold texturing also provides functional benefits like strength and enhanced adhesion to the product. The other benefits of mold texturing are improved mold release, branding, and the creation of parts that mimic natural materials like wood, rock, leather, etc. Trade associations like the Society of the Plastics Industry (SPI) and the Society of German Engineers/ Verein Deutscher Ingenieure (VDI) determine the standards and designation for the molding finish and textures. Mold-Tech (MT) and Yick Sang (YS) are the two companies that have developed their own standards

2. Understanding Mold Textures

Mold texturing is the process of creating various patterns, textures or designs on the product's surface. The purpose of mold texturing is to impart a distinct appearance to the final product during the molding process. The appearance can range from simple patterns like grains or dots to complex designs that mimic natural materials, such as wood, leather, or stone. Mold texturing plays a significant role in enhancing the visual appeal, functionality, and differentiation of molded products. Generally, Mold surface texturing is done by five common methods and they are:

(a) Sanding and Polishing

Machining operation always leaves behind some tool marks on the workpiece. So, these tool marks should be removed before transferring the workpiece to injection molding. Sanding and polishing are done to remove those marks and other surface imperfections by the technicians using rotary tools, sandpapers, and other abrasive papers. The factor to consider while sanding and polishing is not to exceed dimensional tolerances.

Fig 1: Sanding and Polishing (source : https://www.mirka.com/ , https://sandpaperamerica.com/)

(b) EDM Spark erosion

It uses graphite or copper electrode immersed in an electrolytic bath of water or oil. When the electrode receives its threshold current, it sparks against the tool wall. This process melts the targeted body and is immediately quenched by the surrounding electrolyte. Thermal shock is generated which causes the metal to fragment into tiny particles and they are flushed away. It is applicable for hard and soft metals which required very tight tolerances.

Fig 2: EDM(source : https://www.youtube.com/watch?v=9oPmFb4liVM&ab_channel=EDMPrecision)

(c) Media Blasting

High-pressure air sprays are used to transfer abrasive media (e.g., sand, beads) on molds, achieving a uniform matte or satin finish. It is controlled by skilled operators. This process is very fast, cost-effective, and minimal waste. It Allows distinct textures without overlap.

Fig 3: Media Blasting (source : https://www.cnclathing.com/guide/what-is-abrasive-blasting-or-sandblasting-cnclathing-metal-surface-finishing-services)

(d) Chemical photoetching

Photoetching applies patterns to mold tools by coating them with light-sensitive photoresist and then projecting desired patterns with UV light followed by etching in acid baths and creating textures. The process is fast, cost-effective, and fine details, but limited by undercuts and curved surfaces.

(e) Laser etching

Laser etching is the process that allows mapping textures onto curved surfaces using 3D computer modeling for precise alignment and 5-axis motion control for accurate tracking, even in undercuts. This method is very common in automobiles for consistent long-length patterns despite its higher costs and longer setup time.

3. Mold-tech (MT) mold textures

(a) History and background:

Standex Engraving Group, affiliated with Standex International Corp, is a prominent texture development enterprise. It was founded in 1955 and is headquartered in the US. Mold-Tech is a subsidiary of Standex group that has boasted 33 texturing facilities worldwide. Since entering the Chinese market in 2003, Mold-Tech China rapidly expanded, operating eight production facilities with advanced European and US equipment. Notable innovations include Digital Transfer Technology (DTT) for seamless patterns on larger molds, 5-axis laser engraving, and the Architexture Studio for exclusive texture designs. They serve various industries, including automotive, with partnerships with Volkswagen, BMW, Honda, and others. Mold-Tech China's ISO 9001:2015 certification further reinforces its leading position in the engraving industry, offering top-notch quality and after-sales service to renowned international enterprises.

(b) Overview of Mold-Tech Mold Textures

Standex Engraving Mold-Tech offers invaluable technical assistance and boasts the world's largest texture library with over 500,000 textures. Their Design Studio continually develops new textures, providing customized solutions to set products apart. Exclusive technology, like Render-Tech, enables seamless texturing on complex contoured surfaces. Mold-Tech emphasizes considerations for texture depth and draft, providing updated guidelines for optimal results. Their recommendation is 2 - 2.5 degrees of draft per .001” of texture depth

Fig 4: Draft angle and pattern depth for texture

They successfully work with various tooling materials and offer advanced etchants for successful texture application. Mold surface finish recommendations ensure flawless texture patterns. The team's expertise extends to gloss reduction techniques and welding procedures for textured surfaces. In case of texture damage, their experienced repair technicians offer solutions to rectify the impairment. Standard tool materials such as P-20, H-13, S-7, 01, A1, A2, A6, 420 stainless, beryllium copper, kirksite, and both forged and cast aluminum have all be all been textured successfully. Advanced etch testing is currently being conducted on new 3-D printed / laser-sintered metals. To ensure your texture pattern shows cleanly without surface flaws, Mold-tech recommends the following surface finish on all areas to be textured: 400 emery finish for textures less than .001” in depth. 320 emery finish for textures greater than .001” in depth. With skilled craftsmanship, global capacity, and technical expertise, Standex Engraving Mold-Tech is the trusted world leader in providing superior texturing services.

Fig 5: Mold-tech texture sample (source : Mold-Tech)

4. Unique Features and Benefits of Mold-Tech Mold Textures

• Chemical engraving: Standex Engraving's craftsmanship and advanced chemical engraving technology turn creative visions into reality. Seamlessly designed organic textures offer comfort, while precise patterns enhance functionality, providing limitless possibilities for distinctive product designs.
• Digital Transfer Technology (DTT): DTT guarantees consistency, pattern integrity, and texture harmony around the world. Exclusive to Standex Engraving Mold-Tech, DTT machines use a digital pattern sourced from a global library to print in high resolution directly onto molds for similar results.
• Laser Technology: Standex Engraving Mold-Tech is the exclusive global supplier of laser engraving, offering precise and sophisticated workmanship. Laser engraving provides superior features like multiple gloss levels, haptic touch effects, and optimized scratch performance. It allows flawless texture transitions, making it ideal for applications such as lens tooling that require jewelry-quality shimmer and brilliant results.
• Render-Tech: Render-Tech ensures textures fit every curve and turn flawlessly, maintaining proportion and dimension without any distortion, similar to a custom-tailored suit.

5. Yick Sang (YS) Mold Textures

History and Background

Yick Sang was established in 1981 in Hong Kong. YS is one of the pioneers of mold texturing in China. Their unwavering focus on innovation and quality has earned them international recognition as a one-stop solution for mold texturing. YS textures are widely identified globally, especially in the automobile and electronic industries. Yick Sang has expanded its growth across China, boasting over 20 facilities and a dedicated workforce of more than 500 employees in South, East, and West China. This strategic expansion enables them to efficiently meet their client's diverse demands.

Yick Sang's professional team is dedicated to delivering superior textures at competitive prices and catering to the specific requirements of its clients. Their commitment to excellence and customer satisfaction has grown their company as a trusted and renowned brand in the mold texturing industry. Through their years of experience and continuous pursuit of improvement, Yick Sang remains a reliable partner for high-quality mold texturing solutions worldwide.

Overview of Yick Sang Mold Textures

Yick Sang Mold Texture, backed by over 30 years of experience, excels in achieving precise textures for both simple and complex mold structures. Their skilled technicians offer a comprehensive range of texturing methods, including chemical etching, sandblasting, laser engraving, and more, ensuring high-quality and durable surface finishes. As a one-stop texture solution, Yick Sang caters to various industries, providing mold texturing for plastic injection molds and surface finishes for rollers or metal products. With their expertise and proficiency, Yick Sang is a trusted partner for clients seeking exceptional mold texturing services and superior surface finishes across a wide range of applications.

Fig 6: Yick Sang texture samples

6. Mold-Tech vs. Yick Sang: A Comparative Analysis

Comparison of Texture Variety and Options

Yick Sang texture books offer a collection of 240 texture plaques from basic plastic textures to mimicking materials like wood, leather, and floral patterns. In contrast, Mold-Tech offers a smaller range with 80 plaques. The Yick Sang Texture Book currently has three versions:

• 4 digits (YS1284) - Classic Version - 240 plaques
• 5 digits (YS20031) - Published in 2019 - 110 plaques
• 6 digits (YS300000) - Published in 2020 - 120 plaques

Mold-Tech texture specifications:

Yick Sang texture specifications:

For the Yick Sang catalogue, go through this link: Yick Sang Texture Catalogue

Comparison of Texture Quality and Durability

Mold-Tech and Yick Sang use similar methods for mold texturing to deliver reliable results. Both exhibit clear definitions and smooth finishes. However, Mold-Tech is more widely accepted for producing textures with a premium appearance, offering an extra level of finesse and visual appeal. Yick Sang textures, while generally more budget-friendly, provide a broader range of options and cost-effective solutions. The choice between Mold-Tech and Yick Sang depends on project requirements, design preferences, and objectives.

Comparison of Cost-Effectiveness

In terms of cost-effectiveness, Yick Sang is a more budget-friendly choice. Their textures match Mold-Tech's standards but are significantly cheaper, often 3 to 10 times less expensive. Yick Sang provides a more economical option while maintaining satisfactory results.

Comparison of Customer Service and Support

Mold-Tech excels in responsiveness and personalized assistance with a presence in 20 countries and a robust support system. Yick Sang, with a larger customer base, has slightly longer response times and a more limited global reach. While Yick Sang offers competitive services, Mold-Tech provides superior customer support and more extensive after-sales assistance.

7. Making the Right Choice: Factors to Consider

How to Choose Between Mold-Tech and Yick Sang Based on Project Requirements

• Budget: Consider your budget range. Mold-Tech textures are premium and costly, while Yick Sang offers economical options.
• Industry and Application: Depending on the project and application, Mold-Tech suits high-end industries, while Yick Sang caters to a broader range of products.
• Texture Complexity: Mold-Tech provides intricate textures, whereas Yick Sang offers versatility.
• Regional Availability: Accessibility to these companies may vary by location. Yick Sang is ideal for clients in Asia, while Mold-Tech serves a global market.

8. Conclusion

Mold texturing enhances the surface finish and aesthetics of molded parts. Mold-Tech offers a premium texture library with advanced technologies like DTT and laser engraving. Yick Sang provides cost-effective, high-quality textures for various industries. Both companies are reputable in the mold texturing industry, with Mold-Tech being a top choice for premium appearance and Yick Sang for budget-friendly options. The decision depends on industry needs, budget, project complexity, and regional availability.

1. Introduction

Over the past few decades, the injection molding process has evolved significantly more than almost any other manufacturing process and has influenced the development of numerous products. Injection molding consists of softening the material in a heated cylinder, injecting it into the mold cavity under pressure, and then hardening it by cooling. Injection molding technologies are mainly divided into two main categories: hot runner and cold runner mold systems. A hot runner mold is a system that heats the molds and runner channels to keep material in a molten state for the duration of the injection process until the mold cavity is filled, leaving no plastic inside the runners. In a cold runner system, the runners and the molds are not heated. The plastic fills the runners and mold cavities. The material then cools inside these cavities, which keeps the runners and parts connected until they are ejected and separated. Each of these systems has distinct advantages over the other. So, the choice between these two mold systems depends upon various factors like cost-effectiveness, material usage, material wastage, cycle times, and part quality.

2. Understanding Cold Runner Molds

Cold runner molds are the common type of injection molds that are being used for decades. It consists of two or three plates held within the base plate. In cold runner molds, molten plastic is conveyed into the mold cavity through unheated channels, known as runners. The runner is basically a delivery system that distributes the plastics to each cavity within the mold. The cold runner mold system is divided into two types: (i) two-plate system and (ii) three-plate system. The two-plate cold runner system consists of two plates with the stationary mold containing the sprue, runners, gate, and cavities. The runner is attached to the final product and should be cut off. In three-plate system, there is no need to cut the runner from the injection molded part, and the mold has a self-ejection system for part removal.

The working principle involves injecting molten plastic into the mold cavity through an unheated channel. First, the plastic is melted and then injected into the mold via a sprue connected to the runners. These runners guide the molten plastic to the mold cavities, ensuring uniform distribution of the material through gates. Then, the final part is formed, after the plastic cools and solidifies. In two-plate mold system, the runners and the part are not separated, requiring an ejection system to detach the molded component from the core half of the mold. In contrast, three-plate molds have a separate cavity plate that contains the runners. In three-plate system, there is no need for the separation of runners and the part, and doesn’t require an ejection system.

Fig 1: Cold runner mold and its types (source : https://www.myplasticmold.com/how-to-chose-correct-injection-mould.html)

Fig 1: Cold runner mold and its types (source :

Advantages

• Lower initial cost: The absence of a heated manifold system in cold runner molds makes it lower in initial cost compared to a hot runner system. Cold runner molds have a simpler design which makes it a budget-friendly option. Also, maintenance and repair costs are very low compared to the hot runner molds.
• Flexibility in material use: As the runners are unheated, there is no risk of heat degradation or pre-mature melting for heat-sensitive plastics. Whether it's commodity plastics like polyethylene, or engineering plastics like ABS or nylon, cold runner molds are feasible for these all materials in manufacturing.

Disadvantages

• Material waste: In each molding cycle, the unheated runners that are filled with molten plastic solidify along with the molded parts. When the part has to be ejected after each cycle, the solidified plastic at runners becomes unusable. This creates a major drawback when manufacturing on large scales. This results in a huge amount of material waste.
• Longer cycle times: Cold runner mold has longer cycle times compared to hot runner mold. In unheated runners, the cooling and solidification phase of the plastic takes a considerable amount of time, which slows down the overall manufacturing.

3. Understanding Hot Runner Molds

Nowadays, hot runner molds are the cutting-edge technology for injection molding. It consists of two plates that are heated through a manifold system. This manifold ensures that the plastic remains in a molten state until it flows into the cavity of the mold. Hot runner molds are categorized into two types, and they are insulated hot runners and heated hot runners. Insulated hot runner molds have extremely thick runners in the mold plate, which causes part of the molten plastic to cool down and insulate the system. This insulation results in reduced heat loss and allows the mold system to maintain an open plastic flow. Heated hot runner is further divided into two types: externally heated and internally heated molds. In externally heated molds, rods, coils, or pipes are used to heat the plates from outside of the mold. This type of mold is suitable for materials that are sensitive to thermal variations like polymers. On the other hand, internally heated mold has a heating component inside of the mold which leads to a drop in injection pressure. Also, it offers better flow due to the heated runner and gate tip control.

Fig 3: hot runner mold (source : https://www.myplasticmold.com/how-to-chose-correct-injection-mould.html)

Fig 4: hot runner mold system (source : https://www.echosupply.com/blog/injection-molding-basics-hot-runner-systems/)

Advantages

• No material waste: Hot runner mold eliminates the need for the runners in their molding process and this results in the complete elimination of wastage due to solidified runners.
• Faster cycle times: They offer faster cycle times than cold runner molds. The molten plastic is continuously supplied to the mold cavities, allowing for quicker filling and cooling which saves lots of time. This advantage makes them a suitable choice for high-volume production businesses.

Disadvantages

• Higher initial cost: One of the major drawbacks of the hot runner mold system is their higher initial cost as it requires manifold, heating components, and nozzles, to maintain the plastic in a molten state throughout the process. The additional components and technology involved in hot runner systems contribute to increased upfront investment.
• Limited in material use: Some plastics are sensitive to high temperatures, and longer exposure to heat in hot runner molds can lead to material degradation or undesirable changes in the plastic properties. Heat-sensitive polymers like thermally unstable resins might not be suitable for use in hot runner molds.

4. Comparison between Cold Runner Molds and Hot Runner Molds

Cost effectiveness

Hot runner systems require a higher initial investment and maintenance cost due to their complexity, including manifold systems, heating components, and nozzles. The reduced cycle time enhances efficiency and output rates, offsetting the initial investment over time. In contrast, cold runner mold systems have a lower tooling cost which makes them more economical for small-scale production and prototyping. The absence of a manifold system simplifies the design and lowers expenses. That’s why the cold runner system gets a cutting edge over the hot runner system on the basis of cost-effectiveness. Nonetheless, cold runner molds result in significant material wastage due to solidified plastics at runners and gates, making them less cost-effective for long-term and large-scale production.

Production speed

Hot runner molds system is faster in production speed compared to cold runner molds. The streamlined design of hot runner mold systems eliminates the runner removal process which enables faster filling and cooling of parts. On the other hand, cold runner molds consist of additional steps of separating, grinding, and recycling runners which leads to slower production. While hot runner systems may require a higher initial investment, their ability to produce more parts per unit of time makes them a preferred choice for manufacturers seeking increased production efficiency and output rates.

Materials use

Cold runner molds are superior to hot runner molds in terms of material varieties that can be used in the molding process. Some thermoplastic materials like thermal-sensitive resin or polymers are particularly sensitive to temperature variation. The heat in a hot mold system creates negative impacts on the mechanical properties of these materials. Cold runners don’t have any heating component which makes them more compatible with a wide range of thermoplastic materials.

Quality of final product

Hot runner molds offer superior final product quality than cold runner molds. The hot runner system delivers an excellent filling profile with consistent injection pressure to manufacture well-formed and defect-free parts. In contrast, cold runner molds have to go through injection pressure drop due to heat transfer to the mold plates during plastic flow. This leads to shrinkage and the formation of sink marks and under-filled parts.

Attributes	Hot Runner	Cold Runner
Allows quick changes in design or color	No	Yes
The high degree of tolerance	Yes	No
Works with a variety of thermoplastics	No	Yes
High maintenance cost	Yes	No
Produces large volumes of parts	Yes	No
Uses unheated runner	No	Yes
Molten thermoplastic or polymer is used	Yes	Yes

5. Case Studies

Fig 5: Cold runner vs Hot runner (source : https://www.hitcontrols.com/hot-runner-v-s-cold-runner/)

As you know, both cold runner molds and hot runner molds have their strengths and weaknesses. Therefore, the choice between the two depends on the part complexity, production volume, material characteristics, and cost considerations. Let's look at some examples of successful use for both types:

Successful Use of Cold Runner Molds in Industry

• Food Packaging industry to produce plastic food containers, trays, disposable cutlery, utensils bottle caps, and packaging components in an economical way.
• Building and Construction to manufacture plastic parts such as pipes, fittings, and construction elements like brackets and fasteners.
• Toys industry to produce plastic toys, playground equipment, and recreational items.
• Produces household goods such as storage containers, household tools, and cleaning equipment.
• Medical industry to produce certain medical-grade plastics as well as specialized engineering resins.
• Automotive industry to manufacture interior components like dashboards, door panels, seat trims, automotive bumpers, large containers, and appliance components.

Successful Use of Hot Runner Molds in Industry

The ability to control the molten plastic flow, minimize gate marks, and reduce material waste makes hot runner molds a popular choice in a wide range of industries, especially when producing high-value, intricate, and complex parts.

• Produce electrical components like closures, connectors, and small precision components due to the ability of hot runner systems to ensure tight tolerances, resulting in optimal electrical performance.
• Medical Devices and Instruments including syringes, IV components, and surgical instruments where hot runners ensure the production of sterile, defect-free parts.
• Cosmetic industry to produce packaging components such as lipstick cases, compact cases, and mascara containers.
• Automotive lighting components, including headlamp housings, taillight lenses, and signal indicators.
• Household appliances such as microwave parts, washing machine components, and vacuum cleaner parts.
• High-End consumer products like smart phones, high-quality audio equipment, and luxury goods.

6. How to Choose Between Cold Runner and Hot Runner Molds

There is no perfect answer as the choice depends on several factors like production needs, material and cost. Larger and more complex parts benefit from hot runner systems due to reduced material waste, cycle time, and quality issues. Whereas, smaller parts benefit from cold runner systems as they require less material and energy. The injection molding industry generally makes the decision to use a hot runner without considering a cold runner’s possible cost and quality benefits. It is true that hot runners require less material, less cost; however, they can create more scrap because of downtime and leaks. Choosing between cold runner and hot runner molds requires careful consideration of various factors related to production needs, material type, and cost considerations.

1. Assessing Production Needs:

SN	Needs	Hot runner molds	Cold runner molds
1)	Part complexity	Hot runner molds for intricate, complex parts with multiple gates.	Cold runner molds for simpler designs with a single gate.
2)	Production volume	For high-volume production, hot runner is cost-effective in the long run due to reduced material waste.	For low-volume production, cold runner molds are more economical.
3)	Cycle time	Hot runner molds offer faster injection and cooling cycles that helps in meeting tight production schedules.	Cold runner molds reduce downtime during maintenance, resulting in increased productivity and reduced production interruptions.

2. Considering Material Type:

• Material Sensitivity: Materials that are sensitive to heat and shear prefer cold runner molds in order to minimize the chances of material degradation. Hot runner is fitting for materials that can withstand the higher temperatures.
• Material Flow and Viscosity: Hot runner molds are suitable for materials with higher viscosity whereas cold runner molds can still work with materials with adequate flow properties and lower viscosity.
• Material Compatibility with Mold Components: For materials with high abrasive qualities, hot runner molds ensure longer mold lifespan and consistent performance. For materials that cause less wear on the mold's components, cold runner molds are appropriate.

3. Evaluating Cost Factors:

• Initial Investment: Cold runner molds are less expensive to manufacture and purchase, while hot runner molds have a higher initial cost due to the complexity of the system.
• Production Costs: Hot runner molds can lead to lower production costs in high-volume scenarios due to reduced material wastage and faster cycles.
• Tooling Maintenance: Cold runner molds are generally simpler and easier to maintain, while hot runner molds might require more specialized maintenance.

7. Conclusion

The correct choice between cold runner and hot runner molds is vital in determining production efficiency and part quality. Cold runner molds being a cost-effective solution for low-volume production of simpler part designs and hot runner molds excelling in high-volume production with faster cycle times and minimal material wastage, it is essential to assess your needs and then make a selection between these two. All-in-all, the key to getting the finest results and satisfying the requirements of various sectors and applications is to choose molds carefully.

1. Introduction

By injecting molten material into a mold, the industrial method of injection molding enables the fabrication of parts in huge quantities. The substance, which is often a thermoplastic or thermosetting polymer, is heated, mixed, and then pressed into a mold cavity, where it cools and solidifies into the mold's form. The success of injection molding depends on selecting the proper type of mold since it influences the product's quality, cost, and manufacturing efficiency. Molds may be divided into many sorts according to the quantity and nature of the cavities they hold. Multi-cavity molds and family molds are two prevalent forms of mold.

Fig 1: Major parts of Injection molding machine (Source: https://www.custompartnet.com/wu/InjectionMolding)

A single injection molding cycle can produce many pieces of the same type using multi-cavity molds. Those molds have multiple identical cavities. For example, to make several bottle caps simultaneously, a multi-cavity mold can be used. Multi-cavity molds include several benefits such as shorter cycle time, cheaper cost per part, and greater design parts. Family molds contain a variety of cavities which allow the manufacturing of several related items of different types. This can be achieved in a single injection molding cycle. For instance, using family molds body and four wheels of toy automobiles can be created simultaneously. With family mold lower tooling cost and production effectiveness can be achieved.

2. Understanding Multi-Cavity Injection Molds

Injection molds with several identical cavities, or multi-cavity injection molds, enable manufacturing numerous pieces of the same type within a single injection molding cycle. A multi-cavity mold, for instance, may make four bottle caps at once. Multi-cavity injection molds operate similarly to single-cavity molds, with the exception that a runner system uniformly distributes the molten material throughout the many cavities. According to the material and mold design, the runner system, which comprises passages connecting the injection nozzle to the cavities, can be either cold or hot.

Fig 2: multi-cavity injection mold (Source: https://www.kaso.com/everything-you-need-to-know-about-multi-cavity-injection-molds/)

Multi-cavity injection molds have a higher production rate as they can manufacture more components each cycle than single-cavity molds. In terms of large-scale manufacturing, this method is cost-effective because of lower cost per item, energy use, labor cost, and machine wear. As this method can provide consistent cooling, filling, and pressure across cavities, the uniformity and quality of the parts can be enhanced. Multi-cavity injection molds do, however, have significant drawbacks that must be taken into account. They need more intricate mold design, production, and maintenance than single-cavity molds, which results in several drawbacks, one of which is that they have a high initial cost. Due to its ability to only generate components of the same size, shape, and material, multi-cavity injection molds also have restricted design freedom. Injection molds with several cavities can also provide certain technical difficulties, such as balancing the runner system, managing mold temperature, and avoiding parting line and flash problems.

3. Understanding Family Injection Molds

Family injection molds are molds utilized in the process of injection molding to produce parts or components at the same time. Designers create these molds to accommodate cavities or impressions within a mold allowing for the production of different elements, in a single molding cycle. The use of family injection molds brings both advantages and disadvantages, which depend on the production requirements and complexity of part designs.

Fig 3: Family molds with two cases halve (Source: https://www.injection-moldings.com/groups/engineering-team/family-molds-benefits)

One notable advantage of family injection molds is their ability to produce parts simultaneously offering flexibility, in manufacturing. This not only helps reduce tooling costs but also enhances production efficiency while facilitating modifications to individual components. Family injection molds are particularly well suited for low-volume production scenarios involving varied parts that demand variations or components for a specific assembly. One drawback of using family injection molds is the potential for imbalances in filling, pressure, and cooling among the cavities. These imbalances can have an impact on the quality and consistency of the parts resulting in defects, like warping, shrinkage, flash, or short shots. It's important to note that family injection molds are best suited for parts that can be molded under conditions, including material type, temperature requirements, cycle time, and clamping force.

4. Comparison between Multi-cavity Injection Molds and Family Injection Molds

Based on production requirements and needs, family injection and cavity injection molds have discrete benefits and drawbacks. In this section, two molds types will be compared in terms of production rate, cost efficiency, adaptability, and quality assurance.

1. Production rate

Due to their ability to create more pieces each cycle than family injection molds, multi-cavity injection molds have a greater production rate. As a result, the injection molding process becomes more productive and efficient while cutting down on cycle time. For instance, whereas a family mold may simultaneously make one bottle cap and one bottle body, a multi-cavity mold can produce four bottle caps at once. In terms of production rate, the family injection mold can create fewer components in each cycle compared to multi-cavity molds. Family injection molds offer versatility in making several pieces simultaneously, resulting in less material use in optimum time. For low-volume manufacture of intricate and varied parts with the need for a variety of modifications, family injection molds are considered suitable.

2. Cost-effectiveness

In large-scale manufacturing, multi-cavity injection molds are more cost-effective than family injection molds because they may reduce the cost per item by cutting back on material waste, energy use, labor costs, and machine wear. However, since they require more intricate mold design, manufacturing, and maintenance than family injection molds, multi-cavity injection molds have a greater starting cost than family injection molds. In small-scale manufacturing, family injection molds are more cost-effective than multi-cavity injection molds because they may cut tooling costs by including numerous pieces into a single mold. Family injection molds, however, cost more per component than multi-cavity injection molds because they prolong cycle times and result in more material waste, energy use, labor costs, and machine wear.

3. Flexibility

In terms of part design and variation, multi-cavity injection molds are less flexible than family injection molds. The only pieces that multi-cavity injection molds can create are identically sized, shaped, and made of materials. This restricts the use of multi-cavity injection molds for the production of novel items or the customization of already existing products. Furthermore, once created, multi-cavity injection molds are challenging to replace or adjust since any change might compromise the mold's performance and balance. In terms of part design and variation, family injection molds are more flexible than multi-cavity injection molds. Family injection molds may create components in a variety of sizes, shapes, and materials. This enables the use of family injection molds to produce new items or modify ones that already exist. Family injection molds may also be changed or modified more easily once they are created since each cavity can be switched out or replaced without impacting the others.

4. Quality control

In terms of component consistency and homogeneity, multi-cavity injection molds have greater quality control than family injection molds. Injection molds with many cavities may maintain consistent component quality and dimensions by ensuring that each cavity receives the same amount of cooling, filling, and pressure. By maximizing the mold design and process parameters, multi-cavity injection molds can reduce part defects and imperfections. Family injection molds have less control over quality and consistency than multi-cavity injection molds. Variations in the size, shape, and material of the cavities may affect the final components' quality and uniformity. To guarantee high-quality components, family injection molds must be carefully designed and managed to address issues such as imbalances in filling, cooling, and pressure.

5. Comparison Summary

The table below sums up the key differences between multi-cavity and family molds.

Aspect	Multi-cavity Molds	Family Molds
Production rate	Great for speeding up production by making parts at the same time which helps reduce lead times, especially for high-volume manufacturing.	Can significantly reduce the assembly time by creating all associated parts together.
Cost-effectiveness	The initial investment for tooling can be quite high. It has the potential to lower the cost per part as the production volume rises.	The costs of tooling can be high. It helps avoid the need to create molds for each part.
Part quality	Offers a higher level of quality control and consistency among the parts produced.	Quality control may be less precise, potentially leading to variations in the parts.

6. How to Choose Between Multi-cavity Injection Molds and Family Injection Molds

a. Assessing Production Needs

Assessing your manufacturing requirements, including the quantity, speed, and complexity of your products, is the first stage. Multi-cavity injection molds are a good choice if you need to make a lot of basic, homogenous parts with few changes at a greater production rate, reduced cost per part, and consistent component quality. Family injection molds are a good choice if you need to create small quantities of intricate and varied parts that need several variants or components for a certain assembly since they may save tooling costs, increase production efficiency, and make part changes easier.

b. Considering Design Complexity

Consider the form, size, material, and look of your pieces, as well as their design complexity, in the second phase. You could use multi-cavity injection molds if all of your components are the same size, shape, material, and look since they can provide easy mold design, manufacturing, and maintenance. Family injection molds are a good choice if your components differ in terms of their sizes, weights, compositions, or aesthetics since they permit part design and variation flexibility.

c. Evaluating Cost Factors

For the third phase, an evaluation of the project’s cost variable is needed, this includes the original investment, ongoing cost, and return on investment. For large-scale manufacturing with high production volume, multi-cavity injection molds can be cost-effective. Similarly, for small-scale manufacturing with modest production volume family injection molds can be cost-effective. This can be achieved by lower tooling costs.

7. Conclusion

In this article, two types of injection molds that are commonly used in industry: multi-cavity injection molds and family injection molds are explored. Working principles, advantages and disadvantages, cost-effectiveness, and applications of those molds for injection molding have been compared and contrasted. A few case studies on the production usage of these mold types in the industry are also included. Additionally, some recommendations for selecting one of those injection molding for injection molding is provided. Choosing the right type of mold is considered important because it affects the quality, cost, and efficiency of the product. If the wrong type of mold is chosen, it can end up with defective parts, wasted material, increased expense, and reduced productivity. Therefore, it’s important to evaluate the production needs, design complexity, and cost factors before molds. By choosing the right type of mold, the injection molding process can be optimized and can achieve the best outcomes and return on investment.

I. Introduction

Plastic injection molding is the most commonly used process in manufacturing. In this process, molten plastic is injected into a heated mold. After cooling and solidification, the plastic material takes the shape of the mold and the finished part is then ejected. Depending on the particular requirements of the product, it may undertake further procedures like trimming, assembly, painting, etc. Different plastic products and components for automotive, electrical components, consumer goods, medical equipment, aerospace parts, etc. can be produced with this process. Different types of plastic materials are used in plastic injection molding based on their material properties. One of the commonly used materials for plastic injection molding is Polyphenylene Oxide (PPO). Polyphenylene Oxide (PPO) is a crystalline thermoplastic. It is widely used for plastic injection molding due to its properties like high-temperature resistance, excellent electrical insulation, resistance to different chemicals, dimensional stability, flame retardancy, versatile application, easy and smooth processing, etc.

II. PPO Plastic

a. Chemical composition and structure

Structurally, PPO comprises phenylene rings linked together by ether linkages in the 1,4 or para-positions, with methyl groups attached to carbon atoms in the 2 and 6 positions. It is produced by oxidative coupling of phenylene oxide monomer using oxygen and copper-based catalysts. It is resistant to high temperatures with a very high glass transition temperature of 210°C. However, due to the difficulty in processing, and poor organic solvent resistance, it is rarely used in its pure form. Therefore, it is commonly used in combination with polystyrene, high-impact styrene-butadiene copolymer, or polyamide to improve melt processability.

Fig 1: Chemical structure of PPO (Source: https://pslc.ws/macrog/ppo.html)

Fig 2: Mechanism of PPO formation (Source: https://pslc.ws/macrog/ppo.html)

The chemical formula of PPO: (C8H8O)n

b. Properties of Modified Polyphenylene Oxide (PPO)

Chemical Resistance	Electrical Properties	Physical properties
Acids-concentrated: Fair	Dielectric constant @1MHz: 2.7	Density (g.cm-3): 1.06
Acids-dilute: Good	Dielectric strength (Kv.mm-1): 16-20	Flammability: HB
Alcohols: Fair	Dissipation factor @ 1kHz: 0.004	Limiting oxygen index (%): 20
Alkalis: Good	Surface resistivity (Ohm/sq): 2×1016	Resistance to Ultra-violet: Good
Aromatic hydrocarbons: Poor	Volume resistivity (Ohm.cm): 1017	Water absorption- over 24 hours (%): 0.1-0.5
Greases and oils: Fair
Halogens: Poor

Mechanical properties

Abrasion resistance (mg/1000 cycles)	Coefficient of friction	Elongation at break (%)	Hardness-Rockwell	Izod impact strength (J m-1)	Poisson’s ratio	Tensile strength (MPa)
20	0.35	50	M78/R115	200	0.38	55-65

Thermal properties

Coefficient of thermal expansion (×10-6 K-1)	Heat-deflection temperature -0.45 MPa (°C)	Heat deflection temperature -1.8 MPa (°C)	Lower working temperature (°C)	Thermal conductivity (W.m-1.K-1) @ 23°C	Upper working temperature (°C)
60	137	125	-40	0.22	80-120

c. Comparison of modified PPO plastic with other plastics

Materials	Tensile strength 73°F (psi)	Flexural Modulus of Elasticity 73°F (psi)	Izod impact (notched) 73°F (Ft-lbs/in of notch)	Heat deflection temperature 0°F (66psi/264psi)	Water absorption Immersion 24 hours (%)
Nyrol® (modified PPO)	9,600	370,000	3.5	279/254	0.07
High Impact Polystyrene	3,500	310,000	2.8	- / 196	-
Polypropylene (PP)	5,400	225,000	1.2	210 / -	Slight
Polycarbonate (PC)	9,500	345,000	12.0-16.0	280/270	0.15
Acrylonitrile Butadiene Styrene (ABS)	4,100	304,000	7.7	200/177	0.30
Polyamide (PA)	12,400	410,000	1.2	-/194	1.20

Fig 3: Plastic material comparison chart (Source: https://precisionpunch.com/plastic-materials-index/)

d. Specific Features and Benefits of PPO and Its Use in Plastic Injection Molding

• High-temperature resistance: PPO can withstand a wide range of high temperatures making it suitable for heat and thermal stress environments.
• Electric insulation: It has high dielectric strength and low dissipation factor for broad temperature and frequency ranges, making it used in electrical and electronic components.
• Chemical resistance: PPO provides chemical resistance to acids, bases, and solvents, and has excellent hydrolytic stability.
• Dimensional stability: PPO offers high dimensional stability with low moisture absorption and minimal shrinkage during molding.
• Flame retardancy: It resists flame propagation and can be used to enhance fire-retardancy in other plastics.
• Cost-effectiveness: PPO demonstrates cost-effectiveness by reducing manufacturing and labor costs and can be combined with other materials to meet specific application requirements without increasing cost.

III. Common Applications of PPO Plastic Injection Molding

• Automotive industry: PPO is used in components like air intake manifolds, engine covers, thermostat housings, dashboard panels, airbag covers, fuel system components, HVAC components, fluid handling components, and battery housings.
• Electrical and electronics: Applications include connectors, sockets, switch housings, circuit breakers, terminal blocks, fuse holders, electrical enclosures, and wire management components.
• Consumer goods: Used in camera bodies, TV and audio equipment, drills, saws, kitchenware, cookware handles, luggage, travel accessories, sporting goods, and office equipment.
• Medical industry: Applied in housing and enclosures for medical devices, surgical instruments, respiratory equipment, dental equipment, patient monitoring devices, laboratory equipment, drug delivery devices, and bioprocessing equipment.

IV. The Injection Molding Process with PPO

1. Material preparation: PPO must be appropriately dried to eliminate moisture before using PPO resin in injection molding. A baking oven can be utilized for 3 hours dry to PPO plastics, and by heating PPO plastic to 750C- 950C.
2. Heating and Melting: All the barrels in the system are carried heat treated to respective corresponding temperature ranges of 2000C to 2600C. The hot flow path adapted to the injection system is heated to 2300C to 2600C. Likewise, the cover half in the injection mold is heated to 650C – 750C, whereas, the dynamic model is heated to 450C – 550C The PPO resin is then loaded into the hopper, where it is subjected to controlled heating with a heated barrel. The resin is converted into molten condition within the temperature range of 2300C to 2700C.
3. Injection: When the molten PPO resin reaches the desirable temperature, it is pushed forward to the injection nozzle located at the end of the barrel. The injection pressure is 100kg/cm2- 120kg/cm2, therefore the molten PPO resin is under high pressure. Then the high-pressure molten PPO is injected into the mold cavity through the nozzle. When PPO fills the cavity, it takes the shape of the part to be produced.
4. Cooling: The mold is equipped with a cooling apparatus that cools and solidifies the PPO material. The timing of cooling forming is 38s.
5. Ejection: After cooling and solidification, the mold is opened and the part is ejected with the help of the ejection mechanism.

Fig 4: Plastic Injection Molding Mechanism (Source: https://vipol.com.vn/service/plastic- injection-molding/)

V. Potential Challenges and Solutions Associated with PPO Plastic Injection Molding

• Hygroscopic nature: PPO is hygroscopic and, therefore can lead to the problems like voids, bubbles, and surface defects. For this reason, proper drying of PPO resin should be prioritized.
• High melt temperature: PPO requires high melt temperature that can lead to increased energy consumption and equipment wear. Therefore, regular inspection of the equipment and maintenance of processing parameters like barrel temperature should be emphasized. Selection of the materials or coatings that can withstand wear and tear should be focused
• Improper mold temperature:Improper mold temperature can cause warping. Control systems should be regularly monitored to maintain precise temperature control.
• Cost: PPO can be comparatively more expensive than other thermoplastics. That’s why the cost-effectiveness of the performance advantage of PPO should be evaluated.
• Environmental impact: PPO plastic can cause negative impacts on the environment because of its non-biodegradable nature. So, environmentally friendly measures and alternatives should be explored.

VI. Best Practices for PPO Plastic Injection Molding

1. Material selection and sourcing: Based on the specific requirements of the product to be produced, the appropriate grade of PPO should be selected. PPO resins and flame-retardant PPO formulations should be collected from reputable suppliers that meet regulatory and performance requirements.
2. Mold Design and Considerations:
   • Ensure proper venting and gating.
   • Implement effective mold temperature control systems.
   • Improve part and mold design to reduce the risk of failure.
   • Experienced mold designers with adequate knowledge of PPO’s characteristics and processing requirements should be engaged in mold design
3. Quality control and Testing:Standard process parameters like injection pressure, temperature, and cooling time based on materials requirements should be developed and optimized. Material testing should be done to verify PPO resin’s quality and consistency. Regular dimensional checks, visual inspection, and testing of performance criteria of finished products should be applied. Proper documentation and recording of process parameters should be emphasized for quality assurance.

VII. Case Studies

Case Study 1: Permian Plastics Medical Device Case Study

The Permian Plastics has been serving Noryl GTX PPO/Nylon resin (a high-performance blend of polyamide and polyphenylene oxide). It possesses unique properties like high heat resistance, flame resistance, clarity, long wear, and the ability to withstand harsh environments. The resin is injection moldable, and the final product was a component of emergency warning lights. Likewise, it can also be utilized in automotive lighting and automotive painted body panels.

Fig 5: NORYL GTX PPO/Nylon (Source: https://shorturl.at/dgwHN)

Lesson learned: Careful selection of the material properties based on the product requirements and with diverse applications is crucial. Quality control measures should be established to ensure product reliability. It is always beneficial to collaborate with quality material suppliers for product development.

Case Study 2: Modified PPO Development and Injection Molding Process for Lightweight Stack Enclosure of Hydrogen Fuel-Cell Electric Vehicles (FCEV)

The study emphasizes two factors: (i) development of modified PPO (mPPO) as an alternative material to aluminum, and (ii) optimization of the injection molding process for stack enclosure production. The key findings of the study demonstrated that mPPO was successful at replacing aluminum by reducing the weight of the stack enclosure while maintaining the required properties. Similarly, the study suggested replacing aluminum with mPPO and optimizing the injection molding process. It not only reduced the weight but also the material costs. Moreover, optimization of the injection molding process, on the other hand, improves productivity by reducing cycle times.

Lesson learned: Material development is crucial to achieving light-weighting goals in the automotive industry. Proper material testing and evaluation should be emphasized to assess the performance requirements of newly developed materials.

VIII. Future Trends in PPO Plastic Injection Molding

Future innovations in PPO materials and molding techniques are more likely to concentrate on environmental sustainability and eco-friendliness. The development of bio-based PPO blends with both improved properties and good recyclability can be considered. Similarly, the reduction of PPO waste production and energy consumption can be achieved with the implementation of a closed-loop recycling system. On the other hand, the application of advanced molding techniques like micro-molding, multi-material molding, and 3D printing to produce different complex PPO components is expected. Additionally, the forecast done by Research and Markets states that the polyphenylene oxide (PPO) market was valued at US$1,298.26 million in 2017 and is expected to reach US$1,879.84 million by 2026 with a growth rate of 4.3% during the forecast period. This indicates a significant increase in the value of the market.

IX. Conclusion

To conclude, PPO offers several exceptional qualities like high-temperature resistance, high dielectric strength, chemical resistance, flame retardancy, and dimensional stability. These properties enhance the versatility of PPO, diversifying its application in different industries. Likewise, several problems associated with pure PPO use have been addressed with the development of modified PPO. Moreover, further innovations have been emphasized in PPO materials and molding techniques to improve performance and sustainability. Therefore, PPO injection molding can be a viable choice for the next plastic design and manufacture-related project.

I. Introduction

Efficient and cost-effective methods of manufacturing have always been a challenge for product developers. The two well-known manufacturing techniques that are most favored are prototype tooling and injection molding. Each of these approaches carries unique strengths and limitations. This article delves into the deep comparison between these two methods based on cost, time efficiency, material selection, complexity, design freedom, as well as quality to understand their differences thoroughly.

II. What is Prototype Tooling?

Prototype tooling (also called rapid tooling) is an approach to manufacturing that allows making tools rapidly as well as cost-effectively in a short period of time. The tooling uses low-cost injection molds to make small batches of products. It is a type of injection mold tooling that is created rapidly at a cost-effective rate so that the complete analysis of the function, validation, and evaluation of your design can be done thoroughly before any mass production. Rapid prototyping tools speed up and make it less expensive to create new products.

Fig 1: Aluminium mold for prototyping (Source: https://www.protolabs.com/services/injection-molding/prototyping/)

III. Classification

1. Soft Tooling:

Soft tooling is a cost-effective option ranging from low to medium-volume production whose flexibility allows for rapid design iterations, accommodates various materials, suits complex geometries, and also offers a smooth finish. It has limited material compatibility and longer cycle times. It lacks durability and wears out quickly. It is further divided into:

• Direct soft tooling
• Indirect soft tooling

Fig 2: Soft tooling molds (Source: https://www.3erp.com/blog/soft-vs-hard-tooling-for-injection-molding/)

2. Hard Tooling:

Hard tooling is produced from durable materials like steel and is perfect for high-volume production that requires precision and durability while providing superior dimensional accuracy, material compatibility, and consistent quality. Its cost is more than soft tooling comparatively. Likewise, hard tooling is further divided into:

• Direct hard tooling
• Indirect hard tooling

Fig 3: Hard tooling mold

Fig 4: Classification of prototype tooling

Advantages of Prototype Tooling:

• Short tooling lead time: Tooling time is shorter than other types of tooling methods.
• Low Cost: Tooling cost is below 5 percent of other conventional kinds of tooling cost.
• Higher tool life: Tool life is significantly higher than others.
• High acceptance: It has a higher acceptance ratio than any other conventional tooling.
• Evaluation and validation: Prototype tooling allows functional testing and validation for the design before heading to mass production which helps in finding failure at early stages.
• Direct Transfer of CAD data: Imperfections that may occur due to misinterpretation of drawings can be avoided using a direct CAD model.

Disadvantages:

• Prototype tooling is less durable and robust.
• Creating multiple molds in this method may result in some dimensional errors.

IV. What is Injection Molding?

Injection molding is used in the manufacture of many popular plastic products such as bottle tops, syringes, remote control covers, and so on. This process involves placing the molten material in the mold where it cools and forms a solid final product. Injection molding is known for its efficiency, accuracy, and ability to produce parts of precise sizes for a wide variety of products commonly used in our daily lives. In addition, it is also used for large-scale applications such as car body parts. In particular, injection molding is used where thousands or millions of uniform parts must be molded.

Fig 5: Injection Molding (Source: https://waykenrm.com/blogs/what-is-injection-molding/)

Classification

• Cube molding
• Die casting
• Gas-assisted injection molding
• Liquid silicone rubber injection molding
• Metal injection molding
• Micro injection molding
• Reaction injection molding
• Thin-wall injection molding

Advantages of Injection Molding:

• High efficiency and speed: It is a highly efficient process with the capacity of producing numerous quantities of parts rapidly.
• Cost-effective in larger productions: Initial costs for setups are relatively high compared to the prototype tooling but the production cost decreases significantly with increments in production quantities. This makes injection molding economically an ideal choice where mass production is required.
• Precise and tight tolerances: It offers tight tolerances in final parts with exceptional precision.
• Flexibility with materials: Injection molding can be used with a variety of materials such as thermoplastics, thermosetting plastics, and elastomers.
• Complex Geometry: Parts with complex geometries can be produced that would be difficult to manufacture using any other manufacturing techniques.
• Minimum wastage: It generates final parts with exceptional precision leading to minimal wastage of excess material. Even wasted material can be reused.
• Consistency and repeatability: Injection molding provides consistent as well as reproducible parts that are almost identical to each other.

Disadvantages:

• This method has high start-up cost.
• It requires longer initial lead times.
• Design changes in this method are expensive.

V. Cost Analysis

Cost factors for prototype tooling

The factors that affect the total cost of prototype tooling are:

• Design complexity: The cost of prototyping becomes high with more complex designs. Therefore, design complexities become crucial factors for the cost of tooling. It is much less for simple geometries and very high for complex designs.
• Size: Larger prototypes use more materials for prototyping and are therefore more expensive.
• Materials: The type of material used for prototyping significantly impacts the cost. Using high-quality materials like steel or aluminum may be more expensive than using plastic.

Cost factors for injection molding

The cost of injection molding depends on several factors, including:

• Order volume: Order volume is the most crucial factor for injection molding production. The cost per production is very low if the order volume is very high.
• Part complexity: Complex parts require more time and effort to manufacture and are therefore more expensive.
• Materials used: The type of material used for injection molding can significantly impact the cost.
• Equipment cost: The cost of equipment for injection molding can vary greatly. This is a one-time investment cost. Professional industrial injection molding equipment costs between $50,000 and $200,000.
• Labor costs: Most of the processes in injection molding are fully automated. However, costs like setup costs, repair costs, and operator costs come into play, resulting in an increment in overall cost.

Comparative cost analysis

When comparing the cost-effectiveness between prototype tooling and injection molding, prototype tooling becomes more cost-effective for small production runs and rapid prototyping due to its lower initial setup costs and no extra labor costs. However, prototype tooling cost increases with design complexity and part size increase. In contrast, injection molding shines in mass production scenarios with lower per-unit production costs for larger order volumes. Although initial setup costs are high and extra labor costs come into play, the total cost per unit is very low compared to a single prototyped unit. Therefore, injection molding is a superior choice if the order volume is high.

Fig 6: Comparison of rough tooling and unit price between prototype tooling and injection molding (Source: https://dankemold.com)

VI. Time Efficiency

Lead time for prototype tooling

The strategy for rapid tooling is to make a less durable tool that is engineered for a much shorter life than a conventional tool. This allows toolmakers to work with less expensive materials and faster manufacturing processes, reducing waste. This is why rapid tooling has a shorter production cycle because of the faster manufacturing speed.

Lead time for injection molding

Injection molding is known for its longer lead times, typically taking 5-7 weeks to manufacture tooling and an additional 2-4 weeks to produce and ship parts. This longer time is because the molds need careful design and testing, which can take several months. Any changes in design further add to the turnaround time.

Comparative time analysis

Prototype tooling is used for shorter life spans with less expensive materials and faster processes. This results in a shorter production cycle. In contrast, injection molding needs mold design and testing, which leads to longer lead times, taking several months from tooling to final parts. Any design changes further extend the process.

VII. Material Selection and Flexibility

Materials commonly used in prototype tooling

Prototype tooling also offers compatibility with many plastics. However, it's crucial to note that abrasive materials such as glass-filled nylon can cause mold wear, which shortens the tool's life. Careful consideration is essential when working with such materials.

• Aluminum Al 7075;
• Carbon steel C45, C50;
• Semi harden Steel P20;
• High polishing steel NAK 80;

Materials commonly used in injection molding

• Semi-harden steel 718, 2083, 8407, H13, etc.;
• Heat treatment is needed;
• High polishing steel NAK 80, S136;

Flexibility in material choice for each method

In prototype tooling, the method aims to finish production with the shortest lead time such that the part produced functions as intended. Tool life isn’t a crucial factor here, so the mold can be made using a wide range of plastics and soft metals. However, in injection molding, the mold has to withstand multiple production cycles under high pressure and temperature, making tool life a crucial factor. Therefore, injection molds are made from semi-hardened steel like 718, 2083, 8407, H13, etc.

VIII. Complexity and Design Freedom

How prototype tooling handles complex designs

Rapid tooling provides greater design flexibility and the ability to quickly incorporate design changes. Utilizing 3D printing and other cutting-edge rapid prototyping techniques allows for the effortless creation of intricate details, customized features, and complex geometries.

How injection molding handles complex designs

Injection molding can handle complex designs once the production mold is set up. However, creating or modifying an injection mold can be a time-consuming and costly process, which may limit design changes during the production phase.

Comparison in terms of design constraints

Flexible and quick design changes have been made possible by 3D printing and rapid prototyping. This allows prototype tooling methods to offer greater freedom in creating intricate, customized, and complex designs. In contrast, injection molding can produce complex designs, but the time and cost associated with mold setup and modifications can restrict design changes during production.

IX. Quality and Precision

Quality considerations in prototype tooling

Prototype tooling creates prototypes that are slightly less precise compared to other tooling methods. Its main purpose is to create a product that functions as intended rapidly and cost-effectively. Prototype tooling often uses materials that may not be as durable and resistant to chemicals and wear. As a result, the prototypes may exhibit minor variations and surface imperfections, making quality, surface finishes, and textures less critical.

Quality considerations in injection molding

Injection molding is known for its exceptional precision and consistency. It excels in producing parts with minimal variation, ensuring tight tolerances and uniformity. Injection molding's ability to maintain consistent dimensions and high-quality finishes is crucial for applications where product quality and precision are paramount, such as medical devices or automotive components.

Comparative quality analysis

Injection molding stands out over prototype tooling in precision and consistency, producing parts with minimal variation and superior quality. In contrast, prototype tooling is designed for rapid and cost-effective prototyping, where some sacrifices are made in precision and surface quality. Injection molding is the better choice if a quality finish is a priority despite lead time and cost.

X. Scalability

Scalability options in prototype tooling

Prototype tooling is limited in terms of scalability. It is excellent for small-batch production and rapid prototyping. However, it may not be the most efficient choice for scaling up to mass production due to the need for new molds and tooling adjustments.

Scalability options in injection molding

Injection molding is highly scalable once the production mold is in place. It can accommodate large production runs with minimal per-unit production costs.

Which is better for scaling up production?

Injection molding is better suited for scaling up production due to its high scalability. It accommodates large production runs efficiently and cost-effectively, while prototype tooling may not be as efficient for mass production due to the need for new molds and adjustments.

XI. Case Studies

Case Study: Prototype Tooling in Artificial Photosynthesis Technology

Innovation and product development often demand rapid tooling and flexible solutions. One of the real-world examples of this is the utilization of prototype tooling in the development of artificial photosynthesis technology as demonstrated by researchers at the University of California, Berkeley, and the Joint Center for Artificial Photosynthesis (JCAP).

The challenge they faced was to fabricate optical components swiftly for use in an artificial photosynthesis prototype. Traditional optical fabrication methods were very time-consuming and impractical for prototyping. Also, their need was for rapid design-to-part cycles and the capacity for quick design modifications.

The team explored three different mold fabrication methods: CNC machining of plastic, CNC machining of aluminum, and 3D printing of plastic. Each method offered its own advantages and challenges. Notably, 3D printing was the most promising result as it allowed for rapid tooling production and could serve as "bridge tooling" while waiting for a hardened steel mold to be designed.

Fig 7: 7PP and COC injection molded parts

These efforts demonstrate the potential of prototype tooling in accelerating the development of innovative technologies such as artificial photosynthesis. Researchers were finally able to iterate and refine their designs easily by embracing the flexibility and speed of 3D printing for prototype tooling. Ultimately, it pushed the boundaries of what's achievable in the field of renewable energy and sustainable technology. This case study highlights the pivotal role that prototype tooling plays in propelling groundbreaking innovations to reality.

Fig 8: 7PP and COC injection molded parts

As printed, 3D printed parts have inadequate surface finish for molding optical components. Three finishing processes were explored: (1) hot-pressing with a steel shaft, (2) coating with printer resin, and (3) mechanically polishing with a scraper and buffer.

Case Study: Injection Molding Revolutionizing the Optical Industry

Injection molding of optical components has seen significant advancements in recent years, enabling its use in various real-world applications. One such example is in the production of high-quality camera lenses for smartphones. Manufacturers have used injection molding to produce complex lens designs efficiently and cost-effectively as consumer demand for better camera performance has increased. This technology allows for the mass production of precise aspheric lens elements.

Another real-world application is in the automotive industry where injection molding is used to produce high-volume optical components such as headlamp lenses. These lenses must meet strict quality and safety standards, making precision molding essential for ensuring optimal light dispersion and visibility.

Additionally, the use of injection-molded optical components has expanded into the medical field. Companies are producing diagnostic devices and medical imaging equipment with molded optical elements that offer excellent performance while keeping production costs down.

Therefore, we can conclude that injection molding of optics has found widespread use in various industries from smartphones and automotive lighting to medical devices, demonstrating its versatility and cost-effectiveness in manufacturing high-volume optical components.

Fig 9: Plastic Aspherical lens made by injection molding (Source: https://sinoptix.eu/portfolio-item/pmma-injected-aspherical-lens/)

Lessons Learned and Best Practices

Prototype tooling and injection molding each have their own advantages in product development. In the first case study, we learned that prototype tooling using soft mold tools allowed designers to iterate their designs rapidly and cost-effectively, though they had to compromise the quality of the mold. In contrast, the second study showed us the importance of injection molding in manufacturing at a large scale. Injection molding successfully produced a large number of lenses for various industries with precision and high quality.

XII. Conclusion

Prototype tooling excels in rapid design iterations and cost-effective prototyping for small batches with a wide range of material choices. However, it sacrifices some durability and precision. Injection molding stands out in mass production with consistent quality, tight tolerances, and scalability, although it demands higher initial costs and longer lead times.

You should choose prototype tooling for rapid prototyping, small-batch production, and quick design changes. Injection molding should be the preferred choice when scalability, precision, and consistent quality are essential in large productions.

We suggest carefully considering your project's scale, budget, and quality requirements when deciding between prototype tooling and injection molding to ensure the most suitable manufacturing approach for your product development needs.

1. Introduction

Injection molding is an old, effective, and one of the leading processes involved in manufacturing the complex product. It enables the mass production of complex shapes with high efficiency and optimum costs. It’s a widely implemented technique of the manufacturing process, and integral to the production of products in our daily life. The injection molding enables production of the large numbers of parts with greater accuracy and in a short time from the multi-cavity tools. It involves the process of heating the polymer materials and then injecting the melted molten materials into the mold under high pressure. The injection molding is a process with high repetitions, which means that all the products produced will be identical i.e., convenient for the consistent production and in large volume. This fast and intensive process involves high pressure and heat for the injection of the molten materials. It uses popular materials like thermoplastics (ABS, PS, PE, PC, PP or TPU). It is a complex process with many variables which impact the overall expenditure of the project. Factors like the complexity of the mold design, type of material used, volume produced, and geographic conditions make the injection molding complex. The businesses of the competitive market of today’s era need efficient and consistent cost implementation in their market, which shows that knowledge of injection molding is paramount. This article focuses on the wide world of injection molding costs, providing a detailed breakdown that enables businesses to make the right decision and optimize their production processes.

Figure 1: Schematic diagram of the typical injection molding machine.

2. Fixed Costs in Injection Molding

Fixed costs of injection molding involve various components that are consistent and do not change with the production level over a period. There are multiple cost drivers for injection molding, out of which the fixed costs are the one that influences the other cost as well. Moreover, the overall financial feasibility of the injection molding is determined by the fixed costs.

Machinery Costs

Fundamentally, machinery cost plays a significant role in fixed expenses. Injection molding requires specialized machinery equipment, which involves considerable initial investment. The cost required for the purchase and maintenance of the injection molding machine must be considered in the fixed cost. The complexity and capabilities of the machines significantly make the machine's price different in the market. The machine required for a certain firm should carefully consider its production requirements and budget capacity to select the most suitable machines to mitigate long-term costs. The machine for injection molding ranges from smaller desktop injection molding machines suitable for the in-house business to large industrial injection molding machines that are utilized by large manufacturers. The production of low volumes of parts by injection molding is most effective with desktop injection molding machines and its cost varies around $350-$500. The large production requires large industrial injection machines which cost anywhere from $50,000-$200,000. These large machines require skilled labor, maintenance, and monitoring.

Facility Costs

Secondly, facility costs are another component of the fixed costs in injection molding. Facility costs generally refer to the expenses associated with the utilities, infrastructure, rental facilities, and space required for the injection molding facility to be operated. The facility costs are driven by the size and location of the injection molding area. Although the size and location differ for different firms it will be a fixed cost for each firm. There are some mostly considerable facility costs which are rent, utilities i.e., electricity, water, etc., suitable environment conditions, timely maintenance and repairs, security, property taxes, and many more. These all-facility costs differ for different places.

Labor Costs

Next, the labor cost is also the part of the fixed cost. But, most of the part of injection molding relies on automation. The process involved in injection molding i.e., CNC machining is operated by Computer Numerical Controlled software, while 3D printing is operated by its software, and also relies on characteristics of the CAD design to produce the mold, EDM machine also runs automatically and further the injection molding also possess automated process. So, the labor costs involved in injection molding are listed below:

• Setup Costs: The setup labor cost comprises all the time taken by the labor to configure the equipment to manufacture the mold and finalized product. For example, while making the molds, some setup of tooling is required which involves the operator’s time.
• Repair Costs: As injection molding is the mechanical process consisting the various mechanical and electrical equipment, it involves repair and maintenance which requires labor.
• Monitoring Costs: Although all the processes involved in injection molding are automized, there are equipment operators who are focused on monitoring the injection molding processes to ensure quality and inventory control.

While producing the product in-house, these all costs are calculated into labor costs. The wage cost for the labor varies with location but will remain the part of fixed cost for the injection molding industry. Furthermore, the method of cost estimation for the labor costs in injection molding is simplified below:

• Determining the number of operators required for the company.
• Calculating the labor working hours.
• Determining the labor rate per hour.
• Calculating the total labor costs.

Licensing and Compliance Costs

Lastly, the licensing and compliance costs are crucial for injection molding. Injection companies must address the requirements of the concerned authorities and claim the license and all the required permits to operate the injection molding industry legally. The licensing and compliance come under the fixed costs considering the costs of business license, quality standard compliances, environmental permits, insurance, legal and consulting fees, taxes, occupational safety and health administration compliances, registration of the company, etc. Moreover, the consent to establish and consent to operate requires all the mentioned documents which fees are fixed for the injection molding industry.

3. Variable Costs in Injection Molding

Variable costs in injection molding consist of different essential factors that ultimately impact the overall cost of production. The factors mentioned for the variable cost includes all the material cost, energy consumption,

Material Costs

Materials cost is one of the active elements of the variable costs in injection molding. The type and amount of the materials used in the injection molding determine the production cost. The raw material cost is the sum of the cost of storage, the cost of labor used, the loss of interest in capital, etc. There are widely used varieties of plastic used for injection molding whose use depends on the requirements of the final parts, including ABS, PS, PE, PC, PP, or TPU. The cost required for the purchase of the materials for the molds depends on the material chosen. For example, if we use high-grade plastic resin, it will increase the material cost but will result in a quality product. The material cost is determined by the model’s design, the material for molding chosen, and the amount of materials required for the injection molding process.

Energy Consumption

Energy consumption by the injection molding process is also one of the crucial element variable costs. It is the amount of energy required to convert the raw materials into the product, which requires a sufficient amount of energy to heat the molds and inject the material. The energy consumption differs with different factors and cost also varies with the change in energy consumption. Energy consumption management is a key element in managing the efficient cost of injection molding. As an example, applying the optimized heating systems and automatically switching off the heating in idle conditions will reduce energy consumption further the cost will be reduced. Furthermore, different elements will help to estimate the cost of the energy consumption in injection molding i.e., machine size and efficiency, total running time, energy tariff, etc. The cost of energy for injection molding varies with different machine sizes. A larger injection molding machine will consume more energy and the production costs will be higher for larger machines.

The energy consumption cost of the injection molding can be calculated using the following relation:

Energy cost=Total Energy Consumption (kWh)×Energy Rate ($/kWh)

The energy consumption data are gathered from all the appliances used in injection molding and then multiplied with the energy rate to calculate the energy cost.

Maintenance cost

Maintenance cost is another key element in the variable costs of injection molding. The equipment of the injection molding requires monitoring and timely maintenance for the efficient running of the machine. Regular maintenance, cleaning, lubrication of the parts, monitoring of the system, and replacement of the parts are the main components to bear the maintenance cost. The timely maintenance will help to reduce the maintenance cost and reduce the overall cost. However, lack of maintenance will lead the machine to breakdown and costly downtime and also lead to production delays

Overhead costs consist of various indirect expenses that do not deal with the production part which include labor, rent, depreciation cost, insurance, and general and administrative costs but that are still part of the injection molding process. For the support in the operation of injection molding, a company may have to allocate a portion of its office space and administrative staff salaries, and these overhead costs contribute to the overall variable cost of injection molding.

4. The Cost of Mold Design and Tooling

The complexity and material of mold are the driving factors in the cost of injection molding. The creation of the mold and development of the product through injection molding is a complex process. Different factors cause the complexity in injection molding like material selection, mold design, mold fabrication, tooling maintenance, part design, environment, and many more. The certain complexities that arise in the mold are listed below:

• Part size and geometry
• Cavity design
• Mold size
• Texture and surface finish
• Tolerance and precision
• Part volume and cavities

Figure 2: Pictorial representation of the complex mold design.

Similarly, there are different materials for the mold. The selection of the right mold material will play a crucial part in the completion of successful injection molding material. Factors like heat resistance, wear resistance, corrosion resistance, cost, and thermal conductivity of the mold material play important roles in the selection of the right mold materials for injection molding. The materials used for injection molds include the following:

• Tool steel: Steel like P20, H13, and S136 are the tool steels used for molds in injection molding. These tool steels are generally used for applications ranging from small to large volumes.
• Stainless steel: The steel grades 420 and 440C are used as mold materials when there is concern about corrosion resistance. They are known for their good polishing properties and can result in a smooth surface finish.
• Aluminum: Aluminum molds are often used for low-volume production and rapid prototyping. The properties of aluminum, like good thermal conductivity and faster cooling, are beneficial, but the low durability and shorter lifespan limit its use to rapid prototyping.

The material commonly used for injection molding is thermoplastic materials due to their unique features, as listed below with their features and costs:

Materials	Features	Applications	Cost (per kg)
Acrylonitrile Butadiene Styrene (ABS)	durable, lightweight	keyboards, phone hardware, LEGO bricks, drainpipe systems, kitchen appliances	$1-$3
Polyethylene (PE)	flexible, impact-resistant, leech-resistant, moisture-resistant, recyclable	food packaging, milk jugs, toys	$4.5-$8.5
Polypropylene (PP)	leech-resistant, flexible	Tupperware, kiddie pools, toys, utensils, car batteries	$1.20-$1.30
Polystyrene (PS)	warp, shrink, and impact resistant	compact disc cases, packaging applications, household appliances	$0.78-$2.98
Nylon/ (POM)	heat-resistant, durable	high-wear parts, quick-release buckles, gears, hand cranks	$2.50-$4.00
Acrylic	Optical clarity, chemical resistant	tinted tubes, lab equipment, medical products, sports equipment, industrial components	$2.00-$2.50
Polycarbonate	impact resistant, optical clarity, vulnerable to chemicals	automobile headlights, bulletproof glass, eyeglasses, greenhouses, DVDs, mobile phones	$1.5-$2.80
Thermoplastic Polyurethane (TPU)	elasticity, transparency, resistances, tensile and tear strength	mobile phones, keyboard protectors, footwear	$1.08-$3.01
Thermoplastic Rubber (TPR)	chemical and weather resistance, high-impact strength	wires and cable insulation, home appliances, fluid dispensers, flexible hoses, catheters	$2.00-$4.00

Next, the mold design is crucial in determining how the final product looks, and a design fee is a must for the mold designer. For a successful molding project, a good mold design is essential. Developing a good mold design requires skilled and experienced manpower. The expertise and experience of the mold designer will determine the effectiveness and efficiency of the mold. Skilled manpower with the ability to optimize the design cost has a higher rate in the market. Depending on the size and complexity, design fees range from $100-$300 and sometimes higher. The roughly estimated hourly rate for the mold designer can be $30-$40. The price is reasonable as they could finish 10-12 simple injection molds in a working day, around 12 hours.

Figure 3: Pictorial representation of the complex mold design.

Next, the manufacture of the mold is a crucial part of injection molding. This part involves the actual construction of the mold of the desired shape, with the involvement of precise machining and assembly. The mold cost depends on the size, complexity, and material selected for the molds. High volume and more complex structures of molds require more time and expertise, thus raising the cost as well.

A mold looks like the negative of a photograph, which transfers the designed geometry and texture of the surface onto the injection-molded part. The manufacture of the injection mold requires a significant startup cost. A straightforward design, suitable for small-scale production amounts ranging from 1000 to 10,000 units, costs nearly $2000 to $5000. Similarly, large-scale molds typically capable of producing 100,000 units or above require a cost of around $100,000 or more.

In recent times, 3D printing materials have enabled the manufacturing of molds for low-run injection molding, i.e., for 100 parts or less. The invention of 3D printing has made the production of small quantities more economically viable than in the past.

Figure 4: Pictorial representation of the complex mold design.

The simplest type of mold manufactured is a straight-pull mold, consisting of two halves: the cavity (front part) and the core (back part). These types of molds are most chosen in the market due to their design ease and cost-effectiveness. Despite these advantages, straight-pull molds have certain limitations, such as the part must have 2-dimensional geometry on both sides.

Figure 5: Pictorial representation of the anatomy of the mold.

Further, for more complex geometries retractable side-action cores or other inserts are required. Side actions core enters the mold either from the top or bottom. The side action core must be used with more concern as it raises the cost rapidly. Injection molded parts consist of two sides i.e., A side facing the cavity and B side facing the core. The A side is responsible for the visual appearance and the surface is usually smooth according to the design specifications whereas the B side is the functional side usually hidden consisting of the structural elements.

Figure 6:Pictorial representation of the straight pull mold.

Figure 7: Pictorial representation of the mold of steel in industry.

Lastly, the mold lifespan has an impact on the overall cost of the injection molding. Mold with a long lifespan may have higher upfront costs but it can save the cost for a long time by reducing the problem of short-term maintenance, and timely replacement of the mold. Different factors could increase the lifespan of every mold i.e., regular maintenance, quality of materials, monitoring, etc.

5. Production Volumes and Economies of Scale

The fundamental decision that the manufacturers of injection molding face is whether to manufacture products in large volume or small volume. The low-volume production of the products for small and medium-sized production businesses which can produce volumes usually up to 10,000 units or less in a month. The high-volume production in injection molding has a production capacity of 100,000 units in a month. Both low-volume and high-volume production have various advantages which are discussed below:

• The advantages of low-volume production are:
• Less expensive tooling.
• It allows one to change the design quickly and have design flexibility.
• It can provide rapid access to the growing markets as it has a short production time.
• The advantages of high-volume production are:
• It can produce the parts in bulk amounts.
• It will reduce the unit costs and the cycle time for the product.
• The production is more often automated.

Every manufacturer of injection molding should make the financial viability of their business strategy. The breakeven point will signify the volume of the production from the injection molding in which the total cost of production is equal to the total revenue. In injection molding, fixed costs like maintenance and overhead costs remain constant despite production volume. The variable cost changes with the number of productions. Thus, the breakeven point serves as the decision-making point for the manufacturer.

Lastly, per-unit cost considerations are important to the economic analysis of injection molding. The low-volume production will lead to a higher per unit cost of the product manufactured from the injection molding while the high-volume production will lead to the reduction in per unit cost of the product. The various data are analyzed to know the cost associated with injection molding and the per unit cost of the product which is presented below in the tabular form:

Production Volume	Low-volume Production	Mid-volume Production	High-volume Production
Production Volume	100	5,000	100,000
Method	In-house mold production and in-house molding	Outsourced mold production and molding	Outsourced mold production and molding
Mold	3D printed polymer	Machined aluminum	Machined steel
Lead time to final parts	1-3 days	2-3 weeks	4-6 weeks
Equipment required	3D printer, desktop injection molding machine
Mold cost	$100	$3,000	$20,000
Labor cost	$2.5/part	$0.5/part	$0.5/part
Total production cost	$400	$13,000	$170,000
Cost per part	$4	$2.6	$1.7

6. Quality and Precision Considerations

In injection molding, quality and precision considerations play a pivotal role. The consideration of both the quality of the product and the precision of the product encompasses different factors in manufacturing by injection molding. The tool design of the injection molding is the crucial part. The product is designed for manufacture in the best possible way the mold tool can make the product quality difference. For high quality, the product costs can exhibit in various forms, such as higher-grade materials, more advanced machinery, and experts. Although these considerations increase the production costs, they meet the customer expectations and ultimately preserve the reputation and market position.

Next, consistent product quality requires regular and intense inspection and quality assurance processes. The inspection and quality assurance costs are linked up with the manpower, equipment, and time of production. For example, an automobile company producing airbags should implement all the strategies and intense inspections to prevent damage to passenger safety. The costs employed with the advanced inspection tools and experts are added to overall production costs in injection molding. Hereby, the detection of defects early in the manufacturing i.e., inspection and quality assurance process will reduce the risk of company downfall and other possible legal liabilities.

Similarly, the error in injection molding when left unchecked, the future result will be vulnerable as it may lead to damage to the company's reputation and prestige. If the faulty product reaches the market and customers experience the poor product, it may tarnish the brand image. The priority on quality and precision in the injection molding process will reduce errors and financial loss for the company as well. Learning from real-world manufacturers can help in making decisions that balance quality and cost-effectiveness.

7. Geographic Considerations

Geographic considerations play a pivotal role in the world of injection molding, impacting everything from production cost to the easiness of the supply chain. Injection molding costs vary across different countries. Countries such as China and Vietnam have lower labor costs than Western countries. Additionally, raw material costs, overhead costs, and energy consumption costs differ from one country to another, which also impacts the overall cost of the injection molding process. Manufacturers should conduct a comprehensive cost analysis to remain competitive in today's market.

Geographic considerations also drive the cost of shipping and logistics in the injection molding process. Key elements for manufacturing companies are markets and suppliers. Longer transportation distances result in increased shipping costs and longer lead times. Ease of supply to the market will automatically lead to a reduction in cost.

In today's world, import/export taxes and tariffs are also significant cost factors for injection molding companies. Taxes between countries and tariffs on imported raw materials or finished products can change the cost structure of the injection molding operation.

8. Strategies to Optimize Costs

In the injection molding process, when precision and efficiency are at the uppermost level, cost optimization is pivotal, greatly impacting the company’s revenue. To achieve optimization, several key strategies are discussed thoroughly in this section.

Material selection is the most notable factor that affects the cost of the product in injection molding. The choice of materials is influential in the overall cost management of the company. High-quality materials may cost more, but they result in a longer mold lifespan and fewer defects, thus reducing overall maintenance and replacement costs. However, selecting cost-effective materials that meet the required functions can reduce costs. The right balance between material quality and cost can help a manufacturer achieve long-term cost savings.

Secondly, designing the molds and parts plays an important role in cost optimization. By adopting design practices that reduce complexity, minimize undercuts, optimize part geometry, and utilize core cavities efficiently, manufacturers can reduce costs as well as the time and resources required by the production cycle. Efficient design can also minimize material waste, directly reducing production costs.

Automation and the utilization of advanced technologies are also integral to the cost optimization strategy for injection molding. Automated systems are advantageous as they operate consistently without halt, leading to high production rates and reduced labor costs. The adoption of advanced technologies in injection molding, such as real-time monitoring, predictive maintenance, robotics, and AI technologies, can minimize unplanned downtime, maintenance costs, rework costs, and more. This adoption of automation and advanced technologies will enhance efficiency and lead to long-term cost savings.

Figure 8: Pictorial representation showing the automated injection molding unit

9. Case Studies

This case study discusses Keysight Plastics Molding Ltd., which uses automation to advance injection molding and expand its business more economically.

Keysight Plastics Molding Ltd., a medium-scale injection molding company, was facing challenges in a highly competitive market with increased production costs. To regain its position in the market, the company decided to optimize its injection molding costs by upgrading its system with automation and advanced technologies.

The company invested in automated robotics systems to optimize production. Robots were installed to handle cyclical tasks such as material removal from parts, quality inspection and assurance before packing, and the packing of products. This reduced human errors and production time, as well as costs. Additionally, the company installed real-time monitoring systems and data analytics tools to analyze material usage, machine performance, and quality control for all produced products. This helped the company polish its products and remain competitive in the market. Furthermore, the automation system helped them identify further optimal paths for cost reduction in injection molding. This optimization method reduced labor costs, other overhead costs, and ensured consistency in product development. This study demonstrates how a traditional molding company utilized optimization strategies to enhance its injection molding business through new technologies.

10. Conclusion

In conclusion, understanding the cost breakdown in injection molding manufacturing companies is essential for competing in today’s market. Several factors drive the cost of injection molding, including fixed costs, variable costs, mold design and tooling costs, production volumes, economies of scale, automation technologies, product quality and consistency, and the geographic positioning of the company. These are the main drivers in determining whether the costs of injection molding fall within the company’s capacity. Therefore, companies should conduct intense cost analysis to identify the exact injection molding costs.

Similarly, this article emphasizes the importance of comprehensive costing for the success of injection molding. This cost analysis will help companies make informed decisions at every stage of production in injection molding, making their businesses more responsive. A deep understanding of costs will help ensure optimal resource utilization, whether in material selection, production volume planning, or mold design.

Finally, the overall cost of injection molding is discussed in this article. It suggests that injection molding companies should utilize strategies to optimize costs, with many examples provided. The article also encourages new business initiators to start the injection molding business with thorough cost analysis and the use of advanced technologies. Additionally, it suggests that injection molding companies remain flexible and adaptable to new markets. The injection molding business is complex, with many cost drivers that must be carefully managed.

Introduction

Personal protective equipment, commonly known as PPE, is equipment that protects the wearer from various hazards. It can be any equipment or clothing that ensures our safety in various industries. Some of the most familiar examples are Gloves, protective ear gear (earplugs, muffs), helmets, hard hats, goggles, respirators, and full-body suits. In this article, we will take a closer look at how plastic injection molding is revolutionizing the production of high-quality PPE. This article also presents an in-depth look at the material selection, design, quality assurance, and market demand and trends of PPE.

Figure 1: PPE (Personal protective equipment) (Source: Slice Products)

The Importance of PPE

PPE plays a very crucial role in the safety of humans in different sectors, where life-threatening accidents can be avoided by just minor injuries. The uses of PPE are widely utilized in industries like healthcare, manufacturing, mining, sports, movie stunts, and so on. For example, in manufacturing industries, PPE protects workers from hazards including chemicals, noise, heat, and flying debris. Overall, the severity of injuries that occur is very low compared to injuries without PPE. Workers are the backbone of any operation, and their safety should be a top priority. In the healthcare industry, PPE equipment like surgical masks and face shields is used to prevent infectious diseases. PPE boosts the confidence of the workers and makes them feel more comfortable while doing work, which leads to increased productivity in the industry. This makes a workplace safe and sound for everyone spreading a positive attitude and motivation to do the best work among workers. So, PPE is just not a set of gears, they are the shield of humans.

Figure 2: Types of PPE and its uses (Source: MnLTAP)

Material Selection for PPE

Material selection is the key factor for effective PPE. The material selection of PPE varies according to their purposes and sectors. For example: a helmet requires high-impact resistance and firefighter gloves require inflammability. In addition, the selection of the material for PPE heavily depends upon the material properties. Plastics are the most common material that is used in the production of PPE. Plastics are durable, lightweight, flexible, and chemical resistant. This makes them an ideal and cost-effective choice for the manufacturing of PPE. Furthermore, Plastics can also be molded into any desirable shapes and sizes to fit the specific needs of the user. However, all plastics are not suitable for the PPE. Some of the most popular and widely used plastics for PPE are listed below:

• Polyethylene (PE): It is a versatile plastic that is used for helmets, gloves, masks, and other protective clothing. It has properties like high impact strength and tensile strength. It is also a low density material with chemical and moisture resistance properties. Its common use is in the production of helmets, gloves, masks, and other PPE clothing.


Figure 3: Protective helmet made up of Polyethylene (Source: Singer)

• Polypropylene (PP): Polypropylene has high tensile strength and provides good resistance to bacteria and fungi. The common applications of polypropylene are surgical masks and N95 respirator masks.


Figure 4: Respirator mask valve made up of Polypropylene (Source: IndiaMart)

• Polycarbonate (PC): Polycarbonate is a plastic with high impact and thermal stability. It also offers transparency for its application. So, most of the uses are in production of goggles, visor, etc.


Figure 5: PPE goggle and visor shield made up of Polycarbonate (Source: Singer)

• Polyvinyl chloride (PVC): Polyvinyl chloride has high flexibility, durability, and resistance to acids and alkalis, which makes them best option for the production of boots, aprons, etc. In addition, they also provide resistance to acids.


Figure 6: Acid and alkali resistant safety boot made up of PVC (Source: Safer Ltd)

• Polyamide (PA): Polyamide, commonly referred to as nylon, are commonly used as safety vests and jackets. Also, they are used in the manufacturing of bulletproof jackets.
• Acrylonitrile butadiene styrene (ABS): This is a thermoplastic polymer with strong, rigid, and impact-resistant properties. They are heat-resistant and easy to mold and finish. ABS is mostly used for making hard hats, earmuffs, and respirator parts.

Injection Molding Process for PPE

Generally, the first step of injection molding for PPE is the part design using CAD software. Then, the molds are designed with added inlet gate(s) and initial venting, and fabricated with high precision to meet quality standards. The materials are then injected into a mold with high pressure, a process known as injection molding.

Injection molding is one of the most used methods in the production of PPE. The plastic injection molding process for PPE involves heating plastic in pellet or grain form until it has melted. The molten plastic is then injected into a closed two-part mold under high pressure. The mold is cooled, and the molten plastic solidifies to the desired shape. The component is then removed from the mold and sent for additional processing if necessary.

Figure 7: Injection molding for safety helmet (source: IMMSolution)

Injection molding offers many advantages for producing PPE over other manufacturing techniques such as:

• Precision: Injection molding offers the production of complex shape products and intricate details with high accuracy and consistency. Thus, it remains a superior choice for manufacturing methods in terms of precision.
• Efficiency: PPE is produced on a large scale with each product being identical to the other. This efficiency capability makes it a superior choice for manufacturing compared to other techniques in mass production.
• Wide range of materials: Different types of PPE are made of various plastics. Injection molding can work with these various types of plastics to create products with different properties and features.
• Customization possibilities: Injection molding allows for branding and adding personal or safety information in PPE products. This enables the inclusion of product details and identification like badges, logos, cautions, etc.

Injection molding can create high-quality PPE that is superior to any other technology for various industries and applications. Therefore, injection molding is the best technique for manufacturing PPE within a short period of time.

Design and Customization of PPE

The world of personal protective equipment has evolved significantly. Design is a crucial step in the development of personal protective equipment. Design should not only be based on aesthetics but also on functionality and user comfort. PPE should be designed to optimize its performance and usability while minimizing its drawbacks and risks.

Let's explore some of the crucial aspects of design considerations and customization possibilities in PPE manufacturing:

• Ergonomics and comfort: PPE is not just for protection; the wearer should feel comfortable while wearing it. PPE should be designed ergonomically to fit well and allow for free movement.
• Functionality: PPE should serve its intended purpose effectively. For instance, a face shield designed for full facial coverage should also allow for easy breathing and communication.
• Biocompatibility: Ensuring the safety of patients and users is crucial when it comes to PPE. PPE that comes into contact with the human body must be designed with biological safety in mind. Appropriate materials should be selected according to the intended use.
• Maintenance and reusability: PPE should be designed for easy maintenance and repeated use without compromising efficiency.
• Quality standards: Designers must focus on standards set for PPE according to the associated risks. Various governing bodies set PPE standards for different regions, such as OSHA, CE, EN ISO, etc.
• Durability: PPE is often subjected to harsh conditions. It should be able to withstand wear and tear, ensuring a longer lifespan and cost-effectiveness.
• Adaptation to hazards: Different industries face varying hazards. Customized PPE can be designed to offer specialized protection. For example, PPE for construction workers may need to withstand impact, while healthcare workers require protection against biological hazards.
• Branding and identifications: Customization extends beyond fit and comfort. PPE needs to be branded with company logos or identification marks, simplifying tracking and management within organizations.
• Sizing: Traditionally, PPE was designed for the average male body. As the workforce has become more diverse, protective equipment must be designed for various sizes of people, including different age groups, races, sexes, etc.
• Fit and filtration: Poorly designed and ill-fitting PPE reduces the safety provided to the wearer. For example, an N95 respirator mask should cover both the mouth and nose properly and fit the wearer. It should also filter contaminated particles and protect the wearer.

The design and customization of PPE are pivotal in ensuring both safety and user comfort. With injection molding technology, we can achieve tailored solutions that address the unique needs of diverse industries and users. Designing and customizing PPE can improve its effectiveness and user satisfaction. However, designing and customizing PPE also requires adherence to quality standards and regulations.

Figure 8: PPE gear set for sports (source: Priority Designs)

Quality Assurance and Standards Compliance

In the previous section, we discussed that design must be based on the quality standards and regulations maintained by governing bodies like OSHA, CE, ISO, etc. There are many other methods that manufacturers must follow in the production of PPE. Here is an overview of the key quality control measures and standards applicable to PPE:

• Regulatory Agencies: Various regulatory agencies set guidelines and standards for PPE. These agencies and standards differ from region to region, such as OSHA (USA), CE (Europe), HSE (UK), etc.
• Material Standards: Materials must be selected according to their mechanical properties like tensile strength, impact resistance, flexural strength, durability, chemical resistance, etc. For example, helmets should be made of FRP (fiber-reinforced plastic) meeting standards such as IS 2925 or EN 397. Safety goggles should be made of polycarbonate material and meet standards like ANSI Z87.1 2003 or EN166.
• Product Testing and Validation: PPE products must undergo various tests to ensure they meet safety and performance standards. Tests may include impact resistance, penetration resistance, flame resistance, chemical resistance, and more. These tests ensure that PPE is reliable enough for use in hazardous environments.
• Certification: PPE manufacturers often seek third-party certification for their products to verify compliance with relevant standards. Some certification bodies include UL (Underwriters Laboratories), NIOSH (National Institute for Occupational Safety and Health), and TÜV (Technischer Überwachungsverein) in Germany.
• Product Labeling: PPE must be properly labeled with all necessary information for the wearer. Most PPE manufacturers use color codes for their products according to the associated risk and application.

Figure 9: Color labeling of helmets for various applications

Quality assurance and standards compliance ensure that PPE products are reliable and trustworthy for users. It enhances the reputation of PPE manufacturers and suppliers. It is important to choose manufacturers who follow the quality control measures and adhere to all standards for the equipment when selecting a PPE supplier for your business.

Market Demand and Trends in PPE Manufacturing

The demand for high-quality Personal Protective Equipment (PPE) has hiked since the COVID-19 pandemic and growing awareness of workplace safety. The market shows that there has always been demand for PPE across various industries including healthcare, construction, manufacturing, and more. This heightened demand doesn’t only reflect the COVID-19 pandemic situation but also the awareness of the organization of their worker safety. The need for PPE has always been there and will continue to exist. The COVID-19 pandemic just exposed the importance of PPE among users. The PPE industry will continue to grow with advancements in technologies.

The market for PPE has significantly increased since the COVID-19 impact. North America is the highest consumer. The global market for personal protective equipment (PPE) was valued at $80.38 billion in 2022 and is projected to grow at a CAGR of 4.7% during the forecast period. It is forecasted to reach $121.51 billion by 2031.

Read More at: Fortune Business Insights

Trends and Innovations:

• Technological Advancements: PPE manufacturers are using innovative materials and smart technologies to add comfort and enhance the protection of PPE.
• Sustainability: Eco-friendly PPE options are gaining attraction. This promotes the global sustainability goal while offering biodegradable or reusable PPE solutions.
• Customization: PPE that fits various sizes of humans is on the rise due to diverse sizes and workforces from industry to industry.

Challenges and Opportunities:

• Supply Chain System: The major challenge for every PPE manufacturer is difficulties in sourcing and delivering PPE. Another issue includes uncertainty of raw materials availability. The shortage of PPE during the COVID-19 pandemic due to disrupted supply chains highlighted the need for a reliable supply chain system.
• Meeting Standards: One of the major challenges is meeting the evolving safety and quality standards. Companies that can match these standards while maintaining the same level of quality PPE will have a greater impact in the market.
• Proper Training and Education on Correct Usage: Providing proper training and education on the correct usage of PPE can be challenging. Companies should focus on creating tutorials or training programs to extend their product’s awareness.

The PPE manufacturing industry has transformed drastically due to awareness and demand for safety. Innovations in technologies and materials have had a remarkable effect on the growth of PPE usage across various industries. Companies that adapt to these changes while addressing the challenges and opportunities will play a major role in safeguarding workplaces worldwide.

Conclusion

Plastic injection molding is the go-to method for creating high-quality PPE. However, careful considerations like material selection, design, quality control, and standards are crucial for manufacturing effective and efficient PPE. The PPE market will continue to grow with increasing demand and awareness of workplace safety. Therefore, the need for high-quality PPE will persist with advancements in technologies, customization, and reliable supply chain systems. Lastly, PPE is not just a product. It is a lifeline for people working in hazardous and risky environments. It is our moral responsibility to equip them with high-quality and precise injection-molded PPE.

Introduction

Innovation begins with the problem and the needs of society. The plastic product development team identifies those problems and their solutions. They list down the features needed and design the product that solves the identified problem. The design involves the features and the concept of the overall product in virtual. Their mission requires the right tooling partner who can convert their idea into reality. These tooling partners play a main role in the development of the plastic products that we use in our daily lives. This article excavates the importance of choosing the best tooling partner for your plastic product development business. It also involves key considerations and strategies to shortlist and choose the partner appropriate for your project. It also explores the symbiotic relationship between product development and plastic tooling.

Figure 1: Partnership between product development and plastic tooling

Conceptualizing Product Development

For any product development, the first need is the vision of a product that solves the identified problem. The innovation begins with this vision which we term as “conceptualization” or simply as “concept”. Conceptualization is the base of product development that illustrates the product’s purpose, functionality, and design. This is the step that saves you a lot of money and time later by defining the product's technical specifications and functional requirements at the initial stage of product development.

Figure 2: Conceptual drawing of the product (source: Schedio Scientific)

It is essential to understand the problem that your product aims to solve as well as the demand and preferences of the potential users in the initial stages of product development. Basically, it also includes research, market surveys, target audiences, design specifications, and product limitations. You should have an overview of your product virtually by means of any CAD software or technical drawing by the end of this phase.

Figure 3: Idea and concept phase

Your product must answer these questions above before finding the tooling partner for your project. Your concept idea must be working and meet the demands with a cost-effective solution. Your idea must be profitable and should be manufacturable. It is very important to have a clear concept and design specifications. This design information needs to be recorded in a document. The next step is to identify a potential partner with plastic tooling expertise who can transform your document’s information into a beautiful product.

Identifying Potential Plastic Tooling Partners

The key part of selecting partners for plastics tooling lies in identifying those who will transform your design into a real product. They are the ones responsible for your product’s overall quality and finish. Research for shortlisting potential partners is mandatory before selecting the right one for your product. Careful consideration and research at this stage are very important for choosing the tooling partner. You might filter the wrong partners and miss the appropriate partners if you misconduct the research. Here are the strategies and considerations to help you with shortlisting potential tooling partners for your business:

Figure 4: Strategies to shortlist right tooling partner

The right tooling partner will definitely have expertise and capabilities that meet your project needs. It is important to choose the partner according to their compatibility with your project for the best outcome. The partner’s location also plays a crucial role. You will definitely need to prefer the partner with the closest location. You need to choose a partner with advanced precision manufacturing technology if your project requires high-quality parts. If you require parts in huge numbers, then you need to seek a manufacturer who has the capability to produce parts in huge numbers. The selection is generally based on your project scope and requirements.

Assessing Technical Proficiency and Expertise

It is essential to look at their technical capabilities and expertise such that you know what they bring to the table while selecting the tooling partner. They are the people that either make or break your project. It is very important to understand their technical competence and knowledge. You should have background information in terms of their ability to provide accurate solutions. Priority should be high for the tooling partner who has a team of engineers with skills and experience of years. Here are some criteria to evaluate the technical skills and expertise of tooling partners:

Figure 5: Criteria to evaluate technical skills, knowledge, and experience

It is also important to understand their ability to handle some specific requirements. You may need to use special material or composite for particular parts. You may also need to make some changes and adjust the design at the last moment which may form complex geometries. You need a partner who can handle these specific requirements and challenges without crossing the deadline and the budget.

Evaluating Design Support and Prototyping Abilities

Your tooling partner should suggest a better option to refine your product’s functionality and manufacturability. Their design support and prototyping abilities impact your overall project. Your partner should have substantial knowledge of design for manufacturing and prototyping and can suggest optimizations to your design for better results. Your partner should also be able to save your time and resources with cost-effective solutions.

Figure 6: Design support by tooling partner

Quality Control and Standards Adherence

Quality and adherence to industry standards are the two things that are non-negotiable for any product development. The evaluation of the potential partner’s ability to maintain industry standards with high-quality parts and their quality assurance processes is a must-do. Quality control is the process to ensure that your product meets the required standards. Inquiry about their quality control processes must be done while choosing the right partner for your business. It is also necessary to know how they inspect and test the molds or the tools they create. A reputable tooling partner will focus on maintaining the standards for the product such that there are no legal issues. These evaluations will give you a brief overview of how your product will meet your expectations and the industry standards.

Analyzing Collaboration and Communication

Collaboration and communication with your tooling partner are essential for the success of your product development journey. Imagine your partner doesn’t listen to your feedback and requests on specific needs. Imagine that they don’t provide any updates about the ongoing process with your product and also exceed your expected budget. The result will be terrible with many misunderstandings and disappointments. So, effective collaboration and communication are the keys to ensure that you and your tooling partner are aligned with similar vision, goals, and timelines.

Figure 7: Effective collaboration and communication

Clear and consistent communication must be done for the development of any product. It is crucial that the tooling partner provides you with regular updates showing the ongoing process and addresses any concerns that may arise. The issue can be mutually solved with effective communication between product development and the partner by allocating more resources or time. Your partner should not be just an expert but also open-minded to hear your feedback and concerns. They also must be ready to adapt and adjust to changing requirements. The collaboration and communication are a two-way thing. The product development team also must consider what the tooling partner has to say. This creates a healthy environment of relationship that leads to effective collaboration and communication ultimately leading to successful completion of the project.

Reviewing Portfolio and Client Testimonials

A good tooling partner must have a solid portfolio of similar projects and a proven history with previous clients. This gives you an oversight of the quality of their work and the feedback from other clients regarding their delivered projects. It is essential to review your potential partner’s portfolio and client feedback to understand their capability and reliability. This evaluation helps you track their record of project completions with other clients and build trust in your partner.

Figure 8: Portfolio of TDL company on producing automobile parts

A portfolio is a showcase of past work and demonstrates the ability to deliver consistent quality. By reviewing their portfolio, you can assess their capability and working diversity, as well as their ability to meet deadlines and budgets. A partner with experience in similar projects should be prioritized.

Client testimonials provide insights into the partner's ability to meet client expectations and needs. Positive feedback on their website or other platforms can indicate their reliability. Conduct online searches and speak with past clients, if possible, to get a clear understanding of their handling of projects.

Negotiating Terms and Finalizing Partnership

The final step involves negotiating terms and finalizing the partnership after completing the evaluation process and selecting the final candidate. It is crucial to have clear contract terms to ensure mutual understanding and a successful partnership. The contract should clarify both parties' understanding of project goals and deliverables, ensuring commitment to successful completion.

• Discussion of project details
• Discussion on the allocated budget and other resources
• Discussion on milestones with a clear roadmap
• Agreement on quality control processes and industry standards
• Determine ownership of intellectual property rights
• Discuss plans for handling unexpected challenges
• Signing a contract with all agreements

A well-drafted contract is essential and should include agreements on project deadlines, specifications, budget, payment terms, and actions for unexpected challenges. The contract should be carefully made to ensure security in case of disputes between both parties. This step finalizes the partnership with your chosen tooling partner.

Figure 9: Finalizing partnership with contract (source: https://www.freepik.com/free-photo/two-men-shaking-hands_3469428.htm#query=contract&position=10&from_view=search&track=sph)

Conclusion

A plastic tooling partner plays a critical role in transforming your plastic product idea into a tangible product. Their contribution to product development is vital, and choosing the right partner involves a thorough evaluation process. You need to develop a concept with design specifications that address problems and meet customer demands before searching for a tooling partner.

The selection process involves identifying partners who match your product background, assessing their technical proficiency, design support, and manufacturing capabilities. They should use their expertise to enhance your design and deliver the project within budget and on time. Evaluate their ability to produce quality parts, maintain industry standards, and ensure effective collaboration and communication.

Reviewing the partner’s portfolio and client testimonials provides insight into their reliability and quality of work. Once you have shortlisted a final partner, finalizing the partnership with a well-drafted contract is essential. This ensures mutual agreement and a successful partnership that can lead to innovation and societal transformation.