What Materials Are Used for Injection Molding?

In the world of manufacturing, injection molding is a widely utilized process for creating intricate and precise plastic parts. The materials used in injection molding play a crucial role in determining the final quality, strength, and functionality of the produced components. In this article, we will delve into the various materials commonly used for injection molding and explore their unique characteristics. By understanding the different options available, you can make informed decisions when it comes to selecting the most suitable material for your specific manufacturing needs.
1. Thermoplastics

Thermoplastics are the most commonly used materials in injection molding due to their versatility and wide range of properties. These materials have the ability to soften when heated and solidify upon cooling repeatedly, allowing for easy molding and recycling processes. Some of the popular thermoplastics used in injection molding include:



Polypropylene (PP)

Polypropylene is a lightweight and flexible thermoplastic that offers excellent chemical resistance, low cost, and high impact strength. It is commonly used in the automotive, packaging, and consumer goods industries.



Acrylonitrile Butadiene Styrene (ABS)

ABS is a strong and durable thermoplastic that possesses good impact resistance and dimensional stability. It is often used in the production of electronic enclosures, automotive components, and household appliances.



Polycarbonate (PC)

Polycarbonate is a transparent and highly impact-resistant thermoplastic. It is known for its excellent optical clarity, making it suitable for applications such as safety goggles, lenses, and automotive lighting.



Polyethylene (PE)

Polyethylene is a versatile thermoplastic that comes in various forms, including high-density polyethylene (HDPE) and low-density polyethylene (LDPE). It offers excellent chemical resistance, electrical insulation properties, and is commonly used in packaging and piping systems.
2. Engineering Plastics

Engineering plastics are a class of materials that exhibit enhanced mechanical, thermal, and chemical properties compared to standard thermoplastics. These materials are specifically designed to withstand demanding environments and provide superior performance. Here are some notable examples:







Polyamide (PA)

Polyamide, commonly known as nylon, is a strong and lightweight engineering plastic. It possesses excellent tensile strength, abrasion resistance, and is often utilized in applications such as gears, bearings, and structural components.



Polycarbonate-ABS (PC-ABS)

PC-ABS is a blend of polycarbonate and ABS, combining the toughness and heat resistance of polycarbonate with the processability and cost-effectiveness of ABS. It finds extensive use in automotive, electronics, and telecommunications industries.



Polyether Ether Ketone (PEEK)

PEEK is a high-performance engineering plastic known for its exceptional mechanical, thermal, and chemical resistance properties. It is commonly employed in aerospace, medical, and oil and gas applications where extreme conditions are present.



Polyphenylene Sulfide (PPS)

PPS is a high-temperature engineering plastic that offers excellent chemical resistance and dimensional stability at elevated temperatures. It is often used in electrical and electronic components, as well as automotive parts.
3. Elastomers

Elastomers, also known as rubber-like materials, are characterized by their elasticity and flexibility. They are commonly utilized when parts require excellent sealing, cushioning, or shock-absorbing properties. Let’s explore a few examples:



Thermoplastic Elastomers (TPE)

TPEs are a versatile group of elastomers that combine the processing advantages of thermoplastics with the elasticity and softness of traditional rubber. They find extensive use in the automotive industry, medical devices, and consumer products.



Silicone

Silicone elastomers are known for their high-temperature resistance, low toxicity, and excellent electrical insulation properties. They are widely used in the medical and food industries, as well as for seals, gaskets, and electronic components.
Conclusion

In summary, the materials used for injection molding are diverse and tailored to meet specific requirements in terms of strength, flexibility, chemical resistance, and more. This article provided an overview of various materials, including thermoplastics like polypropylene, ABS, polycarbonate, and polyethylene, as well as engineering plastics such as polyamide, PC-ABS, PEEK, and PPS. Additionally, elastomers like TPEs and silicone were also discussed. By understanding the unique properties of these materials, you can make informed decisions and select the most suitable option for your injection molding needs.



Remember, choosing the right material is crucial in achieving high-quality and cost-effective production. Always consult with experts in the field to ensure the optimal selection of materials for your specific application. WIT MOLD can meet the demand for plastic products that are reasonably priced, durable, and require precise specifications every time. We are your one-stop supplier of high-quality, cost-competitive domestic molded plastic products using various plastic materials.

The Ultimate Guide to Gas Assist Injection Molding

 

 

What is Gas Assist Injection Molding?

Gas assist injection molding (GAIM) is an enhanced injection molding process often applied for complex parts, large parts and parts requiring an attractive, cosmetic finish.

The types of parts benefiting most from this process include:

• large panels
• enclosures
• handles
• doors and bezels
• tube or rod-shaped parts

How Does Gas Assist Work?

The gas assist process is introduced at the finish of the mold filling stage while the resin is still liquid.  Pressurized gas (usually nitrogen) is used in place of pack pressure from the molding machine.  The pressure from the gas completes the filling of the mold cavity, forcing an even distribution of molten resin against the mold. The gas is held inside during the entire cooling phase and then is vented, leaving a hollow void.  For internal gas-assist molding, the void is inside the plastic.  For external gas assist molding, the void is on the outside surface, typically the backside of a part.

Benefits with Gas Assist

The gas-assist process gets results when part design elements make the part difficult to manufacture using straight injection molding.  GAIM allows for more design flexibility while still being able to provide these benefits:

• Thin-walled parts with greater strength and rigidity
• Creation of hollowed out areas, reducing part weight
• Reduction of molded-in stress for improved dimensional stability
• Better surface finish with no sink marks
• Less part shrinkage and reduced warpage

Design Advantages with Gas Assist

1. Complex Designs

For the design engineer, using GAIM expands design options and helps to minimize design changes to make the part manufacturable using injection molding. One of the greatest benefits is the ability to produce complex parts.  Oftentimes with straight injection molding, parts having different wall thicknesses are molded separately and assembled later.

GAIM allows multiple parts to be combined into one, reducing the need for secondary assembly processes – even if the parts have different wall thicknesses.  This is because gas-assist allows heavy wall sections to intersect thinner ones. Support ribs and bosses can achieve tighter tolerances and be designed larger without fear of sink marks. Gas channels are directed toward these areas and the consistent pressure during the cooling phase eliminates sink marks, associated with these support features, on the front side of the part.

2. Metal Replacement

Gas-assist allows the production of thin-walled components that have solid but hollow areas.  The resulting strength and lightweight part can often replace metal fabricated or die cast parts, and reduce product cost.

3. Large parts

The introduction of gas pressure aids in mold filling, providing uniform pressure throughout the part that lasts through the cooling stage. The result is a part with less shrinkage and reduced warpage. Part weight can also be reduced by creating hollowed out areas.

4. Cosmetic finishes

Where an attractive finished surface is required, gas-assist prevents sink areas that eliminate or at least minimize secondary operations to improve part appearance including sanding and priming.

5. Hollow parts

The gas can create hollowed out areas within parts like handles, which decreases part weight and still provides strength.

 

 

Cost Benefits with Gas Assist

1. Extended Tool Life

With gas-assist, lower clamping force is required because lower pressures are used.  This results in less mold wear extending the life of the tool.

2. Less Energy Cost

With lower clamping force required, larger molds can be used in smaller presses.  Smaller presses consume less power and help to decrease the cost of manufacturing the part.

3. Less Machine Time

A more rapid cooling period helps to reduce cycle time which in turn lowers manufacturing expense per part.

4. Lower Material Cost

Less material is used to produce the part because hollow areas inside of the part are created with the gas and with less resin used, the part cost is lowered.

5. Quality Results

With gas-assist injection molding, the process is typically easier to control than conventional injection molding. A dependable, repeatable process provides consistent production results and less waste.

Common pitfalls

There are many common pitfalls when it comes to Gas Assisted Injection Moulding. Firstly, it is more complex and more expensive to set up than ordinary injection molding. if the tooling price of injection mold shocks you, gas-assisted injection molds will blow you away. Also, by introducing gas into the molding mix, this variable must be precisely tracked, managed and controlled. Without experienced machine operators and technicians, the molding process could go disastrously wrong. The control of the gas also contributes to variable wall thicknesses, especially in tight corners and this is something you generally want to avoid.

Gas Assist Tool Design

If you want to achieve high-quality results, make sure you get the tool design right.

Regardless of what injection molding process will be used, it is important to engage your molder during the early stages of part design in the design for manufacturing (DFM) phase. Tooling cost, timeline, and resulting part quality will be directly impacted by the quality and efficacy of the tool.  When determining the optimal way to mold apart, engineers will consider all product requirements including application, resin selection, and cost considerations. Mold flow analysis is used to find design constraints so that adjustments can be made. When the tooling engineer determines gas-assist is the best solution, the tool will be designed with gas channels built into the mold that will allow the addition of nitrogen gas during the molding process. Determining your molding method early will conserve tooling costs and help to maintain project timelines.  Getting your molder involved early will be critical to a cost-effective, high-quality product.

 

To learn more about this process or to receive assistance with your project, contact WIT MOLD.

Advantages And Disadvantages of Two-shot Injection Molding

Two-shot injection molding, also known as 2K molding or double injection molding, is a specialized manufacturing process that allows the production of complex, multi-material or multi-colored plastic parts in a single operation. This innovative technique offers several advantages and has its share of disadvantages. In this article, we will explore the pros and cons of two-shot injection molding to help you understand when and why it is employed in various industries.

Advantages of Two-Shot Injection Molding:

1. Enhanced Design Flexibility:

   Two-shot molding enables the creation of intricate and multi-material designs that would be challenging or impossible to achieve with traditional single-shot injection molding. This flexibility opens up new possibilities in product design.

2. Improved Product Quality:

   By combining different materials or colors in a single part, two-shot molding reduces the need for secondary assembly processes, leading to improved product quality and consistency. There are fewer chances for errors during assembly.

3. Cost Savings:

   Despite the initial setup costs, two-shot molding can be cost-effective in the long run. It eliminates the need for additional processes such as adhesive bonding or mechanical assembly, reducing labor costs and enhancing production efficiency.

4. Enhanced Aesthetics:

   This method allows for the integration of different colors and textures within a single component. This is especially valuable in industries where aesthetics play a critical role, such as consumer electronics or automotive interiors.

5. Reduced Cycle Times:

   Two-shot molding can streamline production processes by eliminating the need to remove parts from molds and assemble them separately. This can result in shorter cycle times and increased productivity.

Disadvantages of Two-Shot Injection Molding:

1. Complex Process:

   Two-shot molding requires specialized machinery and tooling, making it a more complex and expensive process to set up compared to traditional injection molding. Initial investments can be a barrier for some manufacturers.

2. Limited Material Compatibility:

   Not all materials are compatible with two-shot molding. Material selection is crucial, and the materials must have similar melt temperatures to ensure successful bonding. This limitation can restrict material choices.

3. Tooling Maintenance:

   The molds used in two-shot injection molding are more intricate and complex, requiring higher maintenance and potentially longer lead times for repairs or modifications.

4. Design Constraints:

   Designing for two-shot molding can be challenging. Engineers need to consider material compatibility, flow characteristics, and the order of injection, which may impose design constraints.

5. Risk of Defects:

   The potential for defects, such as material bleeding or delamination between the two materials, exists in two-shot molding. Proper process control and quality assurance measures are essential to mitigate these risks.

Conclusion

Two-shot injection molding is a powerful manufacturing technique that offers numerous advantages, such as design flexibility, improved product quality, cost savings, and enhanced aesthetics. However, it also comes with its own set of challenges, including higher initial costs, limited material compatibility, and design constraints. Whether two-shot injection molding is the right choice for a particular application depends on the specific requirements of the project and the trade-offs between its advantages and disadvantages. When used appropriately, it can be a valuable tool for creating complex and high-quality plastic components.

What Are The Requirements For Injection Molding Machines For Precision Injection Molding?

Precision injection molding machine refers to the molding machinery and equipment suitable for the molding production of precision plastic products. For a precision injection molding machine, how should we measure or judge?
Many precision injection molding machines are also required

① High injection pressure and fast injection speed.

② The clamping system has enough rigidity and precision. The so-called precision of closing refers to the uniformity, adjustability, stability and repeatability of the closing force, as well as the high precision of the opening and closing position of the mold.

③ The pressure, flow rate, temperature and measurement can be accurately controlled to the corresponding accuracy, and the multi-stage injection can be used to ensure the reproducibility of the molding process and the repeated accuracy of the product.
Precision injection molding machines can achieve the benefits of high pressure molding

A, improve the precision and quality of precision products.

Injection pressure has the most obvious effect on molding shrinkage. When the injection pressure reaches 392MPa, the shrinkage rate of molding is almost zero. At this time, the accuracy of the product is only affected by the mold control or the environment. Experimental results show that the mechanical strength of the parts can be increased by 3 ~ 33% when the injection pressure is 98 ~ 392MPa.

B, can reduce the wall thickness of precision products, improve the molding length.

Taking PC as an example, the ordinary injection pressure of 177Mpa can form products with wall thickness of 0.8mm, while the precision injection pressure of 392MPa can form products with thickness of 0.45mm or more. Ultrahigh pressure injection machines can obtain products with higher flow ratio.

C. Increasing injection pressure can give full play to the efficacy of injection speed.
Injection molding machine performance to achieve precision injection

Injection molding products have been used in various fields, widely used to replace high-precision metal parts, so as to put forward strict requirements on dimensional accuracy, mass accuracy, apparent mass and mechanical properties of injection parts. At the same time, the technological factors affecting the quality of injection molding products also put forward higher requirements.

The ideal control state of injection molding machine is to directly control product size, mass, apparent mass, mechanical properties and other variables as feedback signals for feedback control. However, the method of direct measurement and conversion of these non-electric quantities into electrical signals has not been solved for the time being, and can only be solved by controlling the controllable variables of the injection molding machine that affect the quality of the above-mentioned products. .

We are a precision injection molding company, if you need please feel free to contact us.

Common Defects Of Injection Molds And Their Solutions

An injection mold is a tool for producing plastic products and for giving them a complete structure and precise dimensions. Read on for more information about common problems and solutions for injection molds.






A mismatch between mold and injection molding machine

Causes:

1. Positioning ring position is not correct, size is too big or too small.

2. Wrong position and size of the ejector hole of the mold; wrong position and size of the forced pull reset hole.

3. Mold width size is too big; mold height size is too small.

Solution:

1. Adjust the ejector hole position and size; adjust the reset hole position and size.

2. Replace the positioning ring; adjust the position and size of the positioning ring.

3. Change the tonnage of a large injection molding machine; increase the thickness of the mold.


Bad quality of parts

Causes:

1. The fit-gap is too large.

2. Poor glue walking, trapped air.

3. Ejector pin is too small, uneven ejection.

4. Too small bevel, burr, hardness is not enough.

5. Uneven injection pressure, insufficient strength of product form.

6. Processing error.

7. Far from the gate, low mold temperature.

Solution:

1. Trim the gate, pressure uniformity, strengthen the product strength.

2. Reasonable adjustment of clearance and grinding work part of the parting surface.

3. Improve the gate, increase the mold temperature.

4. Add local glue, add exhaust.

5. Re-processing.

6. Increase the ejector pin, evenly distributed.

7. Repair burr, increase slope, nitriding.






The parts are difficult to fill and difficult to take

Causes:

1. The pouring system is blocked, the runner cross-section size is too small, the gate arrangement is unreasonable, and the gate size is small.

2. The limit stroke of the mold is not enough, the extraction stroke of the mold is not enough, the ejecting stroke of the mold is not enough.

Solution:

1. Check whether the limit, core extraction, and ejection strokes meet the design requirements and adjust the strokes that do not meet the requirements.

2. Check the runner and gate of each section of the pouring system, and fix the parts concerned.


Mold opening and closing ejecting reset action is not smooth

Causes:

1. Slanting ejector, ejector pin sliding is not smooth.

2. Mold frame guide column, guide sleeve sliding is not smooth, with too tight

3. Reset spring elasticity or pre-pressure is not enough.

Solution:

1. Increase or replace the spring.

2. Repair or replace the guide pillar, guide bush.

3. Check and repair the slanting top, ejector pin.


Mold water transportation is not working or water leakage

Causes:

1. Water sealing rubber ring and water pipe joint are not sealed enough.

2. The mold water channel is blocked and the inlet and outlet water pipe joints are connected in the wrong way.

Solution:

1. Check the cooling system inlet and outlet water pipe joints connection and each section of the waterway, repair the relevant parts.

2. Check the water sealing rubber ring and water pipe joints, repair or replace the parts.



WIT MOLD is a very professional mold design and mold manufacturer located in southern China and has passed the ISO2009:2015 international quality Our injection molding process can be customized according to your unique project. If you are interested, please feel free to contact us.

Pros And Cons Of Thermoset Injection Molding

Weighing the pros and cons of the molding process for your composites can help you determine whether it is the right choice for your project needs. Manufacturing plastic or composite parts requires heating and pouring the raw materials into a mold that has been specially made for the part. The four most common molding processes are:

ㆍCompression

ㆍInjection

ㆍTransfer

ㆍExtrusion

Different molding processes are used to create different works. In this article, we will weigh the pros and cons of the injection molding process for thermoset composites.
Advantages of thermoset injection molding

Injection-molded parts may be the most suitable one for several reasons:

ㆍMany different types of materials can be used for injection molding, including thermoplastics and thermosetting resins, polymers, and elastomers. This provides engineers with a lot of control over which hybrid material will produce the best results, especially when it is necessary to meet specific performance requirements.

ㆍVery suitable for high-volume operation.

ㆍPrecision and low waste. Due to the specific mold and material combination, compared with other processes, there is less waste of injection molded parts.

ㆍShort cooling time-the injection molded parts cool quickly, reducing the time required for the injection molded parts to be released from the mold.





Thermoset Injection Molding
Disadvantages of thermoset injection molding

For the above reasons, injection molding is an excellent process, but it also has certain limitations and defects. These disadvantages include:

ㆍMold costs – these costs can be very important because precision-made molds are required.

ㆍFlash – Flash is inevitable when injection molding thermoset plastics. Once the part is created and ejected from the mold, the next step is to automatically or manually remove the flash (excess material). Due to the high viscosity of liquid plastics, a flash of thermoplastics is not a problem.

ㆍPart size – The size of the part being created is very important in the molding process. Typically, smaller part sizes (0.1 lb to 6 lb) are injection molded, while larger parts are transfer or compression molded. The number of orders will also determine which molding process is best for the project. Compression molding may be used for smaller parts with a low (or high) volume, while transfer molding may be used for medium to high volume projects. Injection molding will be ideal for large-volume running smaller pieces.

Finally, when choosing a molding process for your part, it is always recommended to talk to a thermoset composite or thermoplastic engineer. After assessing your needs, they will be the most capable and able to make suggestions for your work and provide the highest quality products at the most reasonable cost.

We are a thermoset injection molding supplier. Please feel free to contact us if you are interested in our thermoset injection molding or other products.

Advantages And Differences Of Two Shot Injection Molding

There are a variety of manufacturing methods used to manufacture products that use plastic polymers, including two-shot injection molding, compression thermoset molding, and extrusion. Although all of these are viable manufacturing processes, this process has several advantages that make it the first choice of many plastic manufacturers. The process is relatively simple; inject one material into the mold to make the initial part of the product, and then inject a second material that is compatible with the raw material. Many manufacturers use this method to make plastics or polymers for three good reasons.



Two-shot injection molding is cost-effective

The two-step process only requires one machine cycle, the way the initial mold is rotated and the product placed around the second mold, so that a second, compatible thermoplastic can be inserted into the second mold. Because this technology uses only one cycle, rather than a separate machine cycle, any production operation cost is lower, and fewer employees are required to manufacture the finished product while delivering more projects per run. It also ensures a firm bond between the materials without the need for further assembly down the line.



Two-shot injection molding



Strengthen product quality

Two-shot injection molding improves the quality of most thermoplastics in the following aspects:
Improved aesthetics. When products are made of different colored plastics or polymers, they look better and are more attractive to consumers. If more than one color or texture is used, the product will look more expensive.
Improve ergonomics. Because this process allows the use of a soft-touch surface, as a result, items can have ergonomically designed handles or other parts. This is especially important for tools, medical equipment, and other hand-held items.
When silicone plastic and other rubber materials are used for gaskets and other parts that require a strong seal, it provides a better seal.
It allows you to combine the outstanding comfort and practicality of hard and soft polymers with even the smallest products.
Compared with overmolding or a more traditional insertion process, it can greatly reduce the number of dislocations.
It enables manufacturers to create more complex mold designs using multiple materials that cannot be effectively bonded by other processes.
The bond created is very strong, creating products that are more durable, more reliable, and have a longer lifespan.



Versatility

Product manufacturers favor two-shot injection molding, with a wide range of applications, including automotive interior parts, medical equipment, tools, and toys. It allows manufacturers to combine various materials and colors to create final products that are both strong and attractive. Some materials can be effectively combined with this process, including silicone and thermoplastics, nylon and thermoplastic elastomers, or hard nylon and soft-touch materials.
Two-shot injection molding can solve your company’s product production dilemma. An experienced plastic manufacturer can guide you through the process from concept to finished product and ensure a cost-effective solution.
We are Two-shot injection molding suppliers. Please feel free to contact us if you need or want to know about our products.