Rapid Injection Molding China: What You Need to Know

If you need to produce plastic parts quickly and cost-effectively, rapid injection molding is a great solution. This manufacturing process can turn your design into a high-quality part in a matter of days, with low tooling costs and high customization options. And if you're looking for a reliable and competitive supplier of rapid injection molding services, China is definitely worth considering.

In this blog post, we'll explain the key advantages and challenges of rapid injection molding, and specifically how China can meet your needs. We'll also give you some tips on how to choose the right injection molding supplier and optimize your design for this process.

Advantages of Rapid Injection Molding

The basic principle of injection molding is fairly simple: molten plastic material is injected into a mold cavity, where it cools and solidifies into the desired shape. However, the actual implementation of injection molding involves many factors that can affect the quality, cost, and speed of the process. Here are some of the key advantages of rapid injection molding:

Speed: Rapid injection molding typically takes a few days to a few weeks, depending on the complexity of the part and the volume of the production run. This is much faster than traditional injection molding, which can take several weeks to several months.

Cost-effectiveness: Rapid injection molding is significantly cheaper than traditional injection molding, especially for small to medium-sized production runs. This is because the tooling costs are much lower, as the molds are usually made of aluminum or other soft materials instead of steel.

Design flexibility: Rapid injection molding allows for a wide range of part geometries and features, such as undercuts, threads, and textures. This means that you can create complex and customized parts without the need for additional machining or assembly steps.

Material variety: Rapid injection molding supports a wide range of plastic materials, including engineering-grade thermoplastics, elastomers, and biopolymers. This gives you the freedom to choose the best material for your application, depending on factors such as strength, temperature resistance, and environmental impact.

Challenges of Rapid Injection Molding

Although rapid injection molding offers many benefits, there are also some challenges that you need to be aware of:

Lower production volume: Rapid injection molding is suitable for production runs of up to a few thousand parts, but it may not be cost-effective for larger volumes. If you need to produce hundreds of thousands of parts per year, you may need to consider other options such as traditional injection molding or other mass production methods.

Limits on part size and complexity: Rapid injection molding has some limitations on the size and complexity of the parts that can be produced. For example, large or thick-walled parts may require longer cooling times or special handling techniques. Similarly, parts with internal or external threads, undercuts, or overhangs may require additional tooling or process steps.

Variation in quality: Rapid injection molding relies on a shorter production cycle and a soft tooling material, which can result in some variation in part quality compared to traditional injection molding. This may affect factors such as dimensional accuracy, surface finish, and material properties. However, most quality issues can be addressed through careful design and process optimization.

Why China for Rapid Injection Molding?

Now that you know the basics of rapid injection molding, you may wonder why you should choose China as your supplier. Here are some reasons why China is a popular destination for rapid injection molding:

Low labor costs: China has a large workforce with relatively low labor costs compared to other countries. This can translate into lower production costs for you, especially for labor-intensive tasks such as mold-making, machine operation, and quality inspection.

High specialization: China has a thriving manufacturing industry that has developed deep expertise in injection molding, particularly for small to medium-sized production runs. This means that you can find many specialized suppliers who can provide high-quality and cost-effective services.

Advanced technology: Although China was once known for low-tech and low-cost manufacturing, it has now become a leader in advanced technologies such as robotics, automation, and 3D printing. This means that Chinese suppliers can offer you a wide range of services and capabilities, from rapid prototyping to custom tooling to precision machining.

Cultural proximity: If you're based in North America, Europe, or Asia-Pacific, China may be a good choice for rapid injection molding because of its cultural proximity and easy access to transportation and communication networks. This can help you streamline your supply chain and reduce your lead times and costs.

Choosing a Rapid Injection Molding Supplier in China

Of course, not all injection molding suppliers in China are created equal. Here are some tips on how to choose the right supplier for your needs:

Look for experience and specialization: Choose a supplier who has a proven track record in rapid injection molding, particularly for your application and material requirements. Ask for references and case studies to verify their expertise and quality standards.

Evaluate their quality systems: Make sure your supplier has robust quality control systems in place, such as ISO 9001 or other relevant certifications. Insist on seeing their inspection reports, process documentation, and traceability records to ensure that your parts meet your specifications and industry standards.

Verify their tooling capabilities: Rapid injection molding relies on soft tooling materials such as aluminum or epoxy. Ask your supplier about their tooling design and maintenance processes, as well as their tooling lifespan and replacement costs. Make sure they can handle your part geometry and volume requirements.

Check their production capacity and lead times: Depending on your part volume and delivery schedule, you may need a supplier who can handle multiple production runs or provide just-in-time delivery. Ask your supplier about their production capacity, lead times, and shipping options to make sure they can meet your expectations.

Communicate clearly and often: Rapid injection molding involves many design and process decisions that can affect the final part quality, cost, and speed. Make sure you communicate your requirements, expectations, and feedback clearly and often with your supplier. Use tools such as CAD and 3D modeling to visualize and validate your design before production.

Optimizing Your Design for Rapid Injection Molding

Finally, here are some tips on how to optimize your part design for rapid injection molding, particularly in China:

Minimize complexity and thickness: Keep your part geometry and wall thickness as simple and uniform as possible, to reduce the risk of warping, sink marks, or other quality issues. Avoid internal undercuts, sharp corners, or complex surface textures that may require additional tooling or processing.

Consider gate placement and size: The gate is the point where the molten plastic enters the mold cavity. Choose a gate location and size that minimizes the flow length and pressure drops, to ensure that the plastic fills the cavity evenly and without defects. A gate size of 0.5-1.0 mm is usually recommended for rapid injection molding.

Use suitable materials and colors: Choose a plastic material that matches your performance requirements, such as PET, PA, PPS, TPE, or PC. Avoid using additives or fillers that may affect the material properties or processing parameters. Similarly, choose a color that is easy to reproduce and does not affect the part quality or function.

Add draft angles: Draft angles are the angles that help the part eject from the mold without damage or sticking. Typically, a draft angle of 1-2 degrees per side is recommended for rapid injection molding. However, make sure that the draft angles do not affect the part geometry or fit.

Keep tolerances in mind: Rapid injection molding can achieve tight tolerances of +/- 0.01-0.05 mm, depending on the part size and complexity. However, too tight tolerances may lead to manufacturing difficulties or quality issues. Consult your supplier to determine the optimal tolerances for your part design.


Rapid injection molding is a powerful tool for producing plastic parts quickly, cheaply, and with high customization. By choosing a reliable and specialized supplier in China, you can leverage the advantages of this process and optimize your design for the best quality and cost. Keep in mind the challenges and tips we've outlined in this blog post, and don't hesitate to contact us if you have any further questions or needs.

rapid injection molding china

On-demand Rapid Injection Molding

Sigma’s rapid tooling service helps you to have the low volume to large volume plastic parts done, with no compromise on the material selection.

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Our rapid injection molding Application

Sigma Technik Limited's rapid injection molding service injects molten plastic materials into molds using injection molding machines and molds, and cools and solidifies them over a certain period of time, ultimately forming the required plastic parts. This manufacturing process is usually suitable for producing small and medium-sized plastic parts, which can obtain high-quality and precise parts in a short period of time.

Plastic Injection Molding

Injection molding is a common manufacturing process to produce low volume to large volumes of parts typically made out of plastic. The process involves injecting molten material into a mold and letting it cool to a solid-state.

Liquid Silicone Rubber Molding

Liquid Silicone Rubber is known as LSR, which is a process used to produce parts made from silicone rubber, widely used create products such as medical devices, automotive parts, baby care products, and many others.

2K Injection molding

2K injection molding is a manufacturing process in which two different types of plastic materials are molded together in a single operation to create a single homogeneous component. This process allows for efficient and cost-effective production of high-quality parts that can perform unique functions.

Overmolding and Insert Molding

Overmolding / Insert molding combines two or more materials into a single part, one of the material is usually soft and flexible, or metal. The purpose of overmolding/insert molding is to add functionality, improve grip, provide protection, or enhance aesthetics.

Mission And Vision

Rapid injection molding materials


ABS is a type of plastic with high strength, hardness, and toughness. It has good impact resistance and wear resistance, and is suitable for manufacturing shells, components, and models.


PC is a transparent, high-strength, high-temperature resistant, and excellent electrical insulation material. It is suitable for manufacturing transparent components, electronic components, and automotive components.


PP is a relatively flexible material with excellent corrosion resistance and high temperature resistance. It is suitable for manufacturing containers, pipelines, baby bottles, etc.


PA is a material with high strength, high rigidity, and wear resistance. It is suitable for manufacturing gears, bearings, brackets, etc.


POM is a material with excellent wear resistance, toughness, and rigidity. It is suitable for manufacturing gears, bearings, pulleys, etc.


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About Us

What can we do?

Sigma Technik Limited, as a prototype production company and rapid manufacturer focusing on rapid prototyping and low volume production of plastic and metal parts, has advanced manufacturing technology, one-stop service, diversified manufacturing methods, on-demand manufacturing services and efficient manufacturing processes, which can provide customers with high-quality, efficient and customized product manufacturing services and help customers improve product quality and market competitiveness.


Rapid Injection Molding Service Application

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Rapid Injection Molding FAQs

Burrs appear on the surface of the product, which affects its aesthetics and safety. The solution can be to adjust the parameters of the injection molding machine, such as temperature, pressure, speed, etc., or to perform post-processing, such as polishing, sandblasting, etc.

The warping deformation of the product is usually caused by unstable parameters such as temperature and pressure of the injection molding machine, or improper mold design. The solution can be to adjust parameters such as temperature and pressure, or to redesign the mold.

The occurrence of bubbles inside the product may be due to the high temperature of the injection molding machine and the high moisture content of the material. The solution can be to reduce the temperature of the injection molding machine, adjust the water content of the material, increase the pressure of the injection molding machine, etc.

The product size deviation is too large, which may be caused by material thermal expansion, mold deformation and other reasons. The solution can be to adjust parameters and optimize mold design based on material characteristics.