Gas assist injection molding

In plastic fabrication, Gas-assisted molding has gained significant attention due to its cost-effectiveness. It has now become a developed technology that is widely used in the molding of intricate detail parts to meet exact specifications. Unlike conventional molding techniques, where resins or polymers are used, gas-assisted molding is typically exploited by using pure nitrogen up to 98% purity in an inert form. This injection of gas forces some of the plastic material to leave the finished product with voids in its structure. Additionally, low costs on material, a short turnaround of part formation, and manufacturing lightweight yet string parts are some of its core features.

Keep reading this blog post because this article entails thorough details about gas assist injection molding, its uses, parts made out of this enormous technique, and so much more to know.

Gas Assisted Injection Molding:  A Brief Overview

Gas-assisted injection molding follows the same sequence as conventional molding. Typically, the mold is filled 70 to 80% with molten plastic, which entails the pre-defined shape of intended parts or products. The remaining volume of the mold is filled by pure N2 gas to avoid void formation in molded products. This technique is beneficial for optimally producing parts with tight dimensions and smooth surface finishes. In addition, the risks of warping and distortion are minimal in gas-assisted injection molding techniques.

Common Types of Gas Assist Injection Molding

Usually, product manufacturers employ two types of gas-assisted injection molding techniques: internal and external. Each type has a three-step workflow that is different from the others. the detailed procedure is outlined below.

Internal Gas Assist Molding

Let’s discuss its working mechanism;

  • First, pour the molten plastic into the mold using channels.
  • Then, blow high pressure inert gas, usually nitrogen (98% of purity), to form a bubble in the melted plastic.
  • Lastly, the force exerted by the gas on the plastic forces it to take the shape of the mold in forming the part.

This method is advantageous when designing geometries with thin walls and a relatively low density. The gas’s pressure is constant, preventing the walls from shrinking or distorting, thus ensuring that thin-walled structures are accurately formed. Therefore, this process is best suited for the production of thin-walled parts.

Also, production cycle times are notably shorter than external gas-assisted injection molding. The parts’ thin sections or hollow areas help them cool faster than solid ones.

External Gas Assist Molding

Let’s discuss its principle of working;

  • Unlike other materials, the gas does not get inside the material to form voids or channels.
  • It enters the mold through small channels on one side only while the other is exposed.
  • The gas pressure forces the melted resin to contact the mold walls from the side of the part that is not visible from the aesthetic point of view.

This approach is particularly famous for the high quality of surface finish that can be accomplished.

Moreover, this technique is very efficient in dealing with parts with large surface areas and intricate curved surfaces. The gas channels are arranged in parallel along the entire surface, which makes it easier to apply pressure and fabricate large surface areas with complex shapes.

Gas Type used in the gas-assisted injection molding?

Nitrogen is a widely available inert gas used for molding products. It does not affect plastics and maintains their characteristics and appearance. Pressure is used to spread the material properly and minimize the use of plastic resin.

Materials Used in Gas Assist Injection Molding:

Common material types include;

Acrylonitrile Butadiene Styrene (ABS):

ABS is tough, resilient, and low-density, which makes it ideal for use in various fields. It is widely used in car spare parts, protective casing, and other products. However, in some cases, it can transform, that is, deform.

High-Density Polyethylene (HDPE):

HDPE is selected because of its superior weather ability, chemical ability, and toughness, which is ideal for outdoor use and exposure to various environmental conditions. However, it may possess lower stiffness compared to other materials used to construct various structures.

Polypropylene (PP):

Polypropylene is famous for its chemical inertness. It is also a poor conductor of electricity, has high tensile strength, and has a high melting point, so it is strong and can support heavy loads. However, it loses some of its properties if exposed to direct sunlight, so it is not suitable for use in outdoor conditions.

Polycarbonate (PC):

Polycarbonate is selected for its resistance to impact and is hence suitable for car parts and safety equipment. It is also very durable and does not degrade in strength even under high temperatures. However, polycarbonate is a relatively costly material compared to other engineered-grade thermoplastics.

High Impact Polystyrene (HIPS):

HIPS plays a significant role in meeting impact strengths requirements. It imparts dimensional stability and scaleability in gas assisted injection molded products. Moreover, machining HIPs is typically easy. Comparable to other engineering-grade materials. HIPS has high thermal characteristics and can endure harsh conditions. Mostly, its utility is higher in marine applications.

Pros of Gas Assist Injection Molding:

Gas-assisted injection molding helps replicate parts in precise and accurate dimensions. It also reduces the cycle time of the process and increases production rates and the efficiency of the entire process. Also, gas-assisted molding helps prevent surface defects, which improves the aesthetic look and feel of the parts. Moreover, It minimizes warpage, sink marks, and internal stresses detrimental to part performance, quality, and longevity. The process is economical in the sense that it uses less material, this is because of the hollow sections. More to the point, gas assist molding offers high strength and stiffness and low weight, and therefore a high strength-to-weight ratio.

Cons of Gas Assist Injection Molding:

Although it is beneficial for large-scale production runs, some issues can be encountered in gas-assist molding, particularly when multiple cavities are involved in different sizes for part formation. Thus, problems in one cavity may require the removal of the whole mold while other cavities remain unused, therefore lowering productivity and tending to incur more expense on the project. Also, this molding technique is more elaborate than the others. It requires special equipment and skills to be applied, so it is expensive. Other design constraints may also be attributed to the need to channel and vent the gas, which may limit the design and may have to be manipulated to achieve the best outcome.

What are Some Product Examples Made By Gas Assisted Injection Molding?

Gas-assist injection molding is widely used to create thin-walled symmetrical prototypes and cylindrical sections or voids by applying a high pressure of around 35 MPa to 70 MPa along with an inert gas (typically nitrogen of 98% purity). It is commonly used in many products in different industries. For instance, it produces chair arms, dashboard parts, and seat frames in the furniture and automobile industries. In the household appliance industry, gas-assist molding creates vacuum cleaner bodies and washing machine doors with complex shapes and the required rigidity.

This process is also applied to sports equipment, for instance, handles of tennis rackets and cores of baseball bats. In office and electronics applications, printer frames, monitor stands, and television frames are some of the products that can be produced using this molding technique since it can create intricate designs and minimize the use of material. Also, gas assist injection molding is used in the production of medical equipment such as walker frames and parts of wheelchairs while maintaining the strength and accuracy of the equipment. In the audio industry, speaker housings are produced with improved mechanical strength and appearance due to gas-assisted injection molding.

Gas assist molding

Are Gas Assist Injection Molding Products Strong and Reliable For Longer Term Use?

This process results in the formation of parts that are both light in weight and strong due to the formation of cavities that increase the stiffness of the structure while at the same time reducing the weight. These products are designed to offer good shock absorption and this makes them suitable for use in areas where strength is required.

How long does a product made by gas assist injection molding last?

The life expectancy of gas-assist injection-molded products depends on certain factors, such as the material type used, part design, and intended use—application of the part. If these products are used and maintained properly, they can last many years. The general life and service will vary depending on the application and the product type.

Gas Assist Injection Molding: Is It Expensive?

However, it is crucial to understand that gas assist injection molding is comparatively more costly than the other injection molding processes. The higher costs are due to the need to use special equipment, instruments, and qualified staff to perform the process.

Although there are some drawbacks, such as the machine tool’s higher initial cost than that of a conventional machine tool, the following benefits can be achieved: In addition, the efficiency of gas-assisted injection molding is influenced by factors like the product’s use and the volume of production.

Gas Assist Injection Molding & Reaction Injection Molding: Key Differences

GAIM and RIM are two different processes of molding. GAIM is a process of injecting the plastic material along with high pressure gas to form the voids in the part without polymerization of the thermoplastics. On the other hand, RIM involves the use of liquid intermediates such as isocyanate and polyol that chemically react to form a solid polymer part. Every process needs tools and equipment to perform the operations effectively and efficiently.

Gas Assisted Injection Molding Services at Sincere Tech

Our new services include the ability to provide rapid prototyping services, which enable the creation of physical models of your ideas in a short span of time for further enhancement of the design and faster development of the product.

  • Our expertise is in overmolding, the process of joining two or more substrates or materials to improve performance, appearance, and strength.
  • Our proficiency in insert molding enables us to firmly embed inserts into molded components, enhance assembly and product functionality.
  • In two-shot molding, we can create intricate parts with multiple materials in one process, minimizing assembly and opening up new design opportunities.
  • We also provide extra services such as product assembly, packaging, and logistics to help you manage your supply chain more effectively and efficiently.
  • Choose Sincere Tech Mould as your gas assist injection molding suppliers

and enjoy our extensive services, strict quality and environmental policy, and passion for delivering more than expected to our clients.

  • Let’s collaborate and make your visions become reality.


In this article, Sincere Tech shares valuable insights about gas assisted injection molding by providing a description of its working and industrial application. SincereTech has a broad range of manufacturing solutions for your needs, such as injection molding and other services needed for prototyping and production. Contact us now, and get an engineered free online quote for your plastic fabrication project.


Q1. What equipment is needed for gas assisted injection molding?

Gas-assisted injection molding involves the use of special equipment, such as gas injection units, gas control systems, and molds with channels to accommodate the gas. Another requirement of the injection molding machine is its capability to handle gas injection processes.


Q2. Enlist some issues encountered in gas assisted injection molding.

Some critical issues that may be encountered during the process include gas penetration problems, formation of gas traps, venting, regulation of pressure, and maintaining uniformity of the parts produced within the production cycle.

Q3. What are critical quality control measures in gas assisted injection molding?

Some of the crucial measures that have been adopted in quality control include checking the pressure of the gas, setting the right parameters in the process, maintaining the mold frequently, process checks to avoid parts from defects, and ensuring its design fulfills the exact requirements.

Q4. Can gas-assisted injection molding be used for high-volume production runs?

Yes, gas-assisted injection molding is suitable for both low-volume and high-volume production runs. Still, factors like cycle time, tooling costs, and part complexity may determine its applicability to large-scale production.

Q5. Which Industries employ gas assisted injection molding process?

This process is commonly used in the automotive industry, consumer goods, electronics, medical technology, industrial technology, and sports/recreation articles to produce parts with lightweight, thin-walled, and high mechanical strength.

hdpe injection molding

China Custom Plastic Injection Molding Service – Affordable Custom Parts

Sincere Tech is a well-established custom plastic injection molding company in China that provides high-quality custom tooling and molding solutions. We provide solutions for manufacturing services such as raw material testing, tool manufacturing, molding, surface finishing, and product testing to suit the various needs of customers. Our team of engineers is highly qualified and can ensure the professional execution of orders of any size and complexity.

Our Custom Plastic Injection Molding Services Include:

Custom Rapid Prototype Tooling and Low Volume Injection Molding.

  • Perfect for prototyping or creating a few pieces of the product at a time.
  • They can range from simple machines capable of producing between 50 to 5,000+ parts.

Custom Bridge Tooling and Medium Volume Rapid Injection Molding

  • Ideal for market entry strategies.
  • Manufactures 5000 to 100000+ components.

Custom Production Tooling and High Volume injection Molding.

  • It was created for the mass production of bicycles.
  • Produces 100,000+ parts.

With over a decade of experience in On-demand manufacturing solutions, we have helped many of our customers produce their parts using custom plastic injection molding. We are excited to work with you and bring your products to life accurately and quickly.

custom plastic injection molding China

What is Custom Plastic Injection Molding?

Custom Plastic Injection molding is an efficient process of manufacturing custom plastic parts in any quantity, small, medium, or large. This involves the use of molds where the molten plastic material is poured and allowed to cool and harden to the required shape. This cycle is repeated hundreds or even thousands of times, which enables the production of several custom plastic parts at once. The cost of the custom mold is distributed over the number of parts manufactured, which makes the price per unit only a few $$s or even less. Custom plastic injection molding guarantees uniformity of the parts produced and has more material, color, cosmetic, polish, and surface finishing possibilities than 3D printing or CNC machining.

Sincere Tech is a specialized custom plastic injection molding company that provides prototypes and short-run and volume-run custom molding services. We offer custom plastic parts that meet your exact design requirements while being affordable. Our professional engineering department consults with every injection molding quote offered to customers to facilitate an easy transition from design to production.

Types of Custom Injection Molding Services at Sincere Tech

Sincere Tech is a prestigious custom plastic injection molding services company in China that specializes in providing different types of molding services for low to high-volume production requirements. Here’s a brief overview of the types of injection molding services we provide:

1. Custom Clear Injection Molding

Process: This is a process that involves the use of plastic materials that are transparent to produce parts that need to be precise or semi-clear.

Applications: Suitable for products such as lenses, light covers, and other translucent parts.

Normal material: PC, PMMA, PS, ABS, etc.

2. Custom Insert Molding

Process: Insert molding is a technique in which metal or other parts are placed inside the plastic during injection molding.

Applications: Typically used for manufacturing components with metallic inserts, including threaded bolts, bearings, or electrical contacts.

Normal material:  ABS, PC,PP,PA66, PMMA, PE, PET, PPT, etc

3. Custom Over Molding

Process: Overmolding is a two-shot process in which a second material is molded over an existing part or base material.

Applications: Ideal for manufacturing components made of several materials, for instance, handles with soft grips or cases with seals.

Normal materials: TPE, TPU, ect.

4. Custom Thread Molding

Process: This technique involves the formation of internal or external threads in the molded plastic part without the need for subsequent screw cutting.

Applications: Applicable to parts that require screwing or joining, for instance, caps, closures, and threaded inserts.

Normal material:  ABS, PC,PP,PA66, PMMA, PE, PET, PPS, etc

5. Custom Rubber Molding

Process: Rubber molding entails using elastomers to create flexible, strong parts and components.

Applications: It is recommended for use in gaskets, seals, o-rings, and other components that need to be flexible and have high recoverable elasticity.

Normal material: Rubber.

6. Custom Silicone Rubber Molding

Process: Silicone rubber molding uses silicone to create parts that are thermally stable and able to withstand weathering.

Applications: Applicable for use in medical devices, kitchenware, seals, and gaskets.

Normal material:  Silicone, rubber.

Our technical experts are committed to delivering the best molding services that meet your precise needs. From prototypes to short runs and total production runs, our team of engineers will help make your project successful. Explore China’s best custom injection molding services today, or discuss your injection molding requirements directly with our representative.

China Mould Maker

Customized Injection Molding Costs

The price of customized injection molding is not standard and depends on how you engage our services and your project specifications. Generally, the cost can be broken down into two main components: the total cost of production and the price of the mold or the tools that are used in the production process.

Tooling Cost/Injection Mold Cost/Rapid Tooling Cost

Making the custom mold entails other costs that are not included in the total cost of production. The custom mold cost is paid at the beginning of the injection molding process and depends on the blueprint design of the mold. The time it takes to create a mold depends on the mold’s design and its intricacy. Plastic parts production is initiated only after the mold has been made or finalized. There are two types of manufacturing processes for mold creation: rapid manufacturing and conventional manufacturing, with different prices and production approaches.

If you want to know more about custom mold cost, pleae go to injection molding cost and how much does an injection mold cost page to know more.

Key Factors Influencing Customized Injection Molding Cost

The following steps are involved in customizing injection molding molds.

Design Blueprint and Complexity

The level of preparedness and the level of complexity of the product design is a key factor that influences the costs. The complex designs require more complex molds and take more time to make.

Raw Materials

The cost is determined by the type and quality of the material used on both the plastic products and the mold. In general, it can be stated that the acquisition of higher-grade materials is more costly than that of lower-grade ones.

Manufacturing Technology

The choice between rapid manufacturing and traditional manufacturing technologies is based on cost. Although rapid manufacturing is faster, it is expensive.

Tooling Process

The following are some of the factors that can be associated with the tooling cost: the design of the mold, its features, and the material used to construct it.

Project Requirements

The cost may also be affected by schedules and certain specifications of the project. This may force the client to order rush services which are usually costly.

Additional Processes

Other operations such as branding, pad printing or any other special operations will also add to the price.

The cost of injection molding is determined by the design of the product, the quality of the material used, the technology used in production, and other factors of the project. At Sincere Tech, we offer tailor-made solutions to your needs, whether it is a one-off or a batch run. For more information and to get an online quote for your project, please do not hesitate to contact us.

custom plastic injection molding services

Custom Plastic Injection Molding Method

Custom plastic injection molding entails the use of injection molds, and the quality of the final products depends on the molds and their design. In addition to the molds, technical know-how and experience are crucial in arriving at the structure and design of the injection products and the molds.

Mold-making is one of the core departments in our company, equipped with the most modern tools and employing highly qualified and scientifically oriented staff. This makes it possible for us to have good quality molds and also makes it possible to offer the molds at an affordable possible price and within the shortest time possible.

We also provide technical consulting services for selecting appropriate plastic materials for products. When our customers use large plastic molds for their products, they can benefit from our experience in different engineering plastics. We deal with all types of engineered plastics, including conventional plastics and high-performance thermoplastics, to ensure that we select the right material for the particular application.

Our competencies include all types of large plastic molds and materials, and it has been realized to incorporate high-performance thermoplastics into the large plastic molding.

In addition to the general categories of thermoplastic injection molding services available today, our company provides several particular injection molding services to meet our client’s requirements. These are specific processes designed for specific uses, needs, and problems.

Thermoplastics Materials We Processed

At our In-house set-up, we process the following custom injection molded plastics;

ABS (Acrylonitrile Butadiene Styrene)

ABS is a general-purpose thermoplastic with good impact strength and a high degree of hardness. Its tensile yield strength is 6,500 psi, suitable for many engineering applications that demand strength and durability. Go to ABS injection molding to know more.

Polypropylene (PP)

Polypropylene is a thermoplastic polymer widely used in many applications because of its flexibility and strength. It has a tensile yield strength of 4,900 psi and is used where good chemical resistance and processability are needed. Go to PP injection molding to know more.

Polyoxymethylene (POM):

POM, also known as acetal, is a thermoplastic material with low friction, high stiffness, and good dimensional stability. With a tensile yield strength of 10,000 psi, it is suitable for applications that require high accuracy and mechanical strength of the parts. Go to POM injection molding to know more.


Polycarbonate is a thermoplastic polymer with high heat resistance and impact resistance. It has a tensile yield strength of 9000 psi and is used in applications that demand clarity and strength like eyeglasses and electronics. Go to Polycarbonate injection molding to know more about PC molding.

Polycarbonate/ABS Blend:

This is a combination of polycarbonate and ABS that results in the formation of strong and durable parts. It has a tensile yield strength of 8000 psi and is mainly used in automotive and electronic housing industries. Go to PC/ABS injection molding to know more.

PVC (Polyvinyl Chloride):

PVC is a polymer that has good electrical insulating property, high hardness, and good mechanical property. It has a tensile yield strength of 4,500 psi and this makes it suitable for use in many industries and construction activities.


Nylon is a strong polymer material with high elongation and relatively good wear resistance. It has a tensile yield strength of 8,400 psi and is applied to gears, bearings, and wear-resistant components. Go to Nylon injection molding to know more.

Nylon 30% Glass Fiber:

This nylon composite has enhanced mechanical strength and thermal stability, and the tensile yield strength is 18,000 psi. It is applied in areas where high strength and stiffness of the structure are required. Go to Glass filled Nylon injection molding to know more.

Acrylic (PMMA):

Acrylic is quite popular for its strength, which makes it ideal for use in areas likely to be exposed to pressure. It is commonly used in applications that need to be transparent. It has a tensile yield strength of 9400 psi and is used for lenses, displays, and light guides. Go to PMMA plastic injection molding to check more.


Styrene is another type of plastic that is lightweight and has high impact strength and toughness. It has a tensile yield strength of 6,530 psi and is employed for packaging, disposable cutlery, and modeling.

Polyether Imide (PEI):

PEI is a thermoplastic with high temperature tolerance and good mechanical properties. Its tensile yield strength of 16,000 psi makes it suitable for aerospace, automotive, and medical applications.

custom plastic injection molding

Quality Assurance & Surface Finishing Options For Custom Injection Molded Parts

At Sincere Tech, we know how vital it is to produce high-quality and accurately shaped custom molded parts. When you request an injection molding quote, we provide a variety of quality inspections and finishing options depending on your application’s needs.

  • Designing for Manufacturability Feedback (DFM): Our specialists give detailed comments on your design to make sure that your product is suitable for manufacturing without possible problems, which could slow down the process.
  • Scientific Molding Process Development Report: Our scientific molding reports cover the development process and guarantee that the mold will perform as intended and that the quality of the parts will not deteriorate over time.
  • In-Process CMM Inspection and Machine Monitoring: Our CMM checks and real-time monitoring of the machines ensure that the molding process is accurate and high-quality.
  • First Article Inspection (FAI) and Process Capability Report with GD&T: Our FAI and process capability reports, inclusive of GD&T, assure you that the first set of molded parts meets all the required standards and tolerances.

Wrapping Up

In conclusion, it’s economical and effective to get custom plastic molded parts made in China. China is a preferred destination for manufacturing high-quality plastic components because of its skilled workforce, competitive prices, and advanced manufacturing capabilities. Understanding the factors we have discussed and using the tips for collaboration, you can successfully apply the potential of custom plastic injection molding china industry to introduce new developments and high quality in your production.


Q1. What is Plastic Injection Molding?

Injection molding is a manufacturing process that involves using injection to force molten material into a mold. The plastic cools and hardens into the intended shape; each round is known as a molding cycle or molding shot.

Q2. How Much Does Plastic Injection Molding Cost?

The cost of injection molding varies from $100 to over $ 100,000. The cost factors that are considered include the type of material used, size of the part, quantity ordered, complexity of the part, number of cavities, cycle time, and labor costs.

Q3. How Much Does Injection Molds Cost?

Injection Mold Cost varies depending on the complexity of the mold and the material used in its construction. Injection Mold costs are estimated to be between $1,000 and $100,000+ or even more. The cost of molds is also influenced by the complexity of the mold and its size, where simple and small molds are cheaper than complex and large molds with multiple cavities and features.