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Two Shot Molding

Two shot molding, also called double shot injection molding, dual shot injection molding,multi shot injection molding or 2k injection moulding is one category of injection molding using two different thermoplastic materials to produce injection molded parts in two colors or two components in the two shot injection molding process to produce 2 shot molding in large quantities quickly, economically and efficiently. Multi multi injection molding has characteristics as below:

  • Two shot injection molding, co-injection, two color injection molding and multi component injection molding are all variants of advanced molding techniques.

  • A combination of hard plastics and soft materials.

  • Two-step process is executed in a single press cycle.

  • Combine two or more components to eliminate additional assembly costs.

Keyplast as top of 2 shot injection molding companies, with years of expertise and cutting-edge technology, we offer precise and efficient 2 shot injection molding solutions for a wide range of industries. Our skilled team and state-of-the-art facilities ensure top-notch quality and fast turnaround times. Trust KeyPlast for your complex multi material injection molding needs. Contact us today to discuss your project and experience the excellence of KeyPlast's double shot molding capabilities.

Two Shot Moulding Services

Two Shot Molding Process

Two shot injection molding has two stages in the whole process.

Firstly one shot of materials is injected into a mold and cooled to form a solid part. Secondly, the mold opens and rotates 180 degrees and then closes. The second shot of materials is injected into the mold, through or around the first molded part. After sufficient cooling, the mold opens and the multi-resin molded part is ejected. 2 shot moulding has key factors as below:

  • Melting temperature for the materials

  • Wall temperature for the mold

  • Injection speed for the molded parts

  • Delay time between injections

  • Temperature of the components

Two Shot Injection Molding Design Guide

The mold used in two shot molding consists of different tool sets. In rotating platen settings, these two shot injection molding tools share the same core, but different cavities. The runner must be designed to close during its inactive forming step.

Wall thickness is an important two shot molding design consideration when designing parts for a number of reasons:

Due to the molding pressure from the second step, the substrate wall should be thick enough to withstand the force without collapsing.

Walls should not exceed traditional thickness guidelines to produce effects attributable to irregular cooling.

To ensure accurate and thorough flow of 2k molding material into all parts of the cavity, the wall thickness should not fall below a certain minimum value.

Ideally, materials should be injected in a certain order, taking into account the following factors:

The first shot should be the harder plastic of the two.

If transparent and opaque materials are used, inject transparent materials first.

Generally speaking, the material with higher temperature is injected first.

For mold frame and insert design:

Make sure the mold can be rotated 180 degrees.

Any insertion should be symmetric.

The push rod plate and thimble are stabilized by a return spring to prevent damage during mold rotation.

The cooling system of double shot molding must be able to function adequately on the first and second shots.

Double Shot Moulding Products Gallery

Why choose Keyplast as your two shot molding company?

Keyplast is one of the leading two shot molding companies located in Huangyan, Zhejiang province China, with extensive injection molding experience and a quality and efficient team. Here are some reasons to choose Keyplast for twin-shot moulding.

Advanced technology and capabilities

Keyplast invest in state-of-the-art equipment and technologies to ensure high-quality and precise manufacturing. With our own two-shot molding factory, we have the necessary machinery, such as specialized injection molding machines and tooling, to handle dual-injection moulding efficiently.

Quality control and testing

Keyplast have stringent quality control measures in place to ensure the final product meets your specifications. We perform thorough testing and inspections throughout the manufacturing process to maintain consistency and reliability.


With two-shot molding factory, Keyplast can offer competitive pricing for their two-shot molding services. By optimizing the double-injection molding processs and utilizing efficient techniques,  Keyplast is able to provide cost-effective solutions while maintaining high quality.

Experience and expertise

Keyplast have a proven track record in two-shot moulding, with experience in a wide range of industries and applications. As a professional two-shot molding company, we have a team of skilled engineers and technicians who understand the intricacies of double-shot moulding and can provide expert guidance throughout the double-injection molding process.

Customization and design support

Keyplast offer two-shot molding design and engineering support to help optimize your product for double-injection moulding. We work closely with you to understand your requirements, provide design recommendations, and ensure the manufacturability of your parts.

Dual-Injection Molding FAQs

What are the different types of two-shot injection molding?

Different types of two-shot injection molding primarily vary based on the molding process and arrangement of injection units. Here are the main types:

  • Rotational Two-Shot Injection Molding: This is the most common type. In this two-shot molding process, when the first material is injected into a mold, the mold is then rotated on a horizontal axis to inject the second material. It is widely used to make parts of different colors or different materials.

  • Transfer Injection Molding:In this 2k moulding process, after the first injection of material, the mold is rotated and the cavity side of the mold is filled with a second material. This can be used to make parts that require two different types of plastic materials but have complex designs that cannot be produced in a single mold.

  • Core Back Two-Shot Injection Molding:This 2 shot injection molding process is also known as the reverse core or movable core injection molding. The first material is injected, after which a core inside the mold retracts or moves to create space for the second material to be injected. This is typically used to make parts with overmolding or when the two materials have complex geometries.

  • Sandwich Molding or Co-Injection Molding: In this two-shot injection molding process, two materials are injected into the mold at the same time, with one material (the skin material) wrapping around the other (the core material). This applies to the creation of a part with different internal and external materials.

What are the typical tolerances for injection molded parts?

Tolerances for injection molded parts can vary widely depending on the material being used, the design of the part, the specific process parameters, and the intended application of the final product.As a general rule, typical injection molding tolerances range from ±0.002 inches (0.05mm) to ±0.005 inches (0.13mm) for basic size and up to ±0.015 inches (0.38mm) for contour and location, depending on the size of the part.

What is the minimum order qty?

To cater to diverse needs, we maintain a highly flexible order policy. Our minimum order quantity is as low as one unit, allowing you to order according to your specific requirements and capacity.

How long does it take to make molded parts?

We are fully committed to providing our customers with efficient and high quality injection molding services, and the processing time for our products can vary depending on the complexity of the part. For simpler parts, we can usually produce in a quick turnaround time of 7 to 10 days. Standard parts typically take 20 to 30 days. However, for more complex parts that require additional work and precision, machining times can extend to 50 to 60 days. We appreciate your understanding and assure you that we are committed to maintaining the highest standards of quality and accuracy throughout the process.

How do I know if two-shot injection molding is right for my project?

Dual-injection moulding can be very beneficial if you have parts in multiple materials, colors, or parts that need to be bonded together. It can combine these aspects into a single, multi-component part, freeing you from additional assembly steps. At the same time twin-shot moulding can provide a high degree of quality and precision, allowing for seamless integration of multiple materials. It is cost-effective for larger production runs, reducing the need for secondary operations such as assembly and improving cycle times. However, for small production runs, the high initial setup cost may not be worth it.

Twin Shot Injection Moulding Advantages

Cmpared to other plastic molding methods , the most important bent of 2 shot molding is more economical to manufacture multi-components in the injection molding process as below

Part Consolidation

Dual injection moulding need lower multi-components cost, including the developing, engineering and validation costs related to each additional part and savings in production and assembly.

Improved Efficiency

Improvement of effectiveness and efficiency, allowing one single mold but multi-components to be injected, thus simplifying the abor operations and eliminating secondary operations , such as further needs for welding or connecting multi-components after plastic injection molding process of double injection molding.

Improved Quality

Improvement of quality and function of double shot molding, permitting lower tolerances than other molding processes, requiring high-qualified accuracy and repeatability and reducing the rate of defect parts.

Complex Moldings

Create new mold designs of two shot moulding and allow manufacturing more complex mold designs, Iike multi-metenvels, multi-components or multi-colors that can not be achieved by other molding processes.

Two Shot Injection Molding Applications

Two-shot injection molding, also known as two-component injection molding or double-injection molding, offers a wide range of applications across various industries. Here are some common applications of dual-shot injection moulding:

  • Automotive Industry: Two-shot injection molding is widely used in the automotive industry for manufacturing components such as multi-colored knobs, buttons, handles, and interior trim. Two-shot moulding allows for the integration of different materials with varying hardness, textures, and colors, enhancing the aesthetics and functionality of automotive parts.

  • Electronics and Consumer Goods: Double-injection molding is employed in the production of electronic devices and consumer goods. Dual-shot molding enables the creation of products with soft-touch grips, ergonomic designs, and integrated seals or gaskets. Examples include mobile phone cases, computer keyboards, remote controls, and game controllers.

  • Medical and Healthcare: The medical industry benefits from dual injection moulding for producing devices and components with complex geometries and specialized functions. Double-shot plastic injection molding enables the combination of rigid and flexible materials, facilitating the manufacturing of medical equipment like syringe plungers, drug delivery systems, and surgical instruments.

  • Packaging Industry: Double-shot molding finds applications in the packaging industry to create containers, closures, and caps with customized colors, textures, and sealing features. Two-shot injection moulding enables the integration of rigid and elastomeric materials, ensuring optimal functionality and aesthetic appeal.

  • Aerospace and Defense: Two-shot injection molding is utilized in the aerospace and defense sectors for manufacturing components with high durability, lightweight properties, and improved functionality. Double shot injection molding enables the integration of different materials to create parts such as grips, handles, switches, and seals for various applications within these industries.

  • Household Appliances: Double-shot injection molding is employed in the production of household appliances, offering enhanced aesthetics, ergonomics, and functionality. Double-shot injection molding enables the combination of materials with different properties to create durable and visually appealing components for appliances like kitchen utensils, power tools, and vacuum cleaner parts.

These are just a few examples of the diverse applications of two-shot injection molding. Its versatility and ability to combine different materials in a single molding process make it a valuable technique for creating complex and innovative products across multiple industries.

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Office: NO. 3609 Wuyue Office Building 11, Huangyan, Taizhou, Zhejiang, China, 318020
Factory: No 328, Xiaoliqiao Beiyang Huangyan, Taizhou, Zhejiang, China 318020