Double shot Injection Molding

2K or Double Injection Molding

Double Shot injection molding, also known as two-shot or dual-shot injection molding, is a highly versatile manufacturing process used to create complex parts with multiple colors, materials, or textures. It involves injecting two different materials into a single mold, enabling the production of innovative and functional products. Special 2K Injection moulding machine is required for this technique.

Process Overview


Mold Preparation

A mold is created with two or more cavities designed to accommodate the different materials. The mold is precision-engineered to ensure proper alignment and sealing.

First Shot

The first material, typically a rigid or structural polymer, is injected into the mold cavity. It partially fills the cavity or specific areas as required. Eg PP, PS, ABS, PC Etc. 

Intermediate Step

The mold is opened, and the partially filled cavity is prepared for the second shot. This may involve cooling or other necessary treatments.

Second Shot

The second material, often a soft or flexible polymer, is injected into the remaining cavity space or specific areas. It bonds with the first material to create the final product. Eg. TPE, PVC, TPU etc.

Cooling and Ejection

The mold is cooled to solidify the materials. Once cooled, the finished part is ejected from the mold.

Material Selection



The materials must be compatible to ensure proper bonding and adhesion between the two shots.


Each material should possess the desired characteristics such as hardness, flexibility, color, or texture.

Processing Parameters

Materials must have similar melt temperatures and flow properties to ensure successful injection and bonding.

Benefits and Application of Double shot Injection Molding

Design Consideration

Cost and Production Efficiency

Application of Double shot Injection Molding



Medical Devices

Consumer Goods

Choosing Between 2K Injection Molding and Overmolding


Material Combination and Complexity

2K Injection Molding: If the design requires multiple materials integrated throughout the entire part, with complex geometries and precise material placement, 2K injection molding is the preferred choice.
Overmolding: If the design requires adding a secondary material layer to specific regions or features of an existing part, overmolding is a suitable option. It provides the flexibility to enhance specific areas with different materials.

Design Flexibility

2K Injection Molding:This technique offers greater design flexibility, allowing for intricate part geometries, multiple colors, and material combinations within a single part.
Overmolding:While overmolding provides design flexibility by adding a layer of a different material, it is more limited in terms of part complexity and color options compared to 2K injection molding.

Production Considerations

Tooling and Equipment: 2K injection molding typically requires specialized equipment and molds capable of sequential injection. Overmolding may involve modifying existing molds or using dedicated overmolding machines
Production Efficiency: 2K injection molding is more suitable for high-volume production due to its efficient sequential injection process. Overmolding can be more time-consuming and may require additional steps for pre-molding the primary part before the overmolding process.

Cost Considerations

2K Injection Molding: This technique generally requires a higher initial investment in specialized equipment and molds. It is suitable for applications that justify the added cost by leveraging the benefits of complex part designs and material combinations.
Overmolding: Overmolding can be a more cost-effective option if only specific regions or features of the part require additional material layers, especially when modifying existing molds.