Two Shot Molding

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

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.

Whether two-shot injection molding is better than overmolding depends on the specific application and requirements of the part you're producing. Here’s a brief comparison to help you decide:

Two-Shot Injection Molding:

• Process: Involves injecting two different materials into a single mold, typically in a sequential manner. The first material is injected and cooled, then the second material is injected over or around the first.

• Advantages:

• Integrated Components: Allows for complex geometries and integration of different materials in a single piece, which can reduce assembly time and cost.

• Enhanced Performance: Combines materials with different properties, such as a rigid core with a soft, flexible outer layer.

• Improved Aesthetics: Can achieve multi-color or multi-material parts with better consistency and alignment.

Overmolding:

• Process: Involves molding a base component first, then applying a second material over it in a subsequent molding step. The two materials bond together through a chemical or mechanical interaction.

• Advantages:

• Flexibility: Useful for adding features like grips or seals to existing parts, or combining hard and soft materials.

• Cost-Effective: Can be less expensive than two-shot molding, especially for low-to-mid volume production.

• Customization: Allows for easy modification of the overmolded component or the addition of different materials in separate steps.

Summary:

• Two-Shot Injection Molding: Best for high-volume production where material properties and aesthetics are crucial, and where integration of different materials in a single mold is beneficial.

• Overmolding: Ideal for adding features or soft materials to existing parts, and can be more cost-effective for lower production volumes or simpler applications.