In thermoplastic overmolding, a substrate, typically made of a rigid thermoplastic, is first produced using a standard injection molding in a stand-alone injection mold. This first shot component is then hand or robot loaded into a second injection mold where a second thermoplastic material, often softer or with different properties, is injected over or around the first part.

This technique allows for the integration of multiple materials into a single component, enhancing functionality and aesthetics. Common applications include grips, seals, and ergonomic features, where a softer material provides comfort and improved handling.

Overmolding not only reduces assembly time and costs but also enhances product performance by creating a strong bond between materials, minimising the risk of delamination. It is widely used in various industries, including automotive, consumer goods, and medical devices, making it a popular choice for producing high-quality, multifunctional parts.