Insert molding is a process where a rigid plastic resin is injected over another material, typically metal. The metal piece is placed in a tool for the plastic to be injected around. Encapsulating the insert with plastic creates a single molded piece that’s typically stronger than one created by assembling separate pieces together.

This process is most commonly used for custom-machined metal parts like threaded fasteners and electrical parts. There is no chemical bonding between metal inserts and plastic, so the insert and resin components must be designed for mechanical bonding.

Insert molding is controllable and allows better encapsulation than other methods used to mold plastic around metal parts. Molded inserts eliminate the need for a secondary insert installation process, making it more time-and-cost-efficient.

Benefits of Insert Molding:

Eliminates secondary assembly operations like gluing and fastening.

Creates design functions and features that are not feasible by plastic alone.

The encapsulating process can add strength and durability to parts.