Core Insert molding is used to mold plastic onto metal parts by placing components such as screws or metal pins into tooling before the molding process. The plastic securely holds the metal part after cooling. To prevent issues like dimples from shrinkage, wall and rib thickness must be carefully controlled. For applications requiring thick ribs or walls, gas-assist molding with nitrogen gas injection creates tunnels to eliminate shrinkage. Complex parts may require screw/unscrew structures or specialized core inserts for rotating actions.

The Mold Core Insert forms the interior of the final part and can be located on either plate. For highly complex parts, such as medical injection molding products, loose Mold Core Inserts are used and removed from the mold at the end of each cycle.