Plastic Injection Manufacturing

What types of inserts can be molded into plastic parts?

Common inserts include threaded metal fasteners (brass, stainless steel), metal pins and bushings, electronic connectors, magnets, batteries, springs, and even PCB assemblies. The insert is placed in the mold before injection, and the plastic flows around it, creating a strong mechanical and sometimes chemical bond. At Ichiplas, we design the mold to hold each insert precisely in position during injection.

What is the advantage of insert molding over press-fitting or ultrasonic insertion?

Insert molding creates a stronger bond than post-molding insertion methods because the plastic solidifies directly around the insert, filling undercuts and knurling patterns completely. It also eliminates a secondary assembly step, reducing labour cost and improving consistency. For threaded inserts, insert molding typically provides higher pull-out and torque resistance than press-fit or heat-staked alternatives.

What materials are compatible with insert molding?

Most rigid thermoplastics work well with metal inserts — common combinations include ABS, PC, PC/ABS, Nylon, PBT, and POM with brass, steel, or aluminium inserts. For glass-filled materials (Nylon GF, PBT GF), the abrasive resin requires high-grade mold steel. Our engineering team advises on the best material and insert combination for each application.

Can insert molding be combined with overmolding?

Yes. Complex parts can incorporate both metal inserts and overmolded soft-touch surfaces in a multi-step molding process. For example, a power tool housing might have threaded brass inserts molded into a rigid PC/ABS substrate, which is then overmolded with a TPE grip surface. Ichiplas has extensive experience with these multi-process assemblies.