Overmolding & Insert Molding

Our rapid overmolding and insert molding processes produce custom prototypes and on-demand production parts in as fast as 15 days. We use aluminum molds that offer cost-efficient tooling, producing parts from a range of thermoplastic and liquid silicone rubber materials.

How Does Overmolding Work?

With overmolding, the production of the substrate parts is a standard injection molding process involving an aluminum mold with no heating or cooling lines running through it. Cycle times are a bit longer, which allows our molders to monitor fill pressure, cosmetic concerns, and the basic quality of the parts. When the total run of substrate parts are molded, overmold tooling is then assembled to the press. The substrate parts are placed by hand into mold where each part is overmolded with either a thermoplastic or liquid silicone rubber material.

How Does Insert Molding Work?

Insert molding is a similar process but instead uses a preformed part—often metal—that is loaded into a mold where it is then overmolded with plastic to create a final component. When the run is complete, parts (or the initial sample run) are boxed and shipped shortly thereafter.


injection molding icon

25 to 5,000+

Shipped in 15 days or less

Molds starting at $4,990


Best For:
  • on-demand production
  • bridge tooling
  • pilot runs
  • rapid prototyping

Overmolding Materials and Inserts

We stock a range of thermoplastic and LSR materials for overmolding that are suitable for various part applications and industries. Customer-supplied metal inserts are also accepted.



Design Guidelines

Our basic guidelines for overmolding and insert molding include important design considerations to help improve part manufacturability, enhance cosmetic appearance, and reduce overall production time.


press operator examines liquid silicone rubber part

Free moldability analysis within hours