Overmolding — bonding a second material, usually a softer elastomer, onto a rigid substrate in a second molding step — shows up on orthopedic and surgical instrument handles more than almost any other application. It's a real production process, not a coating, and it comes with its own material and design considerations.

What overmolding actually is

A rigid substrate (commonly a hard plastic or, on some hybrid designs, a metal insert) is molded first, then placed into a second mold cavity where an elastomer — typically a thermoplastic elastomer or silicone — is injected around or over it, forming a chemical or mechanical bond between the two materials.

Where it earns its cost

Soft-touch instrument grips, multi-durometer handles and any component that needs a comfortable, non-slip surface bonded to a rigid structural core are the clearest fit. On surgical instruments specifically, overmolded grips can also serve a functional role — improving control in a gloved, potentially wet grip environment, not just comfort.

Design considerations that affect moldability

Bond strength between the two materials depends on real mechanical or chemical compatibility, not just proximity — some substrate/elastomer combinations bond reliably and others need a mechanical undercut to hold at all. That's a design-for-manufacturing question worth raising early, alongside whether the volume justifies bridge or production tooling for the job.

Overmolding runs alongside standard and bridge injection molding as part of Lab Ready's molding capability. Send the substrate and grip material you're considering and material compatibility is part of the review.