Silicone over-molding is a process that is used to cover, bond or encapsulate an existing part with silicone material. For example, a silicone over-molding process may be used for providing a grip surface to a smooth plastic handle, a flexible septum on a hard plastic surface or for encapsulating an electronics assembly for mounting or protection from the environment.
The motivation for over-molding silicone may include a means of final assembly, enhancing physical surface characteristics and feel, providing a self-healing internal access (ie, an integrated septum), creating the finished product enclosure (such as a key-ring LED light), creating a thermally conductive path for heat-sinking or perhaps applying elastic properties to mounting components.
Important things you should know about silicone over-molding:
1. Over-molding bonding strength typically increases over time.
2. Polymers that are ideal for over-molding include: polycarbonate, nylons and other high temperature resins.
3. In order to have a clean silicone over-mold, the over-molded part must be made with the requisite tight tolerance and part samples of exact size are needed. A stable-dimensioned part is needed to develop and maintain the desired clean over-mold outcome.