1.What is the Substrate?
The substrate could really be anything; a machined metal part, a molded plastic part, or even an existing product like threaded inserts, screws, or electrical connectors. It is the first piece in what will eventually become a single continuous part composed of chemically bonded and often mechanically interlocked materials of separate types.
What is the Overmolding Material?
Overmold materials (typically plastic) start off in pellet form. These pellets are mixed with additives like colorants, foaming agents, and other fillers. They’re then heated to their melting point and injected into the mold tooling as a liquid. There are some limitations on what materials are suitable for overmolding. If you are overmolding a metal part with plastic, you can really use any plastic. If you are overmolding a plastic part with another plastic (or a rubber or TPE), then there can be compatibility issues. The material manufacturer typically publishes a compatibility chart for overmolding.