Over molding is the process of molding two different materials, one on top of, or around the other. The top or outer layer is typically a plastic of some sort. This process results in a single structure that has one desired characteristic, function, color or shape on the inside, and a different, often more ergonomic or aesthetic characteristic on the inside.
There are numerous applications for the over-molding process since it is common for products to have a specific function that requires one set of physical characteristics, while having a different set of requirements to make it easy to use, or rugged enough to withstand normal usage or environmental conditions.
Typical examples of contract over-molding projects Axcesor undertakes include a broad selection of instruments, and particularly for the medical industry. It is common to have sensors, diagnostic capability or embedded controls close to a patient but not within the instrument itself, and yet be impractical to house it in a cabinet.
In the image above, the central part is a PCBA that has been over-molded to protect it from abrasion, shock, liquids and potential electrical interference induced by direct contact. The PCBA is set in a mold cavity which is closed, and an over molding product is injected at low pressure into the mold so it surrounds the part. Low pressure is desirable to insure that none of the components on the PCBA are disturbed. The result is a solid protective shell that simultaneously provides close proximity to the work area and protection.
Other highly common applications include all types of electrical cable termination and encapsulation. In this instance, the contract service includes procurement of a specified set of cables, terminations of the conducting wires, and over-molding desired connector shapes to provide compact, secure, custom connector for a dedicated piece of equipment.