Some design would like to combine two different plastics, like many handles are designed with a soft grip on top of a hard plastic. It can be done by two-shot mold or insert molding. Two-shot molding or twin shot molding is a tooling that allows injection of two materials. After the first injection, the tooling will be rotated immediately for a second injection. Insert molding split the process by two sets of tooling. One set is to mold a base or called bare unit. The bare unit will then be put into a second tooling manually to mold a second plastic. The manually putting up the bare unit is an inserting process and therefore is called insert molding. Two-shot molding has strong bonding and more precision over insert molding. However, it needs to be molded by specially designed multi-shot injection machine. In general, insert molding is less costly than two-shot molding.
