Plastic injection molding is the preferred process for manufacturing plastic parts. Injection molds are used to create many things such as electronic housings, containers, bottle caps, automotive interiors, pocket combs, and most other plastic products available today. Plastic injection molds are ideal for producing high volumes of plastic parts, due to the ability of making multi-cavity injection molded parts, where multiple parts are made with one cycle. Some advantages of injection molding are high tolerances, repeatability, a wide range of material selection, low labor cost, minimal scrap losses, and little need to finish parts after molding. Some disadvantages of this process include an expensive tooling investment and the need to prototype, as some custom complex parts may encounter problems during the injection molding process such as warp or surface defects. Therefore, injection molded parts must be designed with careful molding consideration.
Most polymers may be used for molds, including all thermoplastics, some thermosets, and some elastomers. There are tens of thousands of different materials available for injection molds and that number is increasing every year. The materials can mixed with alloys or blends of previously developed materials. This allows product designers to choose from a vast selection of materials so they can choose exactly the right properties for the injection molded part or parts they need. Mold materials are chosen based on the strength and function required for the final part and each material has different parameters for molding that must be considered. Common polymers like Epoxy and phenolic are examples of thermosetting plastics while nylon, polyethylene, and polystyrene are thermoplastic.