Injection molding screw parts are necessary for plastic […]
Injection molding screw parts are necessary for plastic injection molding. They provide the proper mixing of molten plastic before tip assembly. During this process, plastic is introduced to the screw and barrel, and then slides on the inside surface of the barrel. Once in the transition section, it undergoes further compression, nearly melting. It is then directed to the mold.
Injection molding screw parts can be made with side-action cores. These cores slide into the part cavity from the side, making it possible to mold the internal and external undercuts and threads. The side-action cores can also be equipped with a lifting device that allows for internal undercut molding.
Side-action cores have two basic methods: the heel block backup and the cam pin method. This method is ideal, because it can result in the ideal fit with the part when closed. It is also limited by steel, which tends to change shape during injection. However, it is possible to use a collapsible core action to create threaded parts.
This system allows moldmakers to eliminate the need for external adjustments and setups. The cylinder can be set and pulled with the mold closed, or set and pulled before closing. In either case, full hydraulic pressure is maintained throughout the injection process.