Basics of Injection Molding Making polymers is a fantastic science. One of the most common methods of shaping plastic resins is a process called injection molding.
Injection molding is accomplished by large machines called injection molding machines.
Resin is fed to the machine through the hopper. Colorants are usually fed to the machine directly after the hopper. The resins enter the injection barrel by gravity though the feed throat. Upon entrance into the barrel, the resin is heated to the appropriate melting temperature. The resin is injected into the mold by a reciprocating screw or a ram injector.