Injection molding requires an injection press.
The injection press has a screw and barrel, which allows the machine to produce a great deal of heat required in this process. It can also relieve air and other problems otherwise seen in conventional molding.
The tool can be under great pressure to keep closure tolerances, requiring tooling to be more precise.
Material is injected into the tool from the barrel into the closed tool.
Feed systems can often times create less waste than transfer molding.
A consideration to injection molding is that the molding press can be more expensive and require more maintenance.