There are two main components of an injection molding machine: the clamping unit and the injection unit. The clamping unit opens and closes a mold, while the injection unit manipulates the melted plastic to the shape of the mold.
The clamping unit uses toggles to open and close the mold, while the injection unit has a screw that melts the plastic, accumulates it in front of the screw, and then injects it into the mold.

Temperature Control Units
The temperature of the melted plastic can affect how it fills the mold cavities and how it cools once it’s inside. Injection machines usually have temperature control units, or TCUs, that circulate a steady flow of coolant through the passages in the mold tool to maintain correct internal temperatures.