It work by injecting melted plastic into a clamp that contains a mold, with the end shape produced being a reverse image of the mold in the clamp.

These machines are ideal for both simple and intricate plastic parts with great detail. Machine styles include electric, hydraulic, toggle and hybrid, dual shot, and multi-shot.

It can be used to produce a product with a product with an insert introduced so the plastic is molded around the insert. Examples of this would be screwdrivers and electrical components. Vertical injection molders are usually configured with either a shuttle table or rotary table to convey the mold.