Plastic mold
The plastic mold is the tool for injection molding: a closed steel mold into which the plastic is injected. Its surface determines the quality of the part – therefore it is mirror-polished and must be corrosion- and wear-resistant.
What a plastic mold is
The plastic mold is half of the injection mold tool: a milled, polished steel mold that gives the plastic part its shape. Two mold halves close, plastic is injected, cools, and the mold opens.
The special requirements
Unlike a die-casting mold, the plastic mold isn't under brutal thermal shock, but surface quality matters much more. It must be able to be polished to a high gloss, hold dimensions, and stay corrosion-resistant with aggressive plastics.
Typical materials
Plastic molds are made from pre-hardened mold steels like 1.2738 or 1.2311, and for corrosion requirements from 1.2316. Large molds require grades that are easy to machine and harden through.