As mass production is continued using molds for plastic injection molding, the gas components generated from the plastic, soot, or moisture in the atmosphere gets accumulated on the surfaces of the metal parts or in the gaps between the nested division parts thereby becoming the causes of molding defects. Therefore, it is necessary to dismantle and clean the mold periodically. The disassembling and cleaning of molds is generally done according to the following procedure.

In order to make maintenance easy, it is wise to incorporate techniques at the time of designing the mold. Some ideas for this are given below.