Injection Molding Machines. Functions and Design Solutions

Plastic injection molding involves filling the cold cavities of a mold with molten plastic, then demolding the resulting part once the plastic has cooled and solidified.

The mould cavities are filled by introducing molten plastic material under pressure into the mould cavities.

The temperature of the cavities is regulated to a value that cools the injected material.

The injection-molded parts, formed by the plastic material solidified in the cavities, are extracted from the mold by means of a mold opening and an ejection device.

The cost price of injected parts is closely linked to the hourly cost of the machine and its technical performance. These technical performances must be adapted to the complexity of the part to be produced (geometry, tolerances and material processed) and depend on the solutions adopted by injection molding machine manufacturers.

This article presents the constructive solutions adopted by the machine manufacturers on the market. The comments accompanying the descriptions will help the reader choose the optimum solution for his application. It is followed by two other articles:

• [AM 3 672] Injection molding machines. Features and architecture, which details the architectures, features and areas of use of conventional and special presses;

• [AM 3 673] Injection molding machines. Machine selection and process optimization, where the reader will find sizing, adjustment and optimization methods.