The components in the plastic injection mold

A mold is a tool used for parts that fit the design we want (shape & dimension). Another definition, mold (mold) is a cavity that has a certain shape (according to the design) in order to make the product in quick time in one stage and cheap. Because making this mold is very expensive, usually making a mold is done to mass produce. Construction of base material consists of hardened steel, pre-hardened steel, aluminum alloy & beryllium copper. However, selection of different molding materials is indispensable with mold (shot with “shot”). Meanwhile, check out the injection mold manufacturer china as well.

In general, the components of the mold can be described as follows:


Mold is formed from 2 parts of cavity and core. In injection molding, both are inseparable entities, because the combination of cavity and core is what will form the design of a component.


These three parts, sprue, runner & gate are channels to drain the injected plastic melt from the engine nozzle into the mold. Why is the hot plastic melt coming out of the nozzle mouth not directly flowed into the mold? The answer is to maintain the quality of the part (avoid flushing, jetting, weld line, burn marks, etc.) to get the desired dimensions and shape of the part.

Sprue: is the main connecting channel embedded in the fixed plate of a mold and directly in contact with the nozzle tips. The manufacturing process is embedded in the mold block.

Runner: Right position is on the dividing line (parting line). is a continuation channel after the sprue and serves to prevent a decrease in temperature and pressure when the molten plastic enters the mold. In addition, the shape, position, and a number of cavities will directly affect the pressure and temperature drop in the mold.

Gate: Gate is the last channel that directly in contact with the material. function: control the direction and flow of material, simplify the material finishing process (gate hrs separated/cut from the finished product) and prevent counterflow from the mold into the nozzle during cooling.