Mold clamping force is an important parameter of injection molding machine, which reflects a machine’s processing capacity of plastic parts to a certain extent. In the design of a new mold, it is necessary to determine an injection molding machine with proper mold clamping force.

 

Definition:

Mold clamping force is the maximum clamping force exerted on the die by injection molding machine, also called die clamping force. At the time of injection, the melt is compressed through the screw or plunger, and enters the mold cavity through the nozzle. Excepting a part of the pressure loss on the nozzle and the runner, the remaining pressure is referred to as the cavity pressure. In order to keep the cavity pressure to the top of the mould, the clamping force must be exerted enough clamping force.

 

 

Calculation:

F＝K×p×A

F: mold clamping force, N;

K: safety factor, generally take about 2;

P: cavity pressure, Pa;

A: the sum of the projected areas, m².

 

Significance:

It is very important to choose the clamping force for forming a plastic part. Lack of clamping force can cause the mold to leave the seam and overflow, and the molded parts will also produce flying edges. But when the force is too large, the mold will deformation, and the plastic parts will produce internal stress and cause unnecessary energy consumption.

 

The clamping force produced by the system is certain. However, due to the contact between the nozzle and the mold and the bulging action of the melt pressure during injection, mold clamping force varies during an injection molding cycle. In the actual injection molding process, the plastic parts, the plastic used, the process conditions and the structure of the mold are different, so the actual mold clamping force is different.