How to Calculate Clamping Force for Injection Molding

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How to Calculate Clamping Force for Injection Molding

Image credit:  CustomPartNet

Image credit: CustomPartNet

Clamping force refers to the force applied to a mold by the clamping unit of an injection molding machine. In order to keep the mold closed, this force must oppose the separating force, caused by the injection of molten plastic into the mold.

Normally, the force rating is stated in tons, e.g. a 200 ton machine is capable of producing a maximum clamping force equivalent to a total of 200 tons. The calculated tonnage can be used to select a capable machine that will prevent part defects, such as excessive flash. So how much clamp force is required?

The required clamping force can be calculated from the cavity pressure inside the mold and the shot projected area, on which this pressure is acting.

There are variables that affect the clamping force calculation, like the material type (low-flow versus high-flow plastic), and the depth of the part.

For a thorough explanation of the calculation of clamping force, visit the Clamp Tonnage page of our website.

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