The clamp force is the maximum force required to keep the mold closed during filling. This force can be calculated.

The clamp force predictions for a part can then be compared with the clamp force limit of the injection molding machine to be used.

## Clamp force calculation

The calculated maximum clamp force is a function of injection pressure and the projected area of the part. The projected area is the area of the model that is projected onto the XY plane. For the clamp force calculations to be correct, the model must be positioned so that the clamp force is applied along the Z axis direction as shown in the following diagram.

Note: Although clamp force planes can be changed from the default Z axis using the custom plots wizard, all solver calculations are still based on the Z direction.

Clamp force is also calculated during the packing stage when the whole cavity might be pressurized to a higher value than it was during the filling stage.