There are two important factors to calculate the clamping force: 1. Projected area S; 2. Cavity pressure P.
Plastics all have a viscosity (fluidity) grade, so there is a multiplicative constant K
Cavity pressure is determined by wall thickness and the ratio of flow to wall thickness:
P=P0•K (multiplicative constant)
Determination of clamping force (F):
F=P•S=P0•K•S