The higher the press tonnage, the larger the machine and the more expensive it is to run. The tonnage calculator estimates the required clamping force based on part specification. Clamping force is required to keep the mold shut, resisting the injection pressure required to fill the mold with molten plastic. To estimate the required clamping force the total projected area of the part is multiplied by the required cavity pressure. This will give you a starting point for required tonnage.
