Injection molding machine clamping force is to lock mould the maximum said, injection inside the molding cavity material pressure is to open mould’s direction, it must be low clamping force, usually material pressure must in lower than 80% of the clamping force. Forming space unit area average space according to injection institutions, plunger about 400-500kg/cm, screw about 250-350kg/cm.
1 、Empirical formula:
Clamping force=forming space unit area average space * forming space projected area * coefficient
=330kg/cm product length * product wide*1.5

Note: 1) Product  length、wide unit is cm;

          2) Calculated the clamping force unit is kg, divided by 1000 is the injection molding machine tonnage (T);

          3) Product’s forming space projected area, such as the box type product, after spread the product box, then to amount it length and wide.

2、 After calculate the required tonnage of the injection molding machine, then according to calculated results to choose the injection molding machine ( injection molding machine tonnage must be larger than this calculated results), but should pay attention to the injection molding machine maximum and minimum mould thickness, mould maximum  length and wide size must smaller than the selected injection molding machine distance, the mould height must between in the selected injection molding machine maximum and minimum mould thickness.