Work out clamping force instantly with clear inputs, formula shown and shareable results.
Melt pressure inside the cavity tries to force the mould open across the whole projected area, so clamp force is projected area times cavity pressure. One bar acting on one square centimetre is 10 newtons, which makes the arithmetic direct. Typical cavity pressures run 200-500 bar depending on wall thickness and flow length.
Clamping force
F newtons = projected area cm² x cavity pressure bar x 10 x (1 + margin)
F newtons = projected area cm² x cavity pressure bar x 10 x (1 + margin). Melt pressure inside the cavity tries to force the mould open across the whole projected area, so clamp force is projected area times cavity pressure.
The mould breathes open at the parting line and flash forms. Persistent flashing peens the parting surfaces and eventually ruins the tool.
This calculator takes 3 inputs: Projected area of part and runners, Average cavity pressure, Safety margin. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.