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Clamping Force Calculator

Work out clamping force instantly with clear inputs, formula shown and shareable results.

About Clamping Force Calculator

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.

Formula

Clamping force

F newtons = projected area cm² x cavity pressure bar x 10 x (1 + margin)

Worked example

With the default values below, Clamping Force Calculator returns Clamping force required of 47.1. Change any input above and every figure here is recalculated in your browser.

Inputs used

Projected area of part and runnersminimum 0.1 cm²
120 cm²
Average cavity pressureminimum 10 bar
350 bar
Safety marginaccepts 0–50 %
10 %

Results

Clamping force required
47.1 t
Clamping force
462.0 kN
Force per square centimetre
0.393 t/cm²
Machine size to specify
50 t

Step by step

  1. 1Values used
  2. 2Clamping force
  3. 3Clamping force required= 47.1 t
  4. 4Clamping force= 462.0 kN
  5. 5Force per square centimetre= 0.393 t/cm²
  6. 6Machine size to specify= 50 t

Assumptions and limits

  • The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is the Clamping Force figure worked out?

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.

What happens if clamp force is short?

The mould breathes open at the parting line and flash forms. Persistent flashing peens the parting surfaces and eventually ruins the tool.

What values do I need to enter?

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.

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