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Calcimator

Clamp Force Calculator

Calculate required clamping tonnage from projected part area, cavity pressure, and number of cavities.

Inputs

in²
psi

Results

Required Clamp Force

132 US tons

Clamp Force1,174.3 kN
Clamp Force119.8 metric tons
Total Projected Area48 in²
Force per Cavity33 tons
Recommended Machine Size150 tons
How to Use This Calculator
  1. Enter projected part area per cavity (in²) — measure on the parting line plane in your CAD model.
  2. Set cavity pressure (PSI) based on material and part geometry — typically 5,000–15,000 PSI.
  3. Enter number of cavities in the mold.
  4. Review required clamp force (tons and kN) and confirm your press has sufficient clamping tonnage.
  5. Add 10–15% safety margin above the calculated requirement when selecting the press.

How the result changes with Projected Area per Cavity

Projected Area per CavityRequired Clamp Force
5005,500 US tons
1,75019,250 US tons
3,25035,750 US tons
4,50049,500 US tons

What each input means

Projected Area per Cavity
Projected area of the part (and runner) onto the parting plane per cavity.
Cavity Pressure
Average cavity pressure during injection (typically 3,000-15,000 psi).
Number of Cavities
Number of cavities in the mold.
Safety Factor
Safety multiplier for clamp force (typically 1.1-1.2).

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Projected Area per Cavity = 12, Cavity Pressure = 5000, Number of Cavities = 4, Safety Factor = 1.1 = 4 input(s) provided
  2. Calculate Required Clamp Force
    Required Clamp Force
    132 = 132
  3. Calculate Clamp Force
    Clamp Force
    1174.3 = 1174.3
  4. Calculate Clamp Force
    Clamp Force
    119.8 = 119.8

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