Injection Molding worked example

Clamp Tonnage with total projected area of 23 sq in: a worked example

This worked example runs the clamp tonnage numbers for a tougher week than the baseline: total projected area of 23 sq in instead of the typical 45 sq in. Calculate required clamp force from projected part area, average cavity pressure, and a safety factor for flash prevention.

The inputs for this scenario

  • Total projected area (all cavities): 23 sq in (the input this scenario stresses; the baseline uses 45)
  • Average cavity pressure: 4,500 psi (held at the documented default)
  • Safety factor: 1.15 x (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Required clamp force = Projected area x Average cavity pressure x Safety factor.
  • Result works out to 119,025 tons at these inputs, and this is the headline figure for the scenario.
  • Raw clamp force (area x pressure) works out to 119,025 value at these inputs.
  • Multiplier works out to 1 x at these inputs.
  • Factor A x B works out to 103,500 value at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where total projected area sits at 45 sq in and the headline result is 232,875 tons, this scenario comes in 48.89% below the baseline at 119,025 tons.
  • Use it when selecting a press for a new mold, transferring a tool between machines, or troubleshooting flash that suggests the part is undersized on tonnage. A result at this level usually justifies acting on the stressed input before touching anything else, because every other figure in the table is downstream of it.

Results at a glance

  • Result: 119,025 tons (headline result)
  • Raw clamp force (area x pressure): 119,025 value
  • Multiplier: 1 x
  • Factor A x B: 103,500 value

Run it with your numbers

  • To rerun this with your own numbers, open the live Clamp Tonnage calculator, set total projected area to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.