Injection Molding worked example

Clamp Tonnage with total projected area of 110 sq in: a worked example

Push total projected area up to 110 sq in and the picture changes. This example computes every intermediate figure at that operating point. Use this when selecting a press for a new mold, verifying that an existing machine has enough clamping force, or quoting tooling with a specific tonnage requirement.

The inputs for this scenario

  • Total projected area (all cavities): 110 sq in (raised for this scenario; the documented default is 45)
  • Average cavity pressure: 4,500 psi (unchanged)
  • Safety factor: 1.15 x (unchanged)

Working through the calculation

  • Applying the documented formula (Required clamp force = Projected area x Average cavity pressure x Safety factor) to the inputs above produces each figure below.
  • At this operating point the engine returns 569,250 tons for result, the number this scenario is built around.
  • At this operating point the engine returns 569,250 value for raw clamp force (area x pressure).
  • At this operating point the engine returns 1 x for multiplier.
  • At this operating point the engine returns 495,000 value for factor a x b.

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 144% above the baseline at 569,250 tons.
  • It estimates the required clamp force by multiplying total projected area by average cavity pressure and a safety factor, giving the press tonnage needed to hold the mold closed. The value of this scenario is the size of the gap it exposes: that gap, priced out over a year, is the budget you can justify spending to close it.

Results at a glance

  • Result: 569,250 tons (headline result)
  • Raw clamp force (area x pressure): 569,250 value
  • Multiplier: 1 x
  • Factor A x B: 495,000 value

Run it with your numbers

  • Every input above is editable in the live Clamp Tonnage calculator, which recalculates instantly and can be shared with the inputs intact.

Last reviewed 2026-05-12.