Clamping force calculation

The force needed to keep the mold closed is the product of the part’s projected area on the parting plane and the cavity pressure. Including a safety margin, it must stay below the machine’s clamping tonnage.

What is this calculation used for?

Finds the force the machine must apply to keep the mold closed without opening during injection. Used to answer “how many tons of machine do I need?” when selecting a new machine, or to check in advance whether a part will flash on an existing machine.

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How is it calculated?

  • Required tonnage = projected area (cm²) × cavity pressure (bar) × 1.0197 ÷ 1000 × (1 + safety margin)

Results are general engineering estimates; the machine catalog, material data sheet and trial run take precedence.

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