Injection Molding worked example

Mold Trial Sample Size with number of cavities in mold of 4 cavities: a worked example

This worked example runs the mold trial sample size numbers for a tougher week than the baseline: number of cavities in mold of 4 cavities instead of the typical 8 cavities. Calculate the minimum sample size needed for a mold trial or process validation based on confidence level and expected variation.

The inputs for this scenario

  • Number of cavities in mold: 4 cavities (the input this scenario stresses; the baseline uses 8)
  • Minimum shots per cavity for confidence: 30 shots (held at the documented default)
  • Inspection multiplier (characteristics or repeats): 1 x (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Total sample size = Cavities x Shots per cavity x Inspection multiplier.
  • Result works out to 120 parts at these inputs, and this is the headline figure for the scenario.
  • Cavities x Shots per cavity works out to 120 value at these inputs.
  • Multiplier works out to 1 x at these inputs.
  • Factor A x B works out to 120 value at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where number of cavities in mold sits at 8 cavities and the headline result is 240 parts, this scenario comes in 50% below the baseline at 120 parts.
  • Use it when planning a tool trial, first-article run, or process validation so you reserve enough material and press time. 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: 120 parts (headline result)
  • Cavities x Shots per cavity: 120 value
  • Multiplier: 1 x
  • Factor A x B: 120 value

Run it with your numbers

  • To rerun this with your own numbers, open the live Mold Trial Sample Size calculator, set number of cavities in mold to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.