Fastener Manufacturing & Thread Rolling worked example

Inspection Sample Size at 110% sampling coverage factor: a worked example in fastener manufacturing & thread rolling

What does the result look like when sampling coverage factor reaches 110%? The full calculation is worked below with real intermediate numbers. Use it when planning QA workload for dimensional, thread, torque, proof-load, plating thickness, or visual inspection on fastener lots.

The inputs for this scenario

  • Samples required per inspection point: 13 samples (unchanged)
  • Inspection points or lots: 24 points (unchanged)
  • Sampling coverage factor: 110 % (raised for this scenario; the documented default is 100)
  • First-pass acceptance factor: 96 % (unchanged)

Working through the calculation

  • Applying the documented formula (Gross inspection samples = samples per inspection point × inspection points or lots) to the inputs above produces each figure below.
  • At this operating point the engine returns 329 units for good output capacity, the number this scenario is built around.
  • At this operating point the engine returns 312 samples for gross sample checks.
  • At this operating point the engine returns -31.2 samples for coverage reduction.
  • At this operating point the engine returns 13.73 samples for retest or rejection allowance.

How this compares with the baseline

  • Against the tool's baseline example, where sampling coverage factor sits at 100% and the headline result is 300 units, this scenario comes in 10% above the baseline at 329 units.
  • A figure at this level is achievable when sampling coverage factor is genuinely sustained, not just peaked for a shift. It models a fixed-rate plan, so it won't follow a switching rule (tightened-normal-reduced) or recompute when a lot fails and triggers 100% sort.

Results at a glance

  • Good output capacity: 329 units (headline result)
  • Gross sample checks: 312 samples
  • Coverage reduction: -31.2 samples
  • Retest or rejection allowance: 13.73 samples

Run it with your numbers

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

Last reviewed 2026-05-12.