Fastener Manufacturing & Thread Rolling worked example

Washer Assembly Rate at 72% target washer assembly rate: a worked example

Here is what the math looks like when conditions slip. We hold every other input steady and drop target washer assembly rate to 72%, then walk the calculation through step by step. Calculate the washer assembly success rate for SEMS screws or captive washer fasteners against a target rate.

The inputs for this scenario

  • Fasteners with washer correctly assembled: 990 pieces (held at the documented default)
  • Total washer assembly attempts checked: 1,000 pieces (held at the documented default)
  • Target washer assembly rate: 72 % (the input this scenario stresses; the baseline uses 99.5)

Working through the calculation

  • The calculation starts from the formula this tool documents: Washer assembly rate = correctly assembled washer fasteners ÷ total attempts checked.
  • Washer assembly success rate works out to 99 % at these inputs, and this is the headline figure for the scenario.
  • Gap to washer target works out to -27 points at these inputs.
  • Correct assemblies works out to 990 count at these inputs.
  • Attempts checked works out to 1,000 count at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where target washer assembly rate sits at 99.5% and the headline result is 99 %, this scenario lands almost exactly on the baseline at 99 %.
  • The practical read: the gap between this scenario and the baseline is entirely attributable to target washer assembly rate, so recovering it is worth quantifying in dollars before considering equipment or staffing changes. It's only as good as the sample — a small or non-random inspection check won't reveal an intermittent feeder fault hiding in the unchecked population.

Results at a glance

  • Washer assembly success rate: 99 % (headline result)
  • Gap to washer target: -27 points
  • Correct assemblies: 990 count
  • Attempts checked: 1,000 count

Run it with your numbers

  • To rerun this with your own numbers, open the live Washer Assembly Rate calculator, set target washer assembly rate to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.