Metals, Steel, Aluminum & Coil Processing worked example

Metal Thickness Window with thickness tolerance band of 10 mils: a worked example

What does the result look like when thickness tolerance band reaches 10 mils? The full calculation is worked below with real intermediate numbers. Use it when a quality manager wants a fast in-spec check on gauge before the coil moves to the next process.

The inputs for this scenario

  • Thickness tolerance band: 10 mils (raised for this scenario; the documented default is 4)
  • Measured deviation: 2 mils (unchanged)
  • Reserve buffer: 1 mils (unchanged)

Working through the calculation

  • Applying the documented formula (Remaining tolerance = thickness tolerance band - measured deviation - reserve buffer) to the inputs above produces each figure below.
  • At this operating point the engine returns 0 outside for inside window, the number this scenario is built around.
  • At this operating point the engine returns -8 value for nearest margin.
  • At this operating point the engine returns 2 value for lower limit.
  • At this operating point the engine returns 1 value for upper limit.

How this compares with the baseline

  • Against the tool's baseline example, where thickness tolerance band sits at 4 mils and the headline result is 0 outside, this scenario lands almost exactly on the baseline at 0 outside.
  • A figure at this level is achievable when thickness tolerance band is genuinely sustained, not just peaked for a shift. It treats deviation as a single worst-case number; it does not model a varying thickness profile across the strip width.

Results at a glance

  • Inside window: 0 outside (headline result)
  • Nearest margin: -8 value
  • Lower limit: 2 value
  • Upper limit: 1 value

Run it with your numbers

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

Last reviewed 2026-05-12.