Tube, Pipe & Profile Forming worked example

Ovality Tolerance Margin with actual roundness capability of the formed tube of 63 units: a worked example

Suppose actual roundness capability of the formed tube falls to 63 units. This page works the full calculation at that level so you can see exactly which result moves and by how much. Ovality Tolerance Margin tells a tube former how much roundness cushion sits between where a formed part actually lands and the ovality limit the drawing allows.

The inputs for this scenario

  • Actual roundness capability of the formed tube: 63 units (the input this scenario stresses; the baseline uses 125)
  • Ovality limit called out on the print: 100 units (held at the documented default)
  • Nominal tube diameter used as the reference: 100 units (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Ovality Tolerance Margin margin = available value - required value.
  • Margin works out to -37 % at these inputs, and this is the headline figure for the scenario.
  • Absolute margin works out to -37 value at these inputs.
  • Available amount works out to 63 value at these inputs.
  • Required amount works out to 100 value at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where actual roundness capability of the formed tube sits at 125 units and the headline result is 25 %, this scenario comes in 248% below the baseline at -37 %.
  • It computes the gap between your available ovality capability and the required ovality limit, then expresses that gap as a percentage of the nominal reference so you can compare it across part sizes. When the numbers land here, the stressed input is the lever to work; the walkthrough above shows exactly how much each output recovers as it climbs back toward the baseline.

Results at a glance

  • Margin: -37 % (headline result)
  • Absolute margin: -37 value
  • Available amount: 63 value
  • Required amount: 100 value

Run it with your numbers

  • To rerun this with your own numbers, open the live Ovality Tolerance Margin calculator, set actual roundness capability of the formed tube to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.