Tunnel Boring & Heavy Civil Equipment worked example

Rework Cost at 81% reject rate applied: a worked example in tunnel boring & heavy civil equipment

Push reject rate applied up to 81% and the picture changes. This example computes every intermediate figure at that operating point. Use it when a weld-inspection report flags failures to budget the gouge-out, re-weld, and NDT recall before the assembly can be released.

The inputs for this scenario

  • Defective Weld Joints: 60 joints (unchanged)
  • Repair Cost per Joint: 950 $/joint (unchanged)
  • Reject Rate Applied: 81 % (raised for this scenario; the documented default is 70)
  • Re-Inspection Setup: 12,000 $ (unchanged)

Working through the calculation

  • Applying the documented formula (Total = defective joints x repair cost x (reject rate รท 100) + re-inspection setup) to the inputs above produces each figure below.
  • At this operating point the engine returns 58,170 $ for total rework cost, the number this scenario is built around.
  • At this operating point the engine returns 970 $ / piece for rework cost per unit.
  • At this operating point the engine returns 46,170 $ for variable rework cost.
  • At this operating point the engine returns 12,000 $ for fixed rework cost adder.

How this compares with the baseline

  • Against the tool's baseline example, where reject rate applied sits at 70% and the headline result is 51,900 $, this scenario comes in 12.08% above the baseline at 58,170 $.
  • It computes the total cost of a weld rework batch as the variable per-joint repair cost times the effective reject rate, plus a fixed re-inspection setup, and the cost per defective joint. The value of this scenario is the size of the gap it exposes: that gap, priced out over a year, is the budget you can justify spending to close it.

Results at a glance

  • Total rework cost: 58,170 $ (headline result)
  • Rework cost per unit: 970 $ / piece
  • Variable rework cost: 46,170 $
  • Fixed rework cost adder: 12,000 $

Run it with your numbers

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

Last reviewed 2026-05-12.