Ceramic, Tile & Sanitaryware Manufacturing worked example

Rework Firing Load Time at 8.64% rework sorting and kiln-change allowance: a worked example

Suppose rework sorting and kiln-change allowance falls to 8.64%. This page works the full calculation at that level so you can see exactly which result moves and by how much. Estimate added kiln or handling time required to refire rework tiles, reglazed ware, or repaired sanitaryware pieces.

The inputs for this scenario

  • Rework tiles or fixtures to refire: 1,400 pieces (held at the documented default)
  • Rework firing clearance rate: 18 pieces / min (held at the documented default)
  • Rework sorting and kiln-change allowance: 8.64 % (the input this scenario stresses; the baseline uses 12)

Working through the calculation

  • The calculation starts from the formula this tool documents: Base rework kiln time = rework pieces to refire รท rework firing clearance rate.
  • Required rework firing load time works out to 84.5 min at these inputs, and this is the headline figure for the scenario.
  • Base rework kiln time works out to 77.78 min at these inputs.
  • Rework firing allowance applied works out to 8.64 % at these inputs.
  • Rework firing clearance rate works out to 18 pieces / min at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where rework sorting and kiln-change allowance sits at 12% and the headline result is 87.11 min, this scenario comes in 3% below the baseline at 84.5 min.
  • It calculates the base kiln time to clear a rework batch at a given firing rate, then inflates it by a sorting and kiln-change allowance. 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

  • Required rework firing load time: 84.5 min (headline result)
  • Base rework kiln time: 77.78 min
  • Rework firing allowance applied: 8.64 %
  • Rework firing clearance rate: 18 pieces / min

Run it with your numbers

  • To rerun this with your own numbers, open the live Rework Firing Load Time calculator, set rework sorting and kiln-change allowance to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.