Building Materials Manufacturing worked example

Glass Annealing Time at 8.64% soak, cooling, and handling allowance: a worked example

Here is what the math looks like when conditions slip. We hold every other input steady and drop soak, cooling, and handling allowance to 8.64%, then walk the calculation through step by step. Estimate annealing time required for glass loads passing through a lehr or controlled cooling cycle.

The inputs for this scenario

  • Glass load requiring annealing: 1,200 tons (held at the documented default)
  • Annealing lehr or cycle release rate: 150 tons / hr (held at the documented default)
  • Soak, cooling, and handling 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 glass annealing time = glass load requiring annealing รท annealing lehr or cycle release rate.
  • Glass Annealing Time works out to 8.69 hr annealing time at these inputs, and this is the headline figure for the scenario.
  • Base glass annealing time works out to 8 hr annealing time at these inputs.
  • Soak, cooling, and handling allowance works out to 8.64 % at these inputs.
  • Annealing lehr or cycle release rate works out to 150 pieces / min at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where soak, cooling, and handling allowance sits at 12% and the headline result is 8.96 hr annealing time, this scenario comes in 3% below the baseline at 8.69 hr annealing time.
  • The practical read: the gap between this scenario and the baseline is entirely attributable to soak, cooling, and handling allowance, so recovering it is worth quantifying in dollars before considering equipment or staffing changes. It assumes a single steady release rate and a flat allowance; it does not model glass thickness, composition, or strain-point differences that change the required cooling curve for specific products.

Results at a glance

  • Glass Annealing Time: 8.69 hr annealing time (headline result)
  • Base glass annealing time: 8 hr annealing time
  • Soak, cooling, and handling allowance: 8.64 %
  • Annealing lehr or cycle release rate: 150 pieces / min

Run it with your numbers

  • To rerun this with your own numbers, open the live Glass Annealing Time calculator, set soak, cooling, and handling allowance to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.