Grain Milling, Dry Bulk Food & Feed Handling worked example

Screen Change Impact at 60% post-change milling efficiency: a worked example

Suppose post-change milling efficiency falls to 60%. This page works the full calculation at that level so you can see exactly which result moves and by how much. Estimate the throughput impact of a hammer mill, screener, or classifier screen change using post-change output, runtime, and expected efficiency.

The inputs for this scenario

  • Output after screen change: 96 tons (held at the documented default)
  • Runtime on new screen: 8 hr (held at the documented default)
  • Post-change milling efficiency: 60 % (the input this scenario stresses; the baseline uses 84)

Working through the calculation

  • The calculation starts from the formula this tool documents: Raw screen-change throughput = output after screen change รท runtime on new screen.
  • Effective throughput works out to 7.2 tons / hr at these inputs, and this is the headline figure for the scenario.
  • Raw screen-change throughput works out to 12 tons / hr at these inputs.
  • Efficiency works out to 60 % at these inputs.
  • Runtime works out to 8 hr at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where post-change milling efficiency sits at 84% and the headline result is 10.08 tons / hr, this scenario comes in 28.57% below the baseline at 7.2 tons / hr.
  • It computes the effective tons-per-hour a line runs on a newly installed screen by dividing post-change output by post-change runtime and derating by the resulting milling efficiency. 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

  • Effective throughput: 7.2 tons / hr (headline result)
  • Raw screen-change throughput: 12 tons / hr
  • Efficiency: 60 %
  • Runtime: 8 hr

Run it with your numbers

  • To rerun this with your own numbers, open the live Screen Change Impact calculator, set post-change milling efficiency to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.