Plastics Extrusion - Pipe, Film & Profile worked example

Screw RPM Throughput at 65% rate efficiency: a worked example

Suppose rate efficiency falls to 65%. This page works the full calculation at that level so you can see exactly which result moves and by how much. Estimate effective extruder throughput from measured pounds produced, run hours, and a realistic screw speed efficiency factor.

The inputs for this scenario

  • Measured resin output: 1,200 lb (held at the documented default)
  • Run time at screw setting: 8 hr (held at the documented default)
  • Rate efficiency: 65 % (the input this scenario stresses; the baseline uses 90)

Working through the calculation

  • The calculation starts from the formula this tool documents: Raw screw rpm throughput = measured resin output รท run time at screw setting.
  • Effective extruder throughput works out to 97.5 lb / hr at these inputs, and this is the headline figure for the scenario.
  • Measured throughput before losses works out to 150 lb / hr at these inputs.
  • Rate efficiency works out to 65 % at these inputs.
  • Run time at screw setting works out to 8 hr at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where rate efficiency sits at 90% and the headline result is 135 lb / hr, this scenario comes in 27.78% below the baseline at 97.5 lb / hr.
  • It computes raw screw throughput as measured resin output divided by run time, then an effective throughput after applying a rate-efficiency factor. 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 extruder throughput: 97.5 lb / hr (headline result)
  • Measured throughput before losses: 150 lb / hr
  • Rate efficiency: 65 %
  • Run time at screw setting: 8 hr

Run it with your numbers

  • To rerun this with your own numbers, open the live Screw RPM Throughput calculator, set rate efficiency to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.