Weighing, Dosing & Loss-in-Weight Feeding calculator

Screw Feeder RPM From Catch Test Calculator

Estimate screw speed from a material-specific catch test. Enter test speed, measured flow, required flow and the qualified maximum screw speed.

What this calculator does

  • Estimate screw speed from a material-specific catch test.

Formula used

  • Mass per revolution = Test kg/hr ÷ (Test RPM × 60)
  • Required RPM = Test RPM × Required kg/hr ÷ Test kg/hr
  • Speed margin = Qualified maximum RPM − Required RPM

Inputs explained

  • Test Screw Speed: Measured screw speed during the reference catch test.
  • Measured Rate at Test Speed: Catch-test mass flow at the recorded screw speed.
  • Required Mass Feed Rate: Recipe rate to estimate within the tested operating range.
  • Qualified Maximum Screw Speed: Maximum speed approved for this feeder and material.

How to use the result

  • Best suited to feeder speed setup, material change catch tests.
  • Does not derive screw capacity from geometry or establish a safe drive limit.

Common questions

  • Can I use the motor nameplate RPM? Use actual screw RPM after gearbox reduction, not the motor shaft speed.
  • Why might doubling RPM not double mass flow? Screw filling, bulk density and flow behavior can change with speed and hopper conditions.
  • Does a positive margin prove the feeder is suitable? No. Torque, material handling, flow stability and the qualified minimum speed still require review.
  • Should I directly apply this as a calibration factor? No. It is a trial speed estimate; follow the controller procedure and verify the delivered rate.

Last reviewed 2026-10-12.