Plastics Extrusion - Pipe, Film & Profile worked example
Screw RPM Throughput at 99% rate efficiency: a worked example
What does the result look like when rate efficiency reaches 99%? The full calculation is worked below with real intermediate numbers. Use it when a screw RPM change, material change, or new die setup needs a defensible pounds per hour estimate.
The inputs for this scenario
- Measured resin output: 1,200 lb (unchanged)
- Run time at screw setting: 8 hr (unchanged)
- Rate efficiency: 99 % (raised for this scenario; the documented default is 90)
Working through the calculation
- Applying the documented formula (Raw screw rpm throughput = measured resin output รท run time at screw setting) to the inputs above produces each figure below.
- At this operating point the engine returns 149 lb / hr for effective extruder throughput, the number this scenario is built around.
- At this operating point the engine returns 150 lb / hr for measured throughput before losses.
- At this operating point the engine returns 99 % for rate efficiency.
- At this operating point the engine returns 8 hr for run time at screw setting.
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 10% above the baseline at 149 lb / hr.
- A figure at this level is achievable when rate efficiency is genuinely sustained, not just peaked for a shift. A single weigh-and-time sample reflects one screw setting and resin; throughput shifts with melt temperature, resin lot, screen-pack loading, and back pressure.
Results at a glance
- Effective extruder throughput: 149 lb / hr (headline result)
- Measured throughput before losses: 150 lb / hr
- Rate efficiency: 99 %
- Run time at screw setting: 8 hr
Run it with your numbers
- Every input above is editable in the live Screw RPM Throughput calculator, which recalculates instantly and can be shared with the inputs intact.
Last reviewed 2026-05-12.