Melt Spinning

Spin Pump RPM & Melt Throughput Calculator

The pump meters volume; the order is written in kilograms. Melt density sits between the two, and it changes with the polymer.

Line Throughput Melt
kg/h
g/cm³

PET melt ≈1.2, PA6 ≈1.0, PP ≈0.75.

no.
Gear Pump Metering
cm³/rev
%
Polymer Flow behaviour
g/10 min
Pa·s·(g/10min)

Fitted to your own polymer and test conditions; not a physical constant.

Required Pump Speed

— rpm

To meter the line throughput at the stated efficiency

Flow & Rheology

Volumetric Melt Flow
— cm³/min
Mass Flow
— g/min
Throughput per Hole
— g/hole/min
Apparent Melt Viscosity
— Pa·s
Volume Displaced
— cm³/h

Apparent viscosity here is an inverse proportionality to melt flow index using a constant you supply — useful for tracking a polymer lot against its own history, not for comparing different polymers or predicting pack pressure. Volumetric efficiency falls as the pump wears, which is why a line slowly drifts light at a fixed set speed.

Spin Pump RPM & Melt Throughput Calculator — free, with the formula and a worked example, at Textile School.