Melt Spinning
Denier is fixed by mass balance before the quench cabinet is reached.
— den
From throughput, hole count and take-up speed alone
Denier here is the nominal spun value from mass balance; the wound package will read slightly lower after any relaxation and slightly different again after drawing or texturing, so a measured skein count will not match this exactly. The filament diameter assumes a solid circular section - it is wrong for hollow, trilobal or other profiled spinnerets, where the same linear density corresponds to a larger circumscribed dimension. Die swell is not modelled: the extrudate expands on leaving the capillary before it attenuates, so the true maximum diameter exceeds the hole and the effective draw is greater than the ratio shown. The shear rate is the apparent Newtonian wall value and takes no account of entrance pressure losses, which for a short capillary can exceed the capillary loss itself.
Filament Denier, Spinneret Hole Throughput & Spin Draw Ratio — free, with the formula and a worked example, at Textile School.