Ends and Picks That Deliver a Target Weight in Linen
Target linen weight depends on yarn tex, ends, picks, and crimp contraction; calculating raw count without finishing shrinkage overshoots mass targets.
Yarn Cvm Irregularity
Variance Margin
The allowable tolerance for mass variation per unit length in drafted flax sliver is governed by capacitive testing protocols applied during the drawing frame stage at Chinese spinning mills. Measured capacitance fluctuations inside the testing head record local changes in linear density across the continuous ribbon before roving and final spinning operations begin. The resulting data populates the production quality sheet accompanying each batch toward export warehouses.
Application stops strictly at the mechanical drawing pass, leaving subsequent drafting zones and ring spinning tolerances to separate quality parameters. Excessive mass fluctuations trigger corrective drafting roll adjustments on the preceding flyer frame to restore uniform linear density.
Capacitive Profile
Fluctuations in mass density are detected by passing the drafted flax sliver through parallel capacitor plates where dielectric properties shift according to the amount of plant material present. Denser segments of the sliver alter the electrical field strength, producing proportional voltage signals that laboratory software converts into an unevenness index. Mill technicians compare these real-time signals against internal benchmark tolerances established for fine linen yarns rather than raw material grades.
Variations exceeding the allowable threshold indicate drafting instability in the preceding drafting rollers, demanding immediate mechanical calibration before export packaging takes place.
Export Classification
Final grading decisions rely upon the statistical distribution of mass deviations recorded during the capacitive test run, separating commercial export yarn from domestic utility stock. Quality inspectors evaluate the recorded coefficient of variation against the agreed purchase contract rather than the spinning mill internal standard, ensuring compliance with foreign buyer specifications. Exporters attach the certified testing report to the commercial invoice to satisfy international customs verification and quality guarantees.
Shipments failing the mass uniformity threshold undergo reprocessing through dedicated drafting machinery to recover acceptable linear density parameters prior to final container loading.