Fibre Impurity Measurement
Quantification of entanglements within carded flax sliver provides the primary metric for assessing yarn consistency prior to spinning. This nep count identifies the frequency of small knot-like clusters of short fibres that arise during the mechanical cleaning of scutched material. Production managers record these findings in the quality control log for each batch before the sliver reaches the drawing frame.
Accurate data collection ensures that spinning frames do not suffer from frequent end breakage during the conversion of flax into roving.
Production Calibration
Technicians perform this assessment through the visual inspection of thin webs produced at the carding stage or through automated optical scanning devices that pass the sliver between a light source and a sensor. The software registers an interruption in opacity and assigns a value based on the density of the obstruction. A high frequency of these entanglements suggests that the carding wire settings require adjustment to remove short fibres or to reduce friction against the metallic surfaces.
Excessive speed at the carding cylinders creates unnecessary trauma to the fibre, causing the material to cluster rather than align in a parallel fashion. Mill specifications define the acceptable threshold for these faults depending on the final application, such as high-density shirting or industrial canvas. The buyer acceptance criteria differ from internal mill standards because buyers mandate a lower tolerance for surface irregularities that remain visible after finishing.
Spinning Consequence
Mechanical failure occurs when these clusters enter the drafting zone because the small knots act as rigid bodies that disrupt the steady flow of parallelised fibre. Spinning machinery lacks the capability to incorporate these knots into the yarn structure without creating thin spots that weaken the tensile strength of the finished product. Woven cloth exhibits surface defects if the sliver contains an excessive number of these knots.
Each defect persists through the weaving process and creates a permanent flaw in the grey goods. The removal of knots at the carding stage remains the only viable method for improving yarn uniformity.
