Distribution Analysis
Statistical measurement of the variation in length among individual flax fibres in a processed batch provides a baseline for spinning efficiency. The fiber length distribution determines the draft limits and the expected uniformity of the resulting linen yarn. Because flax is a bast fibre that undergoes hackling, the resulting population contains a mixture of long line fibres and short tow fibres.
Accurate plotting of these lengths helps the mill select the correct drafting zone settings.
Sorting Mechanic
Mechanical sorting instruments separate a representative sample of flax fibres into specific length classes to construct a frequency curve. In Chinese flax mills, laboratory technicians use a comb sorter or a photoelectric scanner to measure the proportion of fibres in each length interval. The resulting histogram shows the percentage of fibres that fall within each five-millimeter band.
When the distribution curve skews toward shorter lengths, the risk of drafting faults increases during spinning. Spun yarns from such batches display frequent thin spots and thick slubs. By adjusting the hackling pins, the mill can reduce this variation, leading to a more uniform output in the subsequent drawing frames.
Mill Influence
Spinning performance relies on keeping the proportion of short fibres below a defined threshold to prevent drafting irregularities. High variance in the length profile requires the spinning operator to adjust the draft roll distances or to blend the lot with more uniform fibres. The quality certificate for each flax consignment records the distribution parameters alongside the mean fibre length.
Contract terms use these curves to justify either a price premium or a discount on the incoming flax raw material.
