Flax Fibre Bundle Separation and Staple Length Retention Fundamentals
Selective pectin degradation paired with tuned hackling pin density maximizes fibre bundle separation while retaining staple length for fine wet spinning.
Draw Frame Ratch
Machine Setting
The physical distance between the nips of the drawing rollers in a bast fiber preparation machine determines the control of fibers during drafting. Setting the draw frame ratch requires precise adjustment based on the maximum fiber length in the sliver. If the distance is too narrow, the rollers crush and break the long flax fibers, whereas an excessive distance allows short fibers to float, causing thick and thin sliver defects.
Mechanical Performance
Fluctuations in the drawing process are minimized when the mechanical settings match the fiber length distribution. An incorrect draw frame ratch causes drafting waves, where groups of fibers move together uncontrolled through the drafting zone. Spun yarns produced from such defective slivers exhibit high coefficient of variation in mass, which translates to frequent breaks during weaving.
Yield Control
Mill laboratory testing verifies sliver evening rates and drafting force profiles during every shift. To maintain the draw frame ratch at its optimal value, technicians measure the span of the longest five percent of fibers in the sliver block. When yarn spinners process wet-treated flax or blended slivers, they adjust this distance to balance the friction between the synthetic and natural fibers.
This prevention of fiber slippage secures consistent linear density across the entire yarn run, which is recorded in the final inspection document of the mill. This consistency ensures that the resulting linen fabrics meet the global standards for tensile strength.