Spinning Speed
Mechanical attenuation belongs to the drawing frame where flax slivers pass between successive pairs of rollers rotating at differential velocities. High-speed drafting increases the surface speed of the delivery rollers relative to the feed rollers, pulling parallel bast fibres into a more uniform ribbon before twist enters the roving. High-speed drafting generates high frictional heat within the drafting zone, which softens the residual pectin binding the ultimate cells together and prevents fibre breakage.
Excessive roller velocity tears the longer line flax staples, while insufficient speed leaves thick spots in the sliver that jam the spinning rings downstream. Machine operators adjust the weighted top rollers to maintain firm grip on the material, because loose control permits uncontrolled floating fibres to form slubs in the yarn.
Drafting Ratio
Linear extension is governed by the surface speed ratio between the back delivery pair and the front delivery pair, expressed as a numerical factor. High-speed drafting multiplies this length ratio beyond twelve to one for standard wet-spun flax, demanding precise mechanical settings to prevent sliver rupture. The delivery roller rotates faster than the supply roller, drawing the fibrous mass into a thinner strand without snapping the natural nodes characteristic of linen.
Mill technicians measure this ratio against the raw material grade, since harsh scutched flax requires lower extension rates than hackled line flax to preserve tensile strength. Calculations factor in the relative humidity of the spinning floor, because dry air increases static friction and causes the fibers to bunch during attenuation.
Yarn Uniformity
Mass variation along the spun thread determines the commercial grade of the final linen fabric, linking drawing performance directly to weaving quality. High-speed drafting reduces thick and thin places in the roving, producing an even yarn diameter that withstands high tension on the loom. Weavers test the finished yarn for imperfections on an optical board before releasing the lot for warp preparation.
Uneven drafting creates weak segments that snap during sizing, halting production and increasing waste rates across the entire mill floor. Final yarn strength depends entirely on how evenly the high-speed drafting zone parallelises the ultimate fibres without fracturing their natural structure.
