Drafting Resistance
A mechanical force generated during the attenuation of a fiber strand opposes the relative movement of individual fibers as they pass through the drafting rollers. During the spinning of linen yarn from flax fibers, dynamic drafting friction influences how evenly the roving is drawn out in the draft zone. This frictional force depends on the fiber surface characteristics, the moisture content, and the amount of natural wax remaining on the flax.
Spinners monitor this parameter because it dictates the draft force required to achieve the target yarn count. If the resistance becomes too high, the fibers will clump rather than slide smoothly, resulting in drafting waves and uneven areas in the output.
Process Variation
A fluctuation in the drawing force leads to thick and thin places in the spun yarn. High dynamic drafting friction causes the strand to break under tension during high-speed drawing. Spinning mills regulate the relative humidity of the spinning room to maintain a stable moisture level in the flax fibers, which directly controls the friction.
By keeping the moisture constant, the mill ensures that the drafting process operates within the specified limits.
Yarn Strength
A stable drawing resistance prevents yarn defects that would otherwise cause breakage during subsequent weaving. When dynamic drafting friction is kept uniform, the resulting linen yarn exhibits high tensile strength and a low coefficient of variation. This consistency is recorded on the laboratory test report for each spun lot.
