Contact Tension
The mechanical resistance generated when wet linen roving wraps around a spinning frame cylinder constitutes capstan yarn friction, which dictates the twist gradient delivered to the wet flax drafting zone. Cylinder diameter and wrap angle determine the magnitude of this contact force, establishing the threshold where fibre slippage occurs instead of proper elongation. Mill technicians record these parameters on the daily wet spinning log before the bobbins move to the steam-heated drying tunnels.
Exceeding the optimal tension limit causes excessive filament breakage during drafting, while insufficient contact creates irregular yarn diameters across the bobbin height.
Drafting Ratio
Operating limits for wet spinning frames depend directly on how capstan yarn friction restrains the moving ribbon of flax fibres between the feed rollers and the delivery rollers. Raw material variability requires constant adjustment of the weighted top rollers to maintain uniform draft resistance without fracturing the delicate plant cell walls. Plant floor operators consult the internal mill standard for wet spinning rather than the buyer acceptance specification when calibrating these mechanical weights.
Excessive moisture retention increases drag across the metal surfaces, forcing operators to reduce frame speeds to prevent yarn stretching beyond the elastic limit of the cellulose.
Export Grade
Final quality verification of finished flax yarn relies on laboratory dynamometers measuring breaking load and elongation percentages against international linen merchant rules. Buyers specify maximum allowable breaking length variations in the purchase contract, and the mill laboratory issues a certificate of analysis for every lot leaving the warehouse. Fibre grades derived from retted flax straw determine the baseline tensile strength, whereas finished fabric grades reflect the total absence of spinning irregularities caused by improper drafting tension.
Strict adherence to these export thresholds ensures that woven linen textiles maintain uniform warp and filling density throughout the commercial dyeing and finishing processes.
