Cohesive Force
The frictional resistance that prevents parallel fibres from sliding past one another during drafting defines the structural integrity of a roving. Having high inter fiber cohesion prevents premature breakage of the flax strand on the drawing frames. This holding force is governed by the residual pectin on the fiber surface and the degree of fiber parallelization achieved during carding.
Mills must measure this force to maintain stable tension during yarn processing.
Drafting Influence
Mechanical draft on the drawing frame must overcome this internal friction to thin the roving without causing uneven drafting waves. If the inter fiber cohesion is too low, the roving splits under minimal tension, causing frequent machine stoppages. Conversely, excessive cohesion prevents the rollers from drawing the fibres smoothly, which creates thick, unspun slubs in the final yarn.
Mill technicians use a pulling test on the sliver to measure the force required to slide the fibres apart. This measurement dictates the load applied by the pressure rollers in the drafting zone.
Moisture Effect
Water application during the wet-spinning process modifies this resistance by softening the binding pectins between the flax fibres. Heat from the water bath allows the fibres to slide past one another with minimal resistance, enabling the production of very fine yarn counts. Wet spinning exploits this reduction in cohesion to achieve fine, uniform counts that dry-spun methods cannot replicate.
