Quantifying Wet Spinning Limits for Low Cohesion Bast Fiber Slivers
Low cohesion flax slivers collapse under high draft ratios, requiring reduced trough temperatures, higher roving twist, and tight ratch settings to hold count.
Dynamic Drag Force
Tension Measurement
Resistance encountered by a flax strand as it is drawn through a wet treatment bath or over guided surfaces determines the tension profile of the spinning line. This physical resistance, known as dynamic drag force, depends on the viscosity of the liquid, the speed of the rove, and the physical roughness of the contact points. Measuring this force requires specialized online strain gauges placed along the path of the yarn.
Correct calibration prevents premature yarn breakage by signaling when the tension reaches critical thresholds.
Frictional Resistance
Viscous drag in the wetting trough arises from the relative movement between the fast-moving rove and the static liquid bath. As the rove speed increases, this dynamic drag force increases non-linearly, requiring adjustment of the take-up tension on the bobbin. Friction also occurs at the guide pins where the wet fibres are aligned before entering the drafting zone.
Liquid viscosity acts as a modifier. Controlling the temperature of the bath reduces the drag by lowering the viscosity of the water and dissolved gums, which is critical for high-speed automated systems where small changes in drag can cause immediate yarn failure.
Process Influence
Tension stability is essential for preventing drafting defects and uneven yarn thickness. High dynamic drag force leads to excessive draft resistance, causing the rove to slip or break during drawing operations. Minimizing this force allows for higher processing speeds and more uniform yarn diameters in the finished linen fabric.
Spinners adjust the guide geometry to maintain force levels within the safe operating window.