Rotational Force
Mechanical twisting energy imparted to staple fibres or continuous filaments during yarn spinning creates internal torsional tension within single yarns. In textile manufacturing, torque measures the rotational tendency of a yarn to untwist or snarl when relaxed. Unbalanced rotational force causes single jersey knitted fabrics to spiralate, displacing side seams in finished garments after laundering.
Textile engineers balance S and Z twist insertion rates to minimize internal residual forces in balanced ring-spun yarns.
Yarn Twist
Ring spinning frames insert torsional force to lock individual fibres together into continuous strands. High levels of yarn torque increase tensile strength but simultaneously elevate snarling tendencies during knitting or weaving operations. Yarn steaming and heat setting processes soften polymer chains, relieving frozen internal stresses before fabric formation.
Plying two single yarns with opposing twist directions cancels residual torsional forces, producing balanced plied structure.
Fabric Distortion
Unrelieved torsional energy inside knitted loops forces loop columns to lean at an angle relative to the fabric edge. Excessive yarn torque produces severe garment bias, causing side seams to twist around body torsos after household washing cycles. Dyeing and finishing mills apply mechanical tentering frames to temporarily straighten skewed knits, but residual energy recovers during laundering.
Mechanical Equilibrium
Zero net rotational force occurs when opposing physical forces inside the yarn structure achieve complete static balance. Measuring torque levels before knitting prevents costly fabric spirality defects, establishing acceptable torsional limits for commercial single yarns.
