Determining Residual Torsional Energy Limits in Plied versus Alternate Feed Single Jersey Knits
Plied yarns neutralize torsional spirality within the strand cross-section, while alternate feeds distribute opposed stresses across alternating courses.
S-Twist
Helical Orientation
A yarn twist direction produces spirals that run upward from right to left, matching the central section of the letter S. In textile spinning, the s-twist orientation is achieved by rotating the spindle or rotor in a counter-clockwise direction. This twisting holds the loose staple fibres together, giving the yarn its strength, elasticity, and cohesion. Spun yarns are specified with this twist direction to ensure compatibility in subsequent weaving or knitting operations, where balancing twist directions is essential to control fabric bias and maintain the structural integrity of the finished knit or woven panel.
Yarn Plying
Combining multiple single yarns requires reversing the twist direction to prevent unravelling and snarling. When single s-twist yarns are plied together, they are typically twisted in the opposite z-twist direction to balance the internal forces. This opposing twist locks the strands in place, creating a stable, balanced ply yarn.
The choice of twist combination directly affects the yarn density and hairiness.
Fabric Structure
Alternating both twist directions in the same weave produces unique surface textures and reduces distortion. Weavers arrange s-twist and z-twist yarns in alternating patterns to neutralize fabric torque and prevent skewing. This alternating order creates a balanced fabric that lies flat and holds its shape after laundering.
It also enhances the drape and visual texture of crepe and georgette fabrics.
Production Balance
Spinning machinery must be configured correctly to maintain the chosen direction. Technicians inspect the drive belts and spindle rotation to ensure that s-twist is produced consistently across all stations. Any mixture of twist directions in the same yarn batch will lead to uneven dyeing and knitting defects.
This control is necessary to guarantee uniform batch quality.