Air Jet Spun Yarn Mechanics in Elastic Woven Fabrics
Air jet core-spun yarns deliver torque-free, pill-resistant elastic wovens by locking polyurethane filaments inside parallel staple cores bound by vortex wrappers.
Wrapper Fiber Helix Angle
Structural Geometry
Orientation of the external fibres in a vortex or air-jet spun yarn defines their placement relative to the longitudinal axis of the yarn core. The wrapper fiber helix angle determines how tightly these surface fibres bind the parallel core together. This orientation is a primary factor in the final strength and pilling resistance of the yarn, which directly affects how the material performs during repeated laundry cycles.
Formation Force
Centrifugal forces and air currents within the spinning nozzle wrap the trailing ends of the fibres around the central bundle. A steeper wrapper fiber helix angle creates a more compact and durable yarn. The speed of the air flow and the geometry of the spinning tip are the main variables that control this angle during production.
Angle Verification
Analysis of the structure requires high-magnification microscopy to view the surface of the yarn. Researchers measure the wrapper fiber helix angle across multiple points to ensure uniformity throughout the lot.
Performance Relation
Yarn with a low angle tends to be softer. High angles improve the resistance to pulling and snagging in knitted applications because the surface fibres are more securely anchored. This tighter structure prevents the core from being pulled apart under high stress.