Delivery Mechanism
Driven yarn metering devices actively deliver precise lengths of yarn to knitting needles at a constant speed synchronized with machine rotation. Knitting mills install positive yarn feeder units on circular knitting machines to eliminate tension variations caused by yarn package unwinding resistance or friction along yarn pathways. Active yarn delivery ensures perfectly uniform loop size across all knitting feeds on the cylinder.
Operational Dynamics
Unlike passive tensioners that rely on needle pull to unwind yarn, driven storage wheels turn at a rate directly geared to the machine drive. Operating a positive yarn feeder ensures that every needle receives an identical length of yarn per revolutions, establishing precise control over stitch length and fabric weight. A drive belt connected to the machine main shaft turns the feeder wheel, pulling yarn from the creel and storing several wraps on a rotating drum.
Photocell or mechanical sensors monitor yarn presence, stopping the machine instantly if a yarn breaks upstream. Eliminating tension fluctuations prevents horizontal banding, striping and density variations across the circular fabric tube. Advanced electronic positive feeders allow computer-controlled tape speed adjustments for quick changes in fabric weight and loop length settings.
Stitch Control
Consistent stitch length control stabilizes fabric width and prevents fabric spirality caused by uneven loop tension across adjacent courses. Integrating positive yarn feeder technology dramatically reduces fabric weight variations across long production runs. Uniform loop formation improves fabric stability and reduces stress on knitting needles during high-speed operation.
Defect Elimination
Passive yarn delivery systems suffer from package unwinding tension spikes that generate visible horizontal bar defects in sensitive filament fabrics. Utilizing positive yarn feeder systems eliminates yarn drag variations, maintaining smooth loop geometry across fine gauge circular knitting machinery. Quality improvement lowers fabric rejection rates at final inspection.
