Twist Variation Fault Diagnosis
topic
Twist variation diagnosis: (1) Measure twist at 20 spindle positions and calculate CVtwist%. If CVtwist% >5%: (2) Check tangential belt tension and condition — a worn belt causes spindle speed variation up to ±3%. (3) Check individual whorl diameters — measure all whorls; variation >0.1 mm causes proportional twist variation. (4) Check spindle speed with stroboscope at multiple positions. (5) For within-bobbin twist variation: check ring rail speed ratio (up/down stroke timing); excessive speed variation changes instantaneous delivery/twist ratio.
Role
Twist variation fault diagnosis requires integration of mechanical measurement (belt tension, whorl diameter) with yarn testing (twist per metre), a multi-disciplinary approach that is rarely mastered without specific training. Unresolved twist variation causes fabric barre that is only seen after dyeing — at which point the cost of the fault (customer rejection of finished fabric) is 50–100× the cost of the yarn. Early diagnosis before the yarn reaches the customer has enormous commercial value.