Patterned Irregularity
Cyclical thickness variation describes the recurrence of mass anomalies at regular intervals along the length of a spun yarn. This fault, identified as yarn count periodicity, is caused by mechanical defects in the spinning or drawing machinery, such as eccentric rollers or damaged gears. The presence of these regular waves undermines the visual uniformity of the finished woven fabric.
Diagnostic Step
Pinpointing the mechanical source of these periodic mass changes requires running the yarn through a capacitance tester to generate a spectrogram. The spectrogram shows peaks at specific wavelengths that correspond to the circumference of particular rollers or the rotation speeds of specific gears. For example, a peak at sixty millimeters might indicate a worn rubber apron or a bent spindle on the ring frame.
Technicians use these diagnostic findings to replace the faulty components before the batch is finished, preventing large-scale production of defective linen yarn.
Weft Barring
Periodic defects are problematic when the yarn is used in the weft of high-density fabrics. These regular thick spots line up across the fabric width during weaving, creating a visual defect known as barring or diamond patterns. Such visual issues make the linen fabric unsellable for high-end clothing.
