Uniformity Statistic
The coefficient of mass variation measured over a running length of yarn, roving, or sliver represents the primary global standard for expressing textile mass irregularity. The uster CV percent represents the standard deviation of mass per unit length divided by the mean mass, expressed as a percentage value. It is the core metric used to evaluate yarn quality in commercial contracts, providing a clear benchmark that determines the market value of spun yarns.
Measurement Process
Continuous capacitive testing of yarn running through a slot measures changes in electrical capacitance which correspond to yarn mass variations. A higher uster CV percent indicates a more irregular yarn with a greater number of thin and thick regions. This value is compared against global reference benches to grade yarn quality.
Processing Diagnostics
Spinning mills analyze the frequency patterns within this irregularity measurement to locate the source of drafting defects in the draw frame or ring frame. Reducing the uster CV percent is achieved by adjusting roller pressure, fiber blending, and drafting speed. This reduces the risk of yarn breakage during subsequent knitting or weaving.
Fabric Quality
High variation percentages produce an uneven fabric surface that deteriorates the appearance of dyed garments. The uster CV percent is a predictor of finished fabric hand and dye consistency. This statistic is monitored to prevent expensive fabric downgrades.
