Variation Coefficient
Numerical value representing the percentage of variation in the weight per unit length of a yarn provides a standardized measure of its evenness. The uster mass cv is calculated by dividing the standard deviation of the mass fluctuations by the mean mass of the sample. Lower values indicate a more uniform thread that will perform better in subsequent weaving and knitting processes.
Measurement Technique
Capacitance sensors in the testing instrument detect changes in the yarn mass as it passes through a measuring slot at high speed. As the yarn moves, the uster mass cv is recorded alongside other data such as the frequency of thick places, thin places, neps and slubs. This statistical profile allows the mill to compare its current production against global benchmarks for linen quality.
The data is often used to adjust the settings on the drawing and spinning frames to correct systematic errors.
Fabric Appearance
High levels of mass fluctuation lead to a streaky or cloudy appearance in the finished fabric. When the uster mass cv is kept within tight limits, the resulting linen cloth shows the smooth and consistent surface that premium markets demand. This metric is the primary tool for verifying that the yarn meets the contractual specifications of the weaver.
