Quantitative Impact of Short Fiber Content on Combed Cotton Rotor Yarn Tenacity Limits
Combing cotton sliver below 5.5% short fiber content raises rotor yarn tenacity ceilings to 18.5 cN/tex by reducing friction slip inside the rotor groove.
Uster CVm
Variation Index
Statistical index representing the coefficient of variation in yarn mass provides a numerical value for the unevenness of a textile strand. Capacitance testing equipment measures the mass per unit length as the yarn passes through a sensor. A higher uster cvm indicates a less uniform product that may cause visual defects in the finished fabric.
Capacitance Test
Measurement procedure involves feeding the yarn through the testing head at speeds of up to eight hundred meters per minute. The sensor records the fluctuations in mass and calculates the standard deviation relative to the mean. This data allows the spinning mill to identify mechanical issues in the drafting rollers or the fiber preparation machinery.
Product Grading
Commercial value of the yarn is often determined by its standing on the global benchmark charts provided by the equipment manufacturer. A low percentage value indicates a high quality yarn that will perform well in demanding applications. Fabrics made from yarn with a low uster cvm show a smooth, clear surface with no cloudy or streaky patterns.
Testing Cut
Accuracy of the result is affected by the speed of the yarn and the length of the sample being tested. Standard practice requires testing at least one thousand meters per package to ensure the statistical significance of the data. Any change in the moisture content of the yarn will alter its dielectric property and may affect the mass reading.