Uster analysis of cotton/polyester blended spun yarns with different counts

Textile engineers in ring spinning1 industries are fully dependent on uster yarn evenness tester2 to decide yarn qualities as per customer expectations of unevenness, coefficient of variation of mass and hairiness of spun yarn. The Uster yarn evenness tester is the instrument developed by Switzerland Uster Company, and it is used to test the evenness of yarns. This evenness tester uses the capacitance conversion principle3 to translate the non-electric yarn section change into the electric singles representing the change of section. The testing part is composed by the capacitors with two parallel metal plates. Because the dielectric coefficient of the fiber materials exceeds the dielectric coefficient of air, when the sample of yarn enters into the capacitor with certain speed, the capacitance of the polar plate will increase, and the change of the capacitance is related with the actual volume of the yarns in the polar plates (Figure 1).4