Optimization of process variables in rotor spinning for the production of cotton/milkweed blended yarns

Cotton/milkweed (60/40) blended yarn of 29.5 tex has been produced on rotor spinning system. The influence of fibre friction, opening roller speed and sliver linear density on rotor yarn properties has been studied using Box and Behnken factorial design and the optimum conditions within the processing limits of the machines are established. The results show that fibre friction is the dominant factor in determining the tensile properties and other properties of rotor-spun yarn. It is observed that a higher fibre friction gives higher yarn tenacity, and lower yarn unevenness, imperfection and hairiness. The opening roller speed also has a greater influence on rotor yarn properties. With an increase in opening roller speed, the number of points per fibre increases, which results in better fibre separation and improvement in yarn properties. But very high opening roller speed deteriorates the yarn properties and increases the end breakage rate mainly due to fibre breakage and low fibre straightness. Generally, heavier sliver weight leads to higher spinning draft which deteriorates the yarn properties.