Effect of yarn draw-off angle on the yarn properties in friction spinning

The angle of yarn withdrawal direction when the yarn was being drawn off from the yarn-forming zone was varied and yarns were then produced at various friction roller speeds. The yarn tension in the yarn-forming zone and the yarn diameter were determined simultaneously during the spinning process. The optimum draw-off angle was explored for various friction roller speeds by considering the tensile properties and irregularity of the linear density of the yarns. We considered the optimum draw-off angle to produce a yarn at higher efficiency and lower energy consumption. The results of this research show that the yarn tension increased as the negative draw-off angle was increased. Consequently, twist efficiency increased at negative draw-off angles. Hence, it was demonstrated that a yarn of acceptable properties could be produced at lower friction roller speeds with a properly adjusted draw-off angle. The optimum draw-off angles were explored to determine where the desired twist and strength of yarn could be obtained with lower friction roller speeds. It was concluded that a small negative draw-off angle of 0 to -11 degrees was the optimum draw-off angle for various friction roller speeds, at which a yarn having the same strength in comparison with that produced in the straight direction can be produced at about 50% of friction roller rotation.