Comparative study of soft drafting system and the conventional drafting system based on the ring spinning frame

A modified drafting system, named the soft drafting system, based on the ring spinning frame, has been introduced in the previous paper. In order to compare with the conventional drafting system, this paper analyzed pressure distributions of the two drafting systems and compared apron slippages based on the condition of spinning 18.2 tex combed cotton yarns. The results show that the floating area of the soft drafting system is only 6 mm, much smaller than that of the conventional drafting system at 12 mm. In addition, the soft drafting system can provide a longer and more stable friction zone and the curved channel is more conducive to the separation of fiber bundles to reduce yarn imperfections. The soft drafting system does not have the problem of apron-to-apron slippage that may cause deterioration of yarn quality. The slip rate of the soft drafting system between the lattice apron and the middle bottom roller is 0.03%, while the slip rate of the conventional drafting system between the bottom apron and the middle bottom roller is 8.58%, resulting in a reduction in drafting efficiency and poor stability of yarn quality. The experimental results show that the soft drafting system can significantly improve yarn evenness with CVm% of the soft drafting system decreasing 10.2% over the conventional drafting system. Also, the soft drafting system can reduce yarn imperfections, especially thick places with +35% thick places decreasing 71.9% and +50% thick places decreasing 70.4%.