Draft Allocation and Tensor Setting in a Sliver-to-Yarn Drafting System for Cotton

Abstract

This work investigates the effect of draft allocation on yarn properties in a sliver-to varn drafting system consisting of a back draft zone, an intermediate condensing zone, and a final draft zone. Back and front zones were of the double apron type. The effect of a range of pin openings for the front apron nip was also investigated.

Results showed that for optimum yarn properties, back draft D ₁ and total draft D should be related to each other so that D ₁ = K √D, where K is a parameter dependent on drafting efficiency and is close to unity. Optimum yarn properties were obtained with the smallest available tensor in the front zone. Finally, in an attempt to explain results on the basis of previous theoretical work by other writers, it was shown that for ideal conditions D ₁ = √D.