Proposals towards improving worsted processing. Part 1: identification and theoretical evaluation of possibilities for optimising the drawing sequence

Abstract

The possibility of improving the evenness of worsted slivers, rovings and yarns by the simple expedient of optimising the drawing sequence is examined theoretically. The drawing sequences commonly used by mills have generally been established by trial-and-error methods, using the knowledge that the evenness of any material can be contained or improved by the practice of doubling, and made worse by drafting, but with little or no application of scientific method. A simple mathematical model of the worsted processing sequence, which has proved to be a powerful tool for both problem solving and in research, is used to investigate if and how yarn quality might be improved by simple adjustments to the number of doublings and the draft ratios used. The outcome of these theoretical studies predicts that some improvement in the quality (evenness) of yarn can be achieved, and raises questions about the appropriateness of the doublings and the draft ratios commonly used.

Keywords:

• worsted processing
• modelling
• optimisation
• effects of doubling and drafting