Spindle Drafting of Woolen Slubbings

Abstract

An apparatus incorporating a single mule spindle was designed to draft woolen slub bings under a variety of conditions of twist and speed, and to measure the drafting forces generated. Experiments were done on this apparatus and on the mule itself. The way in which drafting force is generated was investigated for Cheviot and Saxony slubbings with varying speed, count, and twist. The way in which the thread irregularity changed during drafting was investigated simultaneously. It was found that force first increased with extension and then decreased. During this second stage of decreasing force, evidence was sometimes found of the spasmodic slipping and sticking of fibers. Levelness of thread improved while drafting force was increasing, but deteri orated rapidly as the force declined. This indicates that optimum draft might be deter mined by force measurements. The angle of inclination of the spindle was also found to affect the magnitude of the drafting force. A two-phase hypothesis of fiber behavior has been advanced, in which it is suggested that fiber response during the first phase consists mainly of straightening and stretching. This is superseded by a second phase which is characterized by fiber slippage, often of a violent nature. It is suggested not only that this does provide a new standpoint from which the process of spindle drafting can be considered, but also that development of the experi mental technique might provide ready means of investigating the importance of various fiber properties, and their modification, in the spinning process.