The Effect of Cap-Edge Friction on Spinning

Abstract

Calculations of the effect of various spinning conditions on yarn tension and balloon size and shape were described in an earlier paper [1]. Here they are extended to include the influence of the coefficient of friction (μ) at the cap edge. Tension is found to increase as μ is increased and there is an upper limit to μ at which tension becomes theoretically infinite. There is also a lower limit to the value of μ below which balloons can only exist if they rub the side of the cap. For a given μ there is a limiting balloon height above which no free balloon is possible and this limiting height increases as μ increases. Tension can increase, decrease, or remain roughly constant as the bobbin diameter increases, depending on μ and the size of the bobbin. For a given coefficient of friction there is a bobbin size for which tension is infinite and an upper limit to the bobbin diameter above which free balloons cannot exist. The effect of friction on balloon size and shape is also in dicated. The radius of the cap edge is shown to influence tension indirectly through the depend ence of the coefficient of friction on the normal reaction.