Measurement of Sliver Drafting Forces

Abstract

A staple draftometer is described using a "Hall Effect" wattmeter as the transducer for measuring dynamic forces in staple slivers during drafting. The procedure for calibration and use of the instrument is also given. A novel feature of the apparatus is the use of a decade resistance box to calibrate the desired full-scale force range. Drafting force was a hyperbolic function of draft ratio (beyond 1.5× draft), and the relationship between the two variables can be expressed in terms of a constant as shown by the following equation: (Drafting Force) X (Draft Ratio) = K Thus the drafting force curve in terms of draft ratios can be defined by a single numher. An increase in crimp frequency (0-15 crimps per inch range) gave an exponential increase in sliver drafting force. Addition of luhricants such as Ucon® or silicone oils to clean T-54 Dacron® polyester fiber slivers produced a significant reduction in drafting force, most of which occurred during the addition of the first 0.1% lubricant. The absolute drafting force is governed by specific properties of the lubricant.