An alternate miniature cotton spinning system
The linking farming systems project has identified a need to test the textile performance of batches of cotton from field trials that are too small for processing via CSIRO's full-scale mill. To meet this need, CSIRO has recently re-furbished a ‘Shirley' miniature spinning plant. This equipment was first manufactured in the mid 1950s by the Shirley Institute in England and was originally designed for and employed by commercial mills and research organisations for processing small batches (less than 1kg) of fibre to determine spin ability. With the advent of high volume instruments (HVI), such practices were made redundant and thus the production of such small-scale spinning apparatus had been discontinued by the 1980s.
The Shirley miniature spinning plant consists of a small card, draw-frame and ring spinning frame. Since no opening or pre-card cleaning is possible on the miniature system, the manufacturer's recommendations are to card the material twice. Following carding, three miniature draw passages are recommended to draw out the sliver until it is light enough to be spun directly on the miniature spinner. Un-like full-scale spinning, this miniature system does not include the crucial intermediate step of producing a twisted roving between drawing and ring-spinning.
CSIRO found that inferior and practically un-processable yarns were produced when using the recommended miniature system; numerous breaks occurred during processing, with slubbing (thick places) prone weak yarns being produced. This occurred because of the large amounts of draft and twist that were applied to the un-twisted sliver on the ring-spinning machine.
An alternate miniature spinning protocol was devised using a combination of both miniature and full-scale equipment, while still maintaining the small sample size. The main difference between the traditional and alternate miniature spinning protocol, is that the alternate process has an additional step of creating a twisted roving between drawing and spinning, and only relies on two draw frame passages. In addition, full-scale machinery is used for the second draw passage, the creation of twisted roving and ring spinning, which is more in-line with a commercial spinning situation. The experimental sample required for this protocol is small, being only 170g.
To facilitate a comparison between the two spinning methods, 20 tex yarns were manufactured using an industry standard variety. Studies for two years have shown that there was no significant difference between commercial full-scale and the new alternate miniature spinning system for processing performance, and yarn evenness and strength
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