Impact of gin saw tooth design on fiber and textile processing quality

Authors: Hughs, Sidney; Armijo, Carlos

Submitted to: Journal of Cotton Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/16/2014
Publication Date: 4/10/2015
Publication URL: http://handle.nal.usda.gov/10113/61683
Citation: Hughs, S.E., Armijo, C.B. 2015. Impact of gin saw tooth design on fiber and textile processing quality. Journal of Cotton Science. 19:27-32.

Interpretive Summary: Toothed gin saws in saw gin stands have been used on cotton to separate the fiber from the seed (ginned) in the U.S. for over 200 years. Currently in the US, approximately 95% of the cotton ginned is processed through saw gin stands of several different manufacturers using their own saw tooth design. Most of these designs were developed by trial and error. A complete and scientific analysis of tooth design has never been done. It is not known whether the optimum saw tooth design has been found, particularly for modern upland varieties currently being grown in the US. A ginning test was done utilizing a modern saw gin and five different saws manufactured by different suppliers for the test saw gin stand. Each of the tooth designs on the five different saws was somewhat different in shape but they were all commercially manufactured for the saw gin stand used for the test. A significant difference during ginning was that the process rates through the saw gin stand varied by as much as 34% depending on the design being tested. There were also some small fiber length differences between gin saws after the ginning and lint cleaning process was completed. All of the raw ginned fiber was then processed through both open end and ring spun yarn tests. Open end yarns are generally used for coarser fabrics such as denim while ring spun yarns are generally used for higher quality clothing and related fabrics. There were very few quality effects relative to the different gin saws for the open end yarns. However, there were significant differences in the ring spun yarns due to the different gin saws. The differences included spinning efficiency, yarn evenness (an important quality measure), and yarn strength. These differences would have a significant impact on commercial textile mill productivity and profitability. These differences on higher quality yarns indicate that gin saw tooth design may significantly affect spinning efficiency and yarn quality which is an important reason to optimize gin saw tooth design. Research is continuing to further understand how gin saw tooth design affects ginned fiber quality and textile processing quality factors.

Technical Abstract: Toothed gin saws have been used to separate cotton fiber from the seed for over 200 years. There have been many saw tooth designs developed over the years. Most of these designs were developed by trial and error. A complete and scientific analysis of tooth design has never been done. It is not known whether the optimum saw tooth design has been found, particularly for modern upland varieties. Initial laboratory ginning evaluations of some modern gin saw teeth has shown differences between designs in ginning rate, raw fiber length and length uniformity measurements, and textile processing quality. The saw gin stand used for testing was a Continental Double Eagle that had been cut down to 46 saws for laboratory use. Four “different” sets of 16-inch diameter, commercially available replacement saws, were obtained from suppliers other than Continental, and along with the standard Continental saw set, were used for the five test saw sets in the ginning test. A noticeable difference between saw sets, prior to running the test, was that the number of teeth per saw varied from 328 to 352. Testing of the five gin saws was replicated 4 times resulting in a total of 20 ginning lots. Each ginning lot was then analyzed for raw fiber quality, and textile spinning performance. Most of the raw fiber HVI and AFIS properties were not significantly affected by the saw treatments. However, HVI length and length uniformity after one stage of lint cleaning were significantly different among saw treatments. An unexpected difference was that there were significant differences in seed cotton processing rate through the gin stand. The ginning rates varied by 34% from the lowest to the highest at a constant gin stand motor load. The ginned fiber was processed into both open end and ring spun yarns. There were very few significant differences among saw treatments for the open end yarn but there were several significant differences for the higher quality ring spun yarn. There were significant differences between saw treatments for the ring spun yarn in ends down (a measure of spinning efficiency), yarn evenness and yarn strength. This indicates that gin saw tooth design may significantly affect spinning efficiency and yarn quality which is an important reason to optimize gin saw tooth design. Research is currently being done to further understand how gin saw tooth design affects ginned fiber quality and textile processing quality factors.