Optimizing the frequency of the rotary knife on a roller gin stand

An experiment was run to determine the optimum frequency of the rotary knif e on a roller gin stand. Six treatment levels of rotary knife frequency, 15 0, 300, 450, 600, 750, and 900 rpm, were chosen, (The manufacturer's specif ication for rotary knife frequency on the gin stand tested is 389 rpm.) The factors considered in determining the optimum rate included fiber and cott onseed quality, lint turnout bale value, and ginning rate. There were no si gnificant differences due to treatment with respect to fiber properties. Ov erall, fiber strength and elongation by the Stelometer averaged 27.8 g/tex and 6.98%, respectively; fiber span length and uniformity by the Fibrograph averaged 3.52 cm (1.38 in.) and 47.5, respectively; and fiber grade, stapl e, and micronaire by the USDA-AMS Classing office averaged 2.17, 46.8 32nd- in., and 38.1, respectively. These fiber properties are on samples taken fr om the bale and included two mill-type/air-jet lint cleaners. With the exce ption of linters content, there were no significant differences due to trea tment on the cottonseed properties. Overall, foreign matter content of the cottonseed averaged 2.16%, and cottonseed grade averaged 114. Linters conte nt ranged from 1.67 to 2.88% on the 300 and 900 rpm treatment, respectively . Lint turnout and bale value were not significantly different due to treat ment, averaging 35.3% and $438.71 overall. Ginning rate tvas significantly different due to treatment; the highest rate occurred on the 300 rpm treatm ent and was 350 kg/m/h (1.90 bales/h). Using regression analysis, the optim um rotary knife frequency occurs at 269 rpm. At rotary knife frequencies le ss than 269 rpm, some of the ginning area on the roller is wasted, and roll er damage is possible due to tags that cannot be cleared At rotary knife fr equencies greater than 269 rpm, compromises are made between ginning rate, seed cotton carryover; and choke-ups.