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ARS Home » Plains Area » Las Cruces, New Mexico » Cotton Ginning Research » Research » Publications at this Location » Publication #138625


item Armijo, Carlos

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/1/2004
Publication Date: 1/1/2004
Citation: Armijo, C.B., Gillum, M.N., Van Doorn, D.W. 2004. Varying the number of blades on the roller-gin rotary knife. Applied Engineering in Agriculture. 20(4):399-405.

Interpretive Summary: The rotary knife, stationary knife, and ginning roller on a roller gin stand all contribute to the actual separation of fiber and cottonseed. To prevent damaging the fiber during the ginning process, it is critical that the knives and ginning roller operate at their optimum. The objective of the research was to determine the optimum number of blades and frequency of the rotary knife. Taking into account fiber quality, cottonseed quality, carryover, and ginning rate, an experiment determined that it is acceptable to use a 3-, 4-, or 6-blade rotary knife. The 2-blade rotary knife has unacceptable levels of carryover. The optimum frequency of the rotary knife is 36 stroke/s. This frequency represents a compromise between foreign matter content in the lint and cottonseed, cottonseed linters content, and ginning rate. The research findings improve the efficiency of the roller gin stand, making the fiber more desirable for spinning. Providing a superior fiber to the textile industry benefits both the cotton producer, in higher demand for his product, and the consumer, by providing a quality fabric.

Technical Abstract: An experiment was run to determine the optimum number of blades and frequency of the rotary knife on a roller gin stand. The knife designs tested included a 2-, 3-, 4-, and 6-blade rotary knife. Each knife design was run at a knife frequency of 14.5, 18.2, 24.2, 36.3, and 72.8 stroke/s. The criteria used for determining the optimum knife design included any damage to the seed or fiber, and differences in carryover and ginning rate. With respect to cottonseed properties, foreign matter content in the seed decreased as knife frequency increased, and seed linters content was highest at the highest knife frequency. With respect to fiber properties, foreign matter content in the lint decreased as the number of blades increased, and increased as the knife frequency increased. Fiber properties such as length, strength, uniformity, short fiber, and nep content were not compromised by either rotary knife design or frequency. Ginning rate was highest at a knife frequency of 36.3 stroke/s. The recommended running frequency for the rotary knife is 36 stroke/s, and ginning with either a 3-, 4-, or 6-blade design is acceptable.