Design, construction and testing of a cotton gin.

Test results showed that the ginning rib significantly affected the machine's ginning capacity, ginning recovery and ginning efficiency as well as the quality of the cottonseeds produced. The pitch angle of the saw teeth significantly affected the machine's ginning efficiency and the quality of the fibers and cottonseeds produced. On the other hand the saw speed significantly affected all the dependent variables except the fiber strength. Considering the different combinations of the independent variables tested, the optimal operating conditions of the designed machine as determined using the the Response Surface Methodology (RSM), was a teeth pitch angle of -60 degrees combined with the second rib design (RD-2) and a saw speed of 160 RPM. Limits for the saw speeds and teeth pitch angles within the machine's optimal operating condition were defined. At optimal operating condition, the designed machine's ginning capacity, ginning recovery and ginning efficiency were 0.54 kg seed cotton/hr/saw, 39.9% and 99.96%, respectively. The average length, uniformity ratio and strength of the fibers (UPL-C2 variety) were 27.13 mm (medium-long staple), 46.74% (high) and 19.14 g/tex (average strength), respectively. On the other hand, the average fuzz content and the amount of damaged cottonseeds were 11.21% and 2.03%, respectively. The designed cotton gin gave a significantly higher ginning recovery and lesser amount of injured cottonseeds compared with existing saw-gins. On the other hand, its ginning recovery was comparable with and its amount of injured seeds relatively higher than the existing roller gins. The three ginning machines (designed, saw and roller gins) performed comparably in terms of the other parameters such as ginning efficiency, fiber length, fiber strength, uniformity ratio and cottonseed fuzz content.