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Engineering and ginning: Roller Ginning

Armijo, Carlos B., Whitelock, Derek P., Thomas, Joe W., Hughs, Sidney E., Gillum, Marvis N.
Journal of cotton science 2017 v.21 pp. 199-209
Gossypium hirsutum, bales, cotton gin, fiber quality, leather, lint cotton, vibration, United States
Roller ginning provided the first mechanical means of separating cotton lint from seed. The first true roller gin was the Churka gin, which was hand operated and consisted of two hard rollers that ran together at the same surface speed, pinching fiber from the seed and producing up to 2.3 kg (5.0 lb) of lint/day. In 1840, the McCarthy gin was invented to gin extra-long-staple (ELS) cotton. It consisted of a leather ginning roller, a stationary knife held tightly against the roller, and a reciprocating knife that pulled the seed from the lint as the lint was held by the roller and stationary knife. Although the ginning capacity of the McCarthy gin was a major improvement over the Churka gin, capacity was limited to about 18 kg (40 lb) of lint per hour due to machine vibration of the reciprocating knife, and associated gin stand maintenance problems. In the late 1950's and early 1960's, a rotary-knife roller gin was developed. The roller and stationary knife of this gin were similar to those of the McCarthy gin, but a rotary knife was used instead of the reciprocating knife. The rotary-knife roller gin had a considerably higher ginning rate than the McCarthy gin [218 kg (480 lb) versus 18 kg (40 lb) of lint per hour on a 1-m (40-in) wide stand], though the rotary knife gin still processed cotton at only about one-fifth the rate of a saw gin. About 2005, commercial development of a high-speed rotary-knife roller gin was accomplished. The high-speed roller gin processes cotton at about 872 kg/m/hr (576 lb/ft/hr) or about four bales per hour; this is the same rate per unit-width as a saw gin. The high-speed roller gin not only allows ELS cotton (such as Pima) to be ginned more efficiently, but also permits high-quality Upland cotton to be roller ginned at a rate more comparable with the saw gin while achieving the benefits of better fiber quality resulting from roller ginning. Although variations of the McCarthy gin are used today in many countries to gin ELS cottons, the rotary-knife roller gin is the only type of roller gin used in the U.S.