It will be 218 years ago this month on March 14, 1794, that Eli Whitney patented a spike tooth gin stand. Long before Whitney’s patent, all cotton was ginned in America on little roller-type gins that looked like they came off wringer washing machines. Among other things, these little gins were called churkhas. Two years later, in 1796, Hogden Holmes patented a gin stand that actually used saws that came to be combined with Whitney’s deal to eventually become the saw gins that are predominately used today.
However, roller-type gins did not completely die out in America but have continued to be used primarily on Sea Island or Pima-type cottons up until the present time. These early roller gins later evolved into the reciprocating-knife roller gin in the 1840s and the rotary-knife roller gin in the 1960s.
When the 2011 ginning season finally ends in late March or early April, some one million bales (80 percent Pima and 20 percent upland) of U.S. cotton will have been roller ginned out here in the West. Historically, in the West, there has always been a niche for roller ginning of the longer staple upland varieties for special purposes. With the recent development of high-speed roller ginning, there has been a significant increase in the amount of roller ginned upland such that approximately 200,000 roller ginned upland bales will have been produced by the end of the 2011 ginning season.
There is an economic reason for the roller ginning increase in that 1) high-speed roller gins are more competitive with saw gins in their ginning production rates and 2) there is a significant increase in upland fiber length and uniformity that has brought a premium in the marketplace. The long staple upland cottons grown in the Far West have responded well to roller ginning and have resulted in real economic gain for producers. The economic gain is evidenced by the sustained and growing practice of roller ginning western uplands over the past several years.
Interest in the economic incentive from high-speed roller ginning of upland cotton has been spreading east to cotton- growing areas of Texas and beyond, which would not have even considered roller ginning in the recent past. This increased interest brings me to the point of this article. There has always been a small pool of experienced roller ginners in the Far West who, by sharing or transferring their knowledge to new installations and to saw ginners new to roller ginning, made it relatively straightforward to ramp up roller ginning of upland cotton in this region.
However, as one longtime saw ginner who was in his third season of roller ginning upland cotton and starting to get the hang of it said, “Roller gins are not at all like saw gins – you adjust them differently and you operate them differently – you set up a saw gin at the beginning of the season and just let it gin, but you watch and adjust roller gins all during the ginning season.”
Another said, “Roller gins do not like damp cotton – saw gins don’t like it either, but they are more tolerant.”
So if you are a producer, ginner or gin manager from a traditional saw-ginned upland area who is thinking of getting into roller ginning, you must expect to make some changes in your thinking about running a cotton gin. There are a growing number of ginners who can now operate both saw and roller gins, but an experienced saw ginner cannot be expected to operate a roller gin successfully without significant additional training and experience.
Some of this training can be had right away at the annual Western Gin School (May 8-10, 2012), which covers both saw and roller ginning methods and principles. Machinery manufacturers and other experienced ginners are also good sources of roller gin operational knowledge. Drying capacity is a second major concern. If you are thinking of making a saw gin plant into a combo saw and roller gin plant, you may have to increase your drying capacity.
The frictional principle that roller gins operate on to separate the fiber and seed successfully requires seed cotton to be drier than is required for saw gins. Bottom line is that the fiber length and uniformity advantages of roller ginning upland cottons are real.
Ed Hughs is Director of the Southwest Ginning Research Laboratory in Mesilla Park, N.M. Contact him at (575) 526-6381 or firstname.lastname@example.org.