Fig. 15.—Two views of the carding engine: upper view, cotton entering; lower view, cotton leaving.
In the main, the parts which operate upon the cotton fibres in their passage through this machine consist of a number of cylinders or rollers of various diameters, but practically equal in width. Some of these rollers are merely to guide and conduct the cotton forward, but the more important are literally bristling all over with a vast number of closely set and finely drawn steel wire teeth, whose duty it is to open, and comb out, and clean the fibers as they pass along.
To begin with, the "lap" or roll of cotton is placed behind the machine so as to rest on a roller of 6 inches in diameter, which slowly unwinds the lap at the rate of about 9 inches per minute, by frictional contact therewith.
Here, it may be said that the width of this and other chief rollers and cylindrical parts of the card may be about 38 inches or 40 inches wide, there being a tendency to make present-day Carding Engines rather narrower than formerly, in order to give greater strength to certain parts. From the lap roller the sheet of cotton is conducted for about 8 inches over a smooth feed plate, and then it goes underneath a fluted roller of 2¼ inches diameter, termed the feed roller, having practically the same surface speed as the lap roller, or possibly a small fraction more to keep the cotton lap tight.
At this stage the actual work of the Carding Engine may be said to commence. While the feed roller and the feed plate hold the end of the sheet of cotton and project it forward at the slow rate of 8 or 9 inches per minute, this projecting end of the lap becomes subject to the action of a powerful roller or beater termed the taker-in or licker-in.
The most recent and improved construction of this roller is termed the Metallic Taker-in, and it is covered all over with strong steel teeth shaped something like those of a saw. It is about 9 inches in diameter, and its strong teeth strike the cotton down from the feed roller with a surface speed of nearly 1000 feet per minute.
It is at this stage that the bulk of the heavier impurities still found in the cotton are removed, as these fall through certain grids below the taker-in immediately they are loosened from the retaining fibres by the powerful teeth of the taker-in.
The great bulk of the cotton fibres, however, are retained by the teeth of the taker-in and carried round the under side to a point where they are exposed to the action of the central and most important part of every Carding Engine, viz., the main "cylinder." The licker-in contains about twenty-eight teeth per square inch, but the "cylinder" is the first of the parts that the cotton arrives at, previously referred to as being covered with a vast number of closely set steel wire teeth.
Just to convey an idea of this point to the uninitiated reader, it may be said that it is quite common to have on the "cylinder" as many as 600 steel wire teeth in one square inch. For a cylinder 40 inches wide and 50 inches diameter, this works out to the vast number of over 3,800,000 steel wire teeth on one cylinder, each tooth being about ¼ inch long, and secured in a cloth or rubber foundation before the latter is wound round the cylinder.
The steel teeth of the cylinder strip the fibres from the taker-in and carry them in an upward direction, the surface speed of the cylinder being over 2000 feet per minute.