Cotton-Finishing Machinery

COTTON-FINISHING MACHINERY Only a relatively small quantity of woven cotton-cloth is sold to the actual user in the condition in which it leaves the weaving shed ; i.e., in "loom-state." Much of it is bleached, dyed or printed in the piece, and subsequently passes through a number of finishing processes. Even coloured goods woven from dyed yarns, or cloths in the "grey" state are usually submitted to treatment for the purpose of straightening, smoothing, stiffening, glazing, raising or in some way changing the appearance and feel of the cloth. For this purpose a very large number of mechanical devices are em ployed ; and by these, cotton cloth can be stretched, pressed lightly or heavily, subjected to friction by contact with rough or smooth surfaces, ironed by contact with hot smooth metal sur faces, impregnated or covered with stiffening and weighting solu tions and pastes, and dried under different conditions by heated surfaces or by hot air. Indeed, the whole nature of the cotton may be altered by the application of strong chemicals in suitably con structed mechanical apparatus.

The finishes obtained by these means are numberless in degree and kind, and do not readily fall into distinct categories ; and identical or nearly identical effects may be obtained in different works by considerable variations in plant and method. It is, how ever, possible, by having regard to the more usual functions of the machines, to divide the latter in a number of different classes.

Mangling.

Cloth which has reached the final stage of the bleaching or other wet process is of ten in the rope form ; i.e., the cloth is twisted along its length for convenience of handling in the various treatments of boiling, "chemicking," souring and so on. As a necessary preliminary to further operations, say, of dry ing or starching, it is opened out by the scutcher, in which the twists in the cloth are partly beaten out (left- and right-hand twists neutralizing each other) and partly drawn open by rollers supplied with raised scrolls which engage the cloth as it passes over ; the cloth is thus delivered in the open width.

In this condition it may be passed through a water mangle, with several objects in view. First, a final washing; secondly, a straight ening, partial at least, of the weft threads, removing the distortion suffered in previous treatment ; thirdly, some recovery in the ac tual width of the cloth. The water mangle is largely used at this stage in the preparation of white goods for closing the threads of the cloth and preparing it to receive a subsequent filling. Essen tially, the water mangle consists usually of three or more heavy rollers so arranged that the cloth emerging from a water trough may be passed between them under very great pressure.

Drying.

Af ter mangling, the goods are often dried before passing on to the filling or stiffening process. This operation is conveniently carried out by passing the cloth over a series of copper cylinders heated by steam, and arranged in a horizontal or vertical plane. Or drying may, under other conditions, be effected by blowing hot air on to the cloth held out between parallel travelling chains supported by a long metal frame—the stenter.

Stiffening.

The process of starching is usually performed in starch mangles, resembling the water mangles already referred to. In the simplest form, two wooden bowls or rollers, the lower run ning in a box containing the starch paste, are arranged so that the cloth passing through the nip of the rollers under pressure is evenly impregnated with the starch. In other modifications the starch may be applied to one side of the cloth only, whilst in yet another style the bowls revolve at different speeds, so that a friction effect is produced on the cloth charged with the filling.

Calendering.

With the object of imparting a desired lustre, feel or compactness to the cloth, use is made of the calenders. These machines are constructed of metal, and paper or cotton bowls, which can be maintained under pressure and which may rotate at the same or different speeds. The metal bowls are usu ally heated by gas or steam, and are therefore made hollow. The number of bowls ranges from three to ten or more. The Schreiner calender is a particular form in which the cotton fabric is sub jected to the action under very great pressure of a steel roller en graved with a large number (25o or more) of parallel lines to the inch, and thus acquires a very high lustre, especially if the fabric be first mercerized.

A bright linen-like finish is produced on cotton goods of cer tain kinds by the device known as the beetle. The cloth, rolled on a beam, is submitted to the hammering action of wooden fallers. These fallers are lifted by cams, and allowed to drop one after the other to the number of, say, 4o in a single machine, the ham mering being continued for from a half-hour to several hours.

(F. Sc.)