Finishing Machines
Finishing machines vary both in design and capacity, but the general principle is the same in all. A series of drying cans are arranged for the application of the sizing mixture. Some machines are laid out horizontally and some are upright. In the longitudinal layout the machines are more easily accessible in their different parts and under better control, while the upright machines are more compact and occupy less floor space. Fig. 3 shows a horizontal machine of the latest type. It has a drying capacity of eleven cylinders, 24 inches wide, 36 inches in diameter, allowing for a web contact of about 100 feet. These cylinders are arranged in two decks so as to economize in floor space.
The goods first pass through a pair of independently driven circular brushes, fixed at the feed end of the machine, to clear them from lint and dirt before being steamed and dried. They next pass between two pairs of nip rolls between which are fixed the steaming and sizing attachments. The goods pass through dry high pressure steam which is confined in a steam chest. They pass into and out of this chest through slots underneath the cover. A trough carries the condensed steam away from the goods and prevents dripping, otherwise they would be spotted.
Fig. 3.—Narrow Fabric Finishing Machine
The steam pressure must be carefully controlled so as to get uniform shrinkage of the goods. The steaming process softens the cotton, and the rubber threads, which are under considerable tension, gradually creep up and contract the goods. The steaming also makes the web more absorbent and thus prepares it for the size bath, through which it is passed under submerged brass rollers. The size is kept at a uniform heat by steam heated copper coils. The web then passes through the second pair of nip rolls, which are worked under pressure so as to squeeze out the size before the web reaches the drying cans.