Modern Dyeing Machinery and Equipment in Dyeing Process

Modern dyeing machines are made from stainless steels. Steels containing up to 4% molybdenum are favored to withstand the acid conditions that are common. 

A dyeing machine consists essentially of a vessel to contain the dye liquor, provided with equipment for heating, cooling and circulating the liquor into and around the goods to be dyed or moving the goods through the dye liquor. The kind of machine employed depends on the nature of the goods to be dyed. Labor and energy costs are high in relation to total dyeing costs: the dyers aim is to shorten dyeing times to save steam and electrical power and to avoid spoilage of goods. 

The conical-pan loose-stock machine is a widely used machine. Fibers are held in an inner truncated conical vessel while the hot dye liquor is mechanically pumped through. The fiber mass tends to become compressed in the upper narrow half of the cone, assisting efficient circulation. Leveling problems are less important as uniformity may be achieved by blending the dyed fibers prior to spinning. 

The Hussong machine is the traditional apparatus. It has a long, square-ended tank as a dye bath into which a framework of poles carrying hanks can be lowered. The dye liquor is circulated by an impeller and moves through a perforated false bottom that also houses the open steam pipe for heating. In modern machines, circulation is improved at the points of contact between hank and pole. This leads to better leveling and elimination of irregularities caused by uneven cooling. In package-dyeing machines dye color may be pumped in rather two directions: 

• Through the perforated central spindle and outward through the package or 
• By the reverse path into the outer layers of the package and out of the spindle. In either case levelness is important. 

Some package-dyeing machines are capable of working under pressure at temperatures up to 130C. 

The winch is the oldest piece of dyeing machine and takes its name from the slated roller that moves an endless rope of cloth or endless belt of cloth at full width through the dye liquor. Pressurized-winch machines have been developed in the U.S. 

In an entirely new concept, the Gaston County jet machine circulates fabric in rope form through a pipe by means of a high-pressure jet of dye color. The jet machine is increasingly important in high-temperature dyeing of synthetic fibers, especially polyester fabrics. Another machine is the jig. It has a V-shaped trough holding the dye color and guide rollers to carry the cloth at full width between two external, powered rollers, the cloth is wound onto each roller alternately, that is, the cloth is first moved forward, then backward through the dye color until dyeing is complete. Modern machines, automatically controlled and programmed, can be built to work under pressure.