Calendering is a mechanical finishing process typically used to produce special effects in fabric, such as high luster, smoothness, or even embossing. In this operation, primarily used on woven goods, the fabric is passed between heated rolls under heavy pressure to flatten the fabric. Usually a three-roll process, a central cotton fabric or paper roll is sandwiched between two metal heated rolls rotating at faster speeds.
For friction calendaring, the cloth is unwound from a fabric supply roll. Steam is applied before it moves around the calendaring rolls which apply pressure, hundreds of pounds per square inch. As a result, this fabric is brought to a highly polished state. Schreiner calendaring is a specialized system. In this scenario two rolls are used, a small roll and a larger, finely engraved roll. This large, heavy metal roll is engraved at a 36-degree angle with fine, or shallow, lines. The number of lines can range from 180 to 500 per inch but are most often 300 lines per inch. Heat is maintained as the fabric is guided under pressure between the engraved roll and a smaller, steel roll which is heated. The Schreiner roll has a greater surface feed than does the small steel roll. Notice the difference between fiber structure before and after it has been calendered. This flattened form allows more surface for light to be directed back to the viewer resulting in more luster. Because of this, fabric finished by the Schreiner calendar method appears to have a lot more luster. It is also less flexible because calendaring flattens the fiber and reduces the permeability With embossing, another calendaring method, a pattern is embedded into the fabric. An embossing calendar consists of an upper engraved steel roll and a lower composition or paper roll with a negative pattern of the metal roll. As the fabric moves between these rolls, embossing occurs. Thermoplastic fiber can be set by heat while cellulosic fibers must have a resin finish applied to ensure a durable effect. This kind of calendaring produces many popular fabrics such as fake seersucker, crepes, and other relief fabrics.
0 yorum:
Yorum Gönder
Merhaba, daha kaliteli bir site için yorumlarınızı bekliyoruz.