Short staple spinning
"Well carded is half spun."
The revolving flat card is called the heart of the spinning mill. This illustrates the immense significance of carding to the end result and the quality of the yarn.
The concept of carding has existed since 1770, and revolving top cards since 1850. Basically, these cards contained similar elements that still can be found today on high production cards: licker-in, cylinder, revolving tops, stationary flats and doffer. Each element takes an important function in carding.
Groz-Beckert supplies high quality card clothing for different types of cards and areas of application. The selection encompasses metallic card clothing for feed roller, licker-in, cylinder, doffer and stripping rollers. The product range is complemented by revolving tops, stationary flats, stationary flat systems and cleaning fillets.
Feed roller wires
This wire is responsible for uniform feeding of fibers into the card. Coarse interlocked wire is usually used to control thick fiber mats.
The licker-in's task is to open the fiber tufts and prepare them for the carding process.
The extent to which the fiber tufts are opened has a direct effect on the service life of the card clothing – the better the opening degree, the longer the service life.
Parallel to the opening of fiber tufts, trash is eliminated at the same time. Different licker-in wires are used depending on fiber type and fiber denier. There are revolving flat cards with one licker-in and cards with three licker-ins.
Together with the revolving flats and stationary carding elements in the pre and post carding zone, the cylinder is responsible for main carding action and fiber separation.
The cylinder wire selection is crucial to the intensity of the carding, in addition to cylinder rotation and flats speed. Parameters such as front angle, PPSI (points per square inch) and the height of the cylinder wire play an important role.
The doffer wire takes over the fibers from the cylinder. A high rate of fiber transfer should be reached in addition to gentle and uniform web transfer.
The tooth shape of curved doffers, used for specific doffer wires, improves fiber transfer from cylinder to doffer and facilitates transfer of the web from the doffer to the stripping roller. Doffer wires with striations increase fiber cohesion, which is very important to the processing of synthetic fiber at high production speeds.
In recent years the production of synthetic man-made fibers, a trend leading to finer fibers, has accelerated. Groz-Beckert supports this trend with the high-performance doffer wire D40-30-52C CBF. The special geometry and high tooth density (520 PPSI) result in significantly better yarn quality with regard to yarn imperfections.
Stripping roller wires
The stripping wire strips the web from the doffer wire. Web transfer should be gentle without forming thick places. Only then uniform yarn can be produced.
Revolving tops consists of flexible wires which, along with the cylinder, take on the main carding action. In addition to carding, tops are designed to collect trash, dust and short fibers.
Revolving tops are available in different heights and with varying PPSI, selected in accordance with production level and spinning process.
Tops with high PPSI are recommended for fine ring-spun yarn; tops with low PPSI are primarily used for coarse ring-spun yarn and open-end yarn.
Stationary flats and stationary flat systems
Stationary flats in the pre and post carding zone, along with the revolving tops, provide for additional carding.
In the pre carding zone the raw material should be prepared in such a way that the load on the flats is limited. Large fiber tufts are opened into smaller fiber tufts by the stationary flats. In the post carding zone further carding takes place in which the fibers are again parallelized and individualized.
If cotton is being processed then the fiber of the stationary flats in the pre and post carding zone must be prepared in such a way that trash and dust can be removed by the mote knives.
Groz-Beckert also supplies stationary flat systems for carding, consisting of 2 to 22 stationary flats, depending on card type and model. Moreover, one or more extraction units can be connected to the system for trash removal.
Cleaning fillets are used for cleaning rollers for stripping rollers and for revolving tops.
The cleaning roller of the stripping roller prevents lapping of the stripping roller, while cleaning rollers for revolving tops remove the flat strips from the revolving tops. For good carding results and for keeping the card sliver clean, flat strips must be completely removed.
Raw materials arrive at spinning mills in compressed bales. They are opened and cleaned in the blowroom, which subjects the material to high stress.
The high speeds of the beater rollers can create neps which diminish yarn quality and therefore must be removed by the carding process.
Yet high beater speeds are beneficial to intensive cleaning of the cotton and require a compromise between cleaning efficiency and nep generation in order to achieve good results. It is thus linked to some fundamental considerations:
- The wires used must be adapted to the process sequence. The cleaning and opening positions in the blowroom should become finer.
- The front angle of the wire is crucial to cleaning efficiency. A larger angle implies more aggressive opening of fibers and hence more intensive cleaning. The use of less aggressive clothing is recommended for finer fibers.
- Wear on the wire lowers the intensity of the cleaning and opening process of the raw material. For consistent quality it is therefore important not to use worn wires.
Border wires are necessary to securely fasten the beginning and the end of card wires onto a roller and are embedded in the grooves at the edge of the rollers.
Border wires are removed and replaced when ever grinding of a roller is necessary.
Product services Carding
This service includes dismantling, mounting, assembly and start-up of cards.find more
Information about the carding portfolio in form of brochures and videos can be found in the media Center.find more
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