The combing process is normally used to produce smoother, finer, stronger and more uniform yarns. Therefore, combing is commonly confined to high grade, long staple natural fibers. In recent years, combing has been utilized for upgrading the quality of medium staple fibers. In addition, a yarn made of combed cotton needs less twist than a carded yarn. However, these quality improvements are obtained at the cost of additional expenditure on machines, floor-space and personnel, together with a loss of raw material. Yarn production coast is increased by something under 1 US$/Kg of yarn (depending on the intensity of combing).
To improve the yarn quality, the comber must perform the following operations:
- Elimination of precisely pre-determined quantity of short fibers;
- Elimination of the remaining impurities;
- Elimination of a large proportion (not all) of the neps in the fiber material;
- Formation of a sliver having maximum possible evenness;
- Producing of more straight and parallel fibers.
Elimination of short fibers produces an improvement mainly in staple length, but also affects the fineness of the raw material. The micronaire value of combed sliver is slightly higher than that of feedstock (elimination of dead fibers). Also the degree of parallelization might reduce the inter-fiber adhesion in the sliver to such an extent that fibers slide apart while being pulled out of the can – i.e. sliver breaks or false drafts might be caused.
Types of Comber:
The major types of combers include:
- Rectilinear comber (with stationary or oscillating nippers),
- Circular combers (English worsted process),
- Rotary comber (production of Schappe spun yarns) and
- Hackling machines (bast fibers).
The basic elements of the comber machine are shown in below figure. These are the feeding element, the nipper plate, the combing system and the detaching rollers. The feeding element consists of a feed plate and feed roll. The main function of the feeding element is to feed the comber lap in a series of short lengths. The nipper plate grips the fibers as a means of holding long fibers while the short fibers, neps, and trash are being removed. The combing system consists of two combs. The first one is a rotating bottom circular comb that performs the main combing action. The second one is a linear top comb that completes the function of the bottom comb through vertical combing movement.
The detaching rolls are two pairs of gripping rolls that rotate forward and backward in intermittent fashion to hold and move the combed web for a net forward travel.
The objectives of combing mentioned earlier are accomplished by a precise sequence and synchronized series of actions performed by the combing elements. The following text will review this sequence of actions, or the combing cycle, in a very simplified manner to demonstrate the function of each comber component.
Major Manufacturers of Comber Machine:
- Marzoli Spa, Italy
- Laxmi Machine Works Limited
- Toyoda Textile Machinery, Japan
- Rieter Machine Works Limited, Switzerland
- Zhejiang Huahai Group, China.