COMBER & COMBING ACTION

Introduction: Combing is a very important process for a spinning mill. The object of combing is removal of short fibres, Neps, impurities and to improve the fibre length uniformity followed with improvement in mean length. The removal of immature cotton, foreign matter and improvement in fibre fineness and fibre bundle strength are the additional advantages of combing process. In totality combing process significantly improves the cotton characteristics by removing the useless fibres (i.e. Fibres which are not suitable for a particular end use) from the process. These fibres are extracted as comber Noil waste. This Complete combing process carried out by action of different combing elements. During combing process along with useless fibres good quality fibres are also removed especially in modern high speed combers which are huge raw material & financial losses for the industry. We have studied in detail the combing action of these different combing elements w.r.t. removal of Neps, SFC % & other impurities with mean length improvement. The object of this article is to present the effect of different combing elements on cotton processed and how we can perfectly set these combing elements to get the better combing process with respect to desire Quality, so we can achieve maximum removal of useless fibres with minimum losses of good fibres.

Keywords:

Comber, Combing elements, Top Comb, Top comb penetration, Top comb penetration depth, Feed/Nips, Nips/Minutes, Lap batt, Sliver, Noil, Unicomb, Afis Pro, Imperfection, classimat faults.

History of Comber:

There are two competing combing technologies: the Noble (1853) comb (variants Lister, Heilman (1846) and Holden) and the French comb. The Noble comb technology is inefficient, hence most combing in the world is carried out on the French system. The French system is superior as it combs the entire length of a fiber. Noble combs suffer from the problem that they will not comb 2 mm of a fiber's length. The 2 mm is the distance between counter-rotating pins. The French system is a rectilinear combing system as opposed to earlier woollen systems

developed in England. Although the Heilman and Noble comb was an original circular design (also developed in min and 18–19th-century England) as it happens in modern history, English mills didn't share technology – resulting in development of superior technology on continental Europe in the mid-19th century, as in France.

Combing: It is the process which is used to upgrade the raw material. It influences the following yarn quality

yarn evenness strength cleanness smoothness visual appearance

In addition to the above, combed cotton needs less twist than a carded yarn.

TASK OF THE COMBER:

To produce an improvement in yarn quality, the comber must perform the following operation.

elimination of short fibres as noil. elimination of remaining impurities . elimination of neps.

The basic operation of the comber is to improve the mean length or staple length by removing the short fibres.

Trailing hooks from carding should be fed as leading hooks to reduce long fibre loss in the noil.

The Combing Process: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:

1. Elimination of precisely pre-determined quantity of short fibers; 2. Elimination of the remaining impurities; 3. Elimination of a large proportion (not all) of the neps in the fiber material; 4. Formation of a sliver having maximum possible evenness; 5. 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:-

1. Rectilinear comber (with stationary or oscillating nippers), 2. Circular combers (English worsted process), 3. Rotary comber (production of Schappe spun yarns) and 4. Hackling machines (bast fibers).

The Combing Machine:

The basic elements of the combing machine are shown in figure. These are the feeding element, the nipper plate, the combing system and the detaching rollers. 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.

SEQUENCE OF OPERATION IN A COMBER

Feeding, lap is fed by feed roller fed lap gripped by the nipper gripped lap is combed by circular comb detaching roller grips the combed lap and moves forward while the detaching roller delivers the material, top comb comes into action to further

clean the lap While going back, nipper opens and receives a new bit of lap.

Types of feeds:

1. Forward feed (concurrent feed):Feed of the sheet into the nippers occurs while the nippers move towards the detaching roller

2. Backward feed (counter-feed): Feed of the sheet occurs during return of the nippers.

PRODUCTION CALCULATIONSProduction of the comber is dependent upon the following:

N- Nips per min S- feed in mm/nip G- lap weight in g/m K- Noil percentage A- tension draft between lap and feed roller(from 1.05 to 1.1) E- efficiency

THERE ARE 8 COMBERS IN HALL 1&2

No of heads=8 Noil %=16.5% Nips/min=450-458 Feed/nip=4.7-5.2mm Length of delivery=6290 Delivery rate=215m/min Drafting system=3/3 Noil suction pressure=12-15mm of water column Time taken to fill up a can=29min Sliver weight=4.720ktex

Technical data:

Manufacturer: Rieter Model: E65 Year: 2006 Nos. 8

Input feed:

Lap width: 270-300mm No. of lap per machine: 8 Batt weight per meter: 60-80 gm/mt

Production data:

Lap diameter: up to 650mm Feed per nip: 4.3/4.7/5.2/5.9mm Noil: 8-25 % Drafting system: 3/5 Doubling: 8 fold Sliver weight: 3-6 kTex Break draft: 1.14-1.5 Total draft: 9.0-23.1

Pressure:

Loading: pneumatic Top detaching roller: 3-4bar Drafting system front roll: 2.5-3bar Drafting system 2nd and 3rd rolls: 3.5-4.5bar

Parameter that affects Noil%:

• The feed amount moved per cycle:• The type of feed: Forward feed or backward feed;• The detachment setting;• The point density on comber;• The depth of top comb penetration:• Fiber length distribution in comber lap

• Count of comber lap• Type of Hook Present in comber lap

Analysis by figure:

Conclusion:

All the above informations are collected for the acknowledgement of textile spinning learning purpose. Thank you for enjoying.