Modern Comber Machine
Modern comber machine is essential equipment in textile spinning industry for producing high-quality, fine, and uniform yarns by removing short fibers, neps, and impurities from cotton slivers after carding. Modern comber machines are highly advanced, offering improved productivity, efficiency, and yarn quality.
Over the number of years, lots of changes have taken place in structuring and redesigning the comber. Even then the basic combing operation such as lap feeding, combing by cylinder or even detachment of combed fleece and joining of the two fringes have remained the same. Thus, the general comber appearance has been more or less unchanged.
However, restructuring and redesigning of parts has enabled the removal of complicated driving mechanisms and has further helped in reducing the number of parts as well as their weight. The maintenance of the comber has been simplified; the oiling and greasing procedures are made easy by using non-oil and sintered bushes, centralized oil pumps and plastic pipe connections leading to various important rotating parts. For greasing, the nipples are provided and with the help of grease guns, the operation can be done during working.
Even for the machine operator, the workload has been considerably reduced and his mind is made free due to various electrical stop motions. Thus, his operating efficiency either for the same number of machines, or even for a little more, is improved. The basic aim of adopting these various improvements is to attain higher production rates at the comber. As compared to conventional machines, present modern machines are capable of working with very heavy laps (from 20 g/m to 70 g/m and above) at remarkably higher speeds (from 90 nips/min to more than 300 nips/min). The number of heads is increased from six to eight. Some modern machines have double-sided workings. A larger diameter coiler has enabled the use of larger cans. All this has helped to increase the production from 30 kg/shift to 60 kg/hr. However, it is equally important to note that on and above these improvements in production rates, the quality of the product – comber sliver – has been significantly improved.
Why Combing is Essential?
Before diving into parts: combing is the critical upgrade after carding. It:
- Removes short fibers (<12mm) and impurities (neps, seed fragments)
- Aligns fibers parallel for smoother, stronger yarn
- Makes fabrics softer, more lustrous (think high-thread-count bed linens)
Without combing? Yarn gets hairy, weak, and pills easily.
Features and Parts of Modern Comber Machine
A comber machine consists of several important parts, each with a specific function in the combing process. Modern comber machines are equipped with advanced technology and several features that enhance their performance. Major features and parts of a modern comber machine are discussed below.
1. Feed
Apart from the usual tension compensator provided to take up the slackness during the backward motion of the nipper assembly, modern machines provide an easy changeover from forward to backward feed and vice-versa. Some of the models have continuous feeding arrangements.
2. Nippers
In place of the normal driving of the nippers in traditional combers using hinged support, the two rocker arms, loosely fulcrumed around the cylinder shaft gives forward and backward movement to the nipper assembly. With this, the nippers move in a concentric arc around the cylinder. The nipper plate is also redesigned to reduce its size and weight. The pressure on the top nipper is exerted by the springs which are compressed when the nippers move back, thus exercising adequate and uniform pressure on either side of the top nipper.
2.1 PP Nippers:
The PP nipper is an additional gripping nipper (Figure 2) provided to grip the fibers during the piecing-up operation. Normally with conventional combers, it is possible that, at the time of the entry of the top comb, the front end of some long fibers fails to reach detaching roller nip. These fibers are stopped by the top comb.
2.2 Modern Nipper Assembly:
In a high-speed comber, the designing of the nipper framing becomes very important. During a combing cycle, the nippers accelerate and slow down twice in each cycle. With a speed of more than 300 nips per minute, this turns out to be almost five times per second. The nippers are, therefore, required to be very light in weight and hence are made of aluminium. Further, as the heavy laps are processed, the lap sheet is almost double in thickness.
2.3 Movement of the Nippers:
Two pivot levers, one each on either side support the bottom nipper plate (Figure 3). These pivot levers are loosely held around the cylinder shaft and are also supported by the two swing arms which are screwed to the nipper shaft.
3. Cylinder Needling
The conventional combers used half-lap with 20 rows. The earlier versions of modern combers reduced the number of rows from 20 to 17. In present days, almost all modern combers use ‘UniComb’ or ‘Hi-Comb’ or ‘circular comb‘ segments.
They are equipped with saw-tooth metallic wires and are fitted exactly in the same place where the conventional half-lap was mounted.
A lot of developments have taken place in UniComb in terms of different characteristics. The circumference of the comb over the cylinder also varies from 75° to 110°. In general, the larger the angle the more the spread of wire points. However, the best choice depends on the type of cotton used. In any combing operation, the direction of the motions of the combing segment and that of the nippers is very crucial. The action is much more effective when the two are opposite.
4. Top Comb
It is carried by an additional bracket mounted on the nipper framing. Thus, the comb moves along with the nipper assembly. The circular path of the nipper assembly ensures that the top comb automatically comes into operation (Figure 4 (a)) when the nippers move forward and are close to detaching rollers. This avoids any additional motion to be given to the top comb.
In modern comber the top comb is detachable. The depth of the top comb into the fringe can be altered by adjusting it with the help of securing a screw (Figure 4 (b)).
So also, its distance from the detaching rollers can be adjusted. Like conventional combers, the top comb on modern combers also finds its position in between the nippers and the detaching rollers. The top comb holder carries a needle bar to which the fine needles of the top comb are attached. The needles are flat and slightly bent at the bottom. They are soldered to the needle bar. The top comb is carried by the bottom nipper plate so that it swings along with the nipper movement.
5. Detaching Rollers
Unlike conventional combers, there is no swinging of the back top detaching roller. The forward and backward rotation of bottom detaching rollers is achieved through ‘sun and planet’ or any other modern type of differential mechanism. With this, therefore, detaching rollers are hardly stationary. They slowly move forward to deliver the fringe and move backward at a faster speed to bring back the already combed fringe for piecing.
Special helical flutings are made on bottom steel detaching rollers. The top roller cots are specially designed to take care of both their hardness and anti-static nature. This, on one hand, improves the detaching roller grip and at the same time reduces lapping tendencies. The weighting system on the top detaching rollers is of spring type with the saddle arrangement or pneumatic type with special weighting hooks. The weight-releasing handles or switches are provided in the case of cleaning of top detaching roller. Some combers have detaching rollers of smaller diameters. This facilitates the combing of short-staple cottons and thus makes the machine more versatile.
6. Web Condensation and Sliver Table
As stated earlier, the trumpet in front of detaching roller to collect the web is situated asymmetrically. This reduces all the ill effects of the piecing wave. The table calendar rollers are heavy and have coarser flutes for better gripping action. As there are eight heads, the slivers have to pass over a longer distance over the surface of the sliver table. The table surface is, therefore made quite smooth by giving a special plating. This helps the head sliver to pass over the table without any stretching. An additional calender roller is provided halfway along the table length to avoid the dragging of slivers.
7. Draw-Box
The common drafting system used in the draw-box is of the type – 2/2, 3/4, 4/5 or 5/4. The top rollers are weighted with an over-arm weighting system or with pneumatic weighting. The gauge is provided in the latter case to enable reading of the correct pressure. The bottom rollers have special flutes and are equipped with needle-bearing bushes. The slivers are fed to the coiler calender rollers in the usual way, i.e., four slivers are grouped together and two such emerging sliver groups are coiled separately with either a twin coiling or bi-coiling system. The draw-box draft is reduced to deliver a coarser sliver. This reduces the possibility of its stretching in a subsequent process.
7.1 Typical 5/4 and 2/2 Drafting Systems:
Different drafting systems are used in the comber draw-box. Apart from precision in controlling the shorter fibers, the drafting capacity of the system also becomes important. One such typical system is shown in Figures 5 and 6. The 5/4 drafting system can give a draft of up to eight with an eight-head comber. With a reduction in the draft, a thicker sliver can be produced. Usually, a single coiler system allows a can-changing mechanism to reduce the workload. With a 2/2 drafting (Figure 7), as mentioned earlier, the phasing of the piecing waves is considerably reduced as there is only a single drafting zone. However, the draft that can be employed is limited. This is taken advantage of by using a bi-coiling system, where the two slivers of the normal thickness emerge.
8. Coiler
With higher production rates, the coilers are required to be redesigned to accommodate larger cans. As mentioned above, they are provided with a twin coiling, bi-coiling system or one similar to a conventional single-sliver system. The hank meters are provided to register a certain length of sliver into the can. They also register the total production in hanks at the end of every shift. On some machines, an automatic can-changing arrangement is provided. This helps to reduce the workload of the tenter who has to only put empty cans in the stock of the creel and take out automatically delivered full cans.
9. Larger Diameter of Cylinder
In some modern combers, the total covering area (Figure 8 (a)) for the pins or the saw-tooth points is increased.
Therefore, the larger combing surface leads to improved cylinder combing action. The needle or saw-tooth sector covers 113.5° in place of the earlier segment which only covered 86°.
Figure 8 (b) shows the needling of a typical modern comber and the clearance for the needle points from the bottom nipper. This is another needling arrangement which has been found to be more effective in short-fiber removal during main cylinder combing action. A small variation is seen in the last few needle rows. These rows remain at a constant distance from the bottom nipper. In the earlier model, this distance from bottom nippers was slightly increased.
10. Avoiding Inverse Airflow by Brush
The suction through the aspirator always demands an air supply from and around the brush section. The air needs to be drawn from this section, which is partly guided around the cylinder. In a conventional comber, a small proportion of air managed to get through the space between detaching rollers, over which, the pieced-up portion of the web was being passed.
11. Nylon Filters
In conventional combers, the aspirator draws the air from the brush shaft region. The air thus drawn cleans the brush and brings an air-noil mixture onto the perforated surface of the aspirator. The separation of noil and air takes place at the perforated surface of the aspirator. However, the perforations do allow a small percentage of very short fibers along with the fine dust to pass through them.
12. Head-Stock
The head-stock is placed in a closed compartment and only the main shaft ‘V’ pulley receiving the drive from the motor, projects out. In some cases, even the motor itself is enclosed. The detaching roller differential motion drive is placed in an air-tight compartment which is invariably immersed in an oil bath. A master gauge is provided for altering the step gauge settings on all heads simultaneously. In the Rieter comber, a slow motion arrangement is provided for driving all the parts except the brush shaft at regular intervals. This helps in the periodic cleaning of the half-lap. It thus helps in improving the combing action by the cylinder needles and reduces the neps in the web. There is a time switch provided for this operation.
In high-speed combers, the increase in production is made possible through the following things:
- Higher nips/min
- Heavier lap feed
- Higher feed length
- More number of heads per machine
- Better machine efficiency – bigger feed and delivery packages
- Better operating efficiency and
- Reduced maintenance time
13. Combing Parameters and Yarn Quality
Apart from the improved mechanical design and the ease of operations, the developments in combers offer several other advantages such as efficient combing of short and medium cottons to improve their spinning value, reduction in comber noil without adversely affecting yarn quality, increase in the productive capacity of the machines to reduce manufacturing cost, etc.
14. Comber Lap
With given settings of comber, the waste extracted generally increases with higher lap weights. Lap prepared with a low number of doublings and draft shows a greater increase in waste percentage as the lap weight increases. The condition aggravates when a longer feed length is used. It is observed that, with poor fiber control during the lap preparation, the heavier laps tend to produce inferior yarn in terms of Count strength product (C.S.P.).
15. Comber Waste
The percentage of waste extracted at the comber mainly depends upon the characteristics of cotton fiber and the extent to which an improvement in the yarn quality is desired.
The effect of combing different types of cottons:
- Extraction of large percentages of comber waste improved the mean length progressively. However, this mean length did not exceed that of raw cotton.
- The fiber length irregularity in the combed material decreased with an increase in comber waste.
- Up to 15% comber waste, there was an improvement in the yarn strength by 10% over that of carded yarns. For still higher waste from 18% to 25%, the strength improvement over that of carded yarns was about 18%. This suggests that improvement in the yarn strength, with the former being due to better fiber orientation and parallelization; whereas with the latter, it was due to improvement in mean length and fiber length regularity.
16. Waste Level and Comber Settings
A higher comber waste through a set of finer comber needling arrangements (both needle count and their spacing) for superior quality mixings helps in mainly reducing neps. However, the feed, in this case, should not be too heavy. Similarly, higher waste through deeper top comb penetration appears to have a significant effect on the imperfections in the yarn. However, due care must be taken to see that the level of top comb penetration does not affect the orderly arrangement of the comber web during piecing and detachment.
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Conclusion
Modern comber machine, with their advanced features and precisely engineered parts, play a pivotal role in producing premium-quality yarns and driving efficiency in contemporary spinning mills. Their advanced features, high production capacity, and precise parts make them indispensable in modern spinning mills. By understanding the parts and features of a modern comber machine, operators and technicians can better optimize machine performance and product quality.
References
[1] Khare, A. R. (2023). Principles of spinning: Combing in Spinning. CRC Press.
[2] Kumar, R. S. (2014). Process management in spinning. CRC Press.
[3] Purushothama, B. (2011). A practical guide to quality management in spinning. In Woodhead Publishing Limited eBooks. https://doi.org/10.1533/9780857093950
[4] Purushothama, B. (2012). Training and development of technical staff in the textile industry. In Woodhead Publishing Limited eBooks. https://doi.org/10.1533/9780857095848
[5] Purushothama, B. (2016a). Handbook on cotton spinning industry. CRC Press.
