Combing process is an expensive process to manufacture high quality yarns meant for specific end uses. The objective of the comber is to remove the short fibers and impurities from the cotton material, improve the uniformity of the sliver produced for further processes. Combing is done in order to increase the mean fiber length by effectively eliminating short fibers. It also enhances the luster of the fibers slightly and helps in parallelizing them for better alignment.
Types of Defects in Comber: Causes and Remedies
Various types of defects occur in comber machine due to machine settings, poor maintenance, or fiber quality issues. Below are common defects, their causes, and remedies:
A. Inadequate Removal of Short Fibers and Neps
The various causes of inadequate removal of short fibers and neps in the combing process and the remedial measures taken to control the fault occurrence are given below:
Causes:
- Head-to-head variation in comber noil%
- Uncombed portions due to slippage under feed roller
- Slippage of fibers under detaching rollers
- Plucking of fibers by half lap from nipper grip
- Web disturbance due to air currents due to defects in brush or/in aspirator
Remedies:
- Check noil% in individual heads and rectify the head that deviates.
- Check feed roller setting in individual heads and rectify.
- Check the condition of detaching roller cots and condition of the gears driving bottom detaching rollers.
- Check the machines thoroughly for bent and hooked needles on half lap and top comb.
B. Short-Term Unevenness
The various causes of short-term unevenness in sliver in the combing process and the remedial measures taken to control the fault occurrence are given below:
Causes:
- Piecing waves
- Drafting waves
- Poor fiber control due to worn-out top roller cots in draw box
- High or low tension draft and improper settings
Remedies:
- Check for eccentric detaching rollers and correct it.
- Check U% and make use of spectrogram diagram to identify the source of the problem. Check for eccentric rollers in drafting zone and correct them. Check for the drafting rollers setting.
- Proper maintenance of top roller cots.
- Correct the setting of tension draft and other settings as per norms.
C. Hank Variations
The various causes of hank variations in the combing process and the remedial measures taken to control the fault occurrence are given below:
Causes:
- Singles due to improper functioning of stop motions in the creel.
- Improper selection of tension draft.
- Rough surface of the sliver table that creates stretch in sliver.
- Variation in the feeding lap.
- Lap licking while unwinding.
- Hank variation between combers is high.
Remedies:
- Check the functioning of stop motions frequently.
- Proper selection of tension draft.
- Proper polishing of the sliver table.
- Correct the variations in feed lap.
- Set correct precomb draft. Maintain correct R.H%.
- Check the combers for variations in lap roller feed per nip, draft wheels on draw box, tension drafts at tables, draw box and coiler, and noil level variations.
D. Higher Sliver Breaks at Coiler
The various causes of higher sliver breaks at coiler in the combing process and the remedial measures taken to control the fault occurrence are given below:
Causes:
- Rough surface of sliver guides
- Eccentric coiler calender rollers
- Tension draft too high
- Higher precomber draft, i.e., excess parallelization of fibers in the sliver
Remedies:
- Sliver guides to be maintained properly.
- Check for eccentricity in coiler calendar roller and rectify it.
- Set appropriate tension draft.
- Optimum precomber draft.
E. Coiler Choking
The various causes of coiler choking in the combing process and the remedial measures taken to control the fault occurrence are given below:
Causes:
- Wax and trash deposited in coiler obstruct sliver passage and chocks.
- Too many thick places, undrafted places in the sliver.
- Wrong sliver mending procedure after drafting while attending breakage.
- Higher R.H%.
Remedies:
- Proper cleaning of coiler parts where sliver passes with a rope.
- Proper maintenance of drafting zone, top rollers, correct setting of drafting rollers.
- Proper training of tenter for correct sliver mending procedures.
- Maintain recommended R.H%.
F. Web Breakages at Drafting Zone
The various causes of web breakages at drafting zone in the combing process and the remedial measures taken to control the fault occurrence are given below.
Causes:
- Spreading of web too much
- Defects in gears, burrs in bottom rollers
- Improper tension drafts
- Wax deposition and trash accumulations at trumpet
- Poor buffing of top roller cots
Remedies:
- Correct positioning of web width guides.
- Check gears for any fault and rectify it. Check for burrs and rectify.
- Set tension draft as per norms.
- Clean the trumpet regularly with petrol.
- Ensure proper buffing procedures.
G. Breakages in Comber Heads
The various causes of breakages in comber heads in the combing process and the remedial measures taken to control the fault occurrence are given below:
Causes:
- Tight or slack web
- Improper positioning of web trays
- Unclean web trays
- Improper functioning of clearer rollers in detaching section
- Trumpets set too far away from the nip of calender rollers
Remedies:
- Maintain lap tension properly.
- Proper positioning of web trays.
- Clean the web trays frequently.
- Clean the clearer rollers frequently.
- Correct the setting of trumpet from the nip of calender rollers.
H. Excessive Lap Licking and Splitting
The various causes of excessive lap licking and splitting in the combing process and the remedial measures taken to control the fault occurrence are given below:
Causes:
- Improper tension drafts and roller setting
- Higher precomber draft
- Uneven lap and tight winding
Remedies:
- Set optimum tension draft and roller setting.
- Set optimum precomber draft.
- Ensure good lap quality and set proper winding tension during lap winding.
I. Head to Head Variation
Head-to-head variation in comber refers to inconsistencies in fiber length, weight, or sliver evenness between two adjacent combing heads. This fault can negatively affect yarn quality and uniformity.
Causes:
- Insufficient draft in lap preparation.
- Bad mechanical condition of lap making machine like bent weighting hooks, defective top rollers and variation in top roller pressure.
- Bad condition of comber machine parts like brush, half lap, top comb, etc.
- Difference in top comb penetration from head to head.
- Poor nipper grip and bent nipper on some of the heads.
- Difference in ratchet gear, count change gears and tension change gears between combers working on given mixing.
Remedies:
- Ensure proper draft in lap preparation.
- Maintain good mechanical condition of the lap-making machine.
- Regular maintenance of comber parts.
- Standardize top comb penetration.
- Optimize nipper grip and condition.
- Ensure uniform gear ratios across combers.
Conclusion:
Comber defects process can significantly impact yarn quality, decrease efficiencies and production losses. Common defects such as neps, slubs, short fiber content, clipping, broken ends, yarn imperfections, and drafting problems arise due to improper machine settings, poor raw material quality, and inadequate maintenance. A well-optimized combing process enhances fiber alignment, reduces waste, and improves the overall quality of the final yarn, ensuring better performance in subsequent spinning processes.
References:
[1] Kumar, R. S. (2014). Process management in spinning. CRC Press.
[2] Purushothama, B. (2011b). A practical guide to quality management in spinning. In Woodhead Publishing Limited eBooks. https://doi.org/10.1533/9780857093950
[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.
[6] Kiron, M. I. (2021c, October 31). Problems / Defects / Faults of Combing Process with Causes and Remedies. Textile Learner. https://textilelearner.net/problems-in-combing-process/
[7] Textile-Engineering. Mechanical faults in comber machine. Textile Engineering. https://textileengineering.net/mechanical-faults-in-comber-machine/