Classification of Yarn Faults [PDF]

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Classification of yarn faults 1. Low cop content: yarn content in the cop is less 1.1. EFFECT Efficiency loss in ring frame •Drop in winding efficiency •More knots for a given length of wound yarn 1.2. CAUSES Under utilisation of bobbin height  Lower number of coils /inch  Higher chase length  Cop bottom bracket properly not set  Improper selection of ratchet  Ratchet pawl pushing number of teeths/movment in the ratchet wheel  Spinning empties wall thickness is high 1.3. RECTIFICATION Optimum chase length, coil spacing and wall thickness of empy cops tobe ensured  Ratchet/pawl movement to be properly set  Free space of only 7.5mm to be maintained at the top and bottom of the cop  Free space only 0.75mm only to be maintained between full cops and the ring 2. Slubs: an abnormally thick place or limp in yarn showing less twist at that place 2.1. EFFECT More end breaks in the next process.  Damaged fabric appearance.  Shade variation in dyed fabrics. 2.2. CAUSES  Accumulation of fly and fluff on the machine parts.  Poor carding.  Defective ring frame drafting and bad piecing  Improperly clothed top roller clearers. 2.3. RECTIFICATION  Machine surfaces to be maintained clean.  Proper functioning of pnemafil/roller clearers to be ensured.  Broken teeth gear wheel to be avoided and proper meshing to be ensured.  Better fiber individualisation at cards to be achieved.  Optimum top roller pressure &back zone  Setting at ring frame to be maintained. 3. Neps : Yarn containing rolled fibre mass, which can be clearly seen on black board at close distance; measurable on Uster imperfection Indicator. 3.1. EFFECT



Damaged fabric appearance •Shade variation in the dyed fabrics •An abnormally thick place or lump in yarn showing less twist at that place is called slubs 3.2. CAUSES Accumalation of fly and fluff on the machine parts  Poor carding.  Defective ring frame drafting and bad piecing  Improperly clothed top roller clearers. 3.3. RECTIFICATION Machine surfaces to be maintained clean.  Proper functioning of pnemafil/roller clearers to be ensured.  Broken teeth gear wheel to be avoided and proper meshing to be ensured.  Better fiber individualisation at cards to be achieved. 4. Snarl : Yarn with kinks(twisted onto itself)due to insufficient tension after twisting 4.1. EFFECT Entanglement with adjacent ends causing a break •Damaged fabric appearance •Shade variation in dyed fabrics •Improper meshing of gear wheels •Mixing of cottons varying widely in fiber lengths and use of immature cottons 4.2. CAUSES Higher than normal twist in the yarn  Presence of too many long thin places in the yarn 4.3. RECTIFICATION Optimum twist to be used for the type of cotton processed  Drafting parameters to minimise thin places in the yarn to be adopted  The yarn to be conditioned  Correct tension weights and slub catcher settings to be employed at winding 5. Thick and thin places : Measurable by Uster Imperfection Indicator and observable on appearance 5.1. EFFECT Eccentric top and bottom rollers •Insufficient pressure on top rollers •Worn and old aprons and improper apron spacing •Improper meshing of gear wheels •Mixing of cottons varying widely in fiber lengths and use of immature cottons



5.2. CAUSES Eccentric top and bottom rollers  Insufficient pressure on top rollers  Worn and old aprons and improper apron spacing  Improper meshing of gear wheels  Mixing of cottons varying widely in fibre lengths and use of immature cottons 5.3. RECTIFICATION Eccentric top and bottom rollers to be avoided  Top arm pressure checking schedules to be Maintained strictly  Wide variation in the properties of cottons used in the mixing to be avoided  Better fiber individualisation at cards to be achieved.  Correct spacers to be utilized 6. Soft yarn: Yarn which is weak indicating lesser twist 6.1. EFFECT: More end breaks in subsequent processes •Shade variation in dyed fabrics 6.2. CAUSES: Slack tapes dirty jockey pulleys   



Improper bobbin feed on the spls Less twist in the yarn Bad clearing at the travellar 6.3. RECTIFICATION: Vibration of bobbins on the spindles to be avoided  Proper yarn clearing to be ensured  Periodic replacement of worn rings and travellars to be effected Yarn stained with oil 7 15. EFFECT Damaged fabric appearance •Occurrence of black spot in fabric CAUSES Careless oil in the moving parts,over head pulleys etc Piecings made with oily or dirty fingers Careless material handlings RECTIFICATION Appropriate material handling procedures to be followed 1. Oilers to trained in proper method of lubrication 2. Clean containers to be utilised for material transportation 16. Very small snarl-like places in the yarn which disappear when pulled with enough tension or Yarn with spring –like shape 8 17. EFFECT More breaks in winding •More noticable in polyester and cotton blended yarns CAUSES Mixing of cottons of widely differing staple length Closer roller settings



Eccentric top and bottom rollers Non optimum temperature and relative humidity in the spinning shed Over spinning of cottons RECTIFICATION Optimum top roller pressure to be maintained 1. Mixing of cottons varying widely in fibre length to be avoided 2. Use of optimum roller settings 3. Use of properly buffed rollers free from eccentricity to be ensured 18. Unduly thick piecing in yarn caused by over End piecing 9 19. EFFECT More end breaks in subsequent process •Increase in hard waste CAUSES Wrong method of piecing and over end piecing Twisting the ends instead of knotting RECTIFICATION Tenters to be trained in proper methods of piecing 1. Separators to be provided 2. Excessive end breaks in spinning to be avoided 20. Slub in the yarn stained with oil 10 21. EFFECT More end breaks in the ensuring process •Damaged fabric appearance •Shade variation in dyed fabrics CAUSES Accumulation of oily fluff on machinery parts Poor methods of lubrication in preparatory processes Negligence in segregating the oily waste from process waste RECTIFICATION Yarn contact surfaces to be kept clean 1. Oilers to be trained in correct procedures of lubrication 2. Proper segregation of oily waste from process waste 22. Presence of black specks of broken seeds, leaf bits and trash in yarn 11 23. EFFECT Damaged fabric appearance •Production of specks during dyeing •Needle breaks during knitting •Poor performance during winding CAUSES Ineffective cleaning in Blow room and cards Use of cottons with high trash and too many seed coat fragments RECTIFICATION Cleaning efficiency of blow room and cards to be improved 1. Optimum humidity in the departments to be ensured



24. Protrusion of fibre ends from the main yarn structure 12 25. EFFECT More end breaks in winding •Uneven fabric surface •Beads formation in the fabric in the case of polyester/cotton blends CAUSES Use of cottons differing widely in the properties in the same mixing Use of worn rings and lighter travellars Maintaining low relative humidity, closer roller settings and very high spindle speeds RECTIFICATION Use of travellars of correct size and shape and rings in good condition to be ensured 1. Periodic replacement of travellars and suitable 2. Roller settings to be maintained 3. Optimum relative humidity to be maintained in the spinning room 4. Wide variation in the properties of cottons used in the mixing to be avoided 26. Metallic parts, jute flannel and other similar foreign matters spun along with yarn 13 27. EFFECT Breaks during winding •Formation of holes and stains in cloth •Damaged fabric appearance CAUSES Improper handling of travelers Improper preparation of mixings RECTIFICATION Removal of foreign matters(such as jute fibres,colour cloth bits) to be ensured during preparation of mixing 1. Installation of permanent magnets at proper 2. Places in blow room lines to be ensured 28. Fly or fluff either spun along with the yarn or loosely embedded on the yarn 14 29. EFFECT More breaks in winding CAUSES Accumulation of fluff over machine parts Fanning by workers Failure of over head cleaners Malfunctioning of humidification plant RECTIFICATION Machinery surfaces to be kept clean by using roller pickers 1. Fanning by workers to be avoided 2. Performance of over head cleaners and humidification plants to be closely monitored 30. It is a double yarn which one yarn is straight and other is coiled over it 15 31. EFFECT Breaks during winding •Causes streaks in the fabric CAUSES Feeding of two ends (instead of one ) in ring frame Lashing -in ends in ring frame RECTIFICATION Tenters are to be trained in piecing methods(or) practices 1. Pneumafil ducts to be kept clean and properly set 32. Coils of yarn coming out of the ring cops in bunches at the time of unwinding 16 33. EFFECT Increase in end breaks •Higher yarn waste CAUSES Improper ring rail movement Worn builder cam Loose package and excessive coils in the package Soft build of cops Improper empties fit on the spindles and slack tapes RECTIFICATION Ring rail movement to be set right •Optimum ratio of winding: bindings coils and optimum chase length to be maintained 34. Damaged layers on the surface of the ring cops 17 35. EFFECT Excessive breaks during winding • More hard waste at winding CAUSES Spindle or empty cops wobbling  Use of lighter travellers snd incorrect ratchet wheel  Movement of spindles to the rings not concentric RECTIFICATION Worn spindles to be replaced 1. Improper fit of empty cops with spindles to be avoided 2. Gauging of spindles with rings to be properly carried out 3. Use of right type travellar and ratchet wheel to be ensured 36. Step-like appearance of the cop 18



37. EFFECT Slough-off during doffing/winding • More breaks during unwinding(due to slough off) • Higher hard waste in winding CAUSES Improper combination of ratchet and pawl  Jerky ring rail movement(pocker rod movement to check) RECTIFICATION Ratchet and Ratchet/pawl movement to be accurately arrived at taking into consideration 1. Count of yarn, ring dia and chase length 2. Lubrication of pocker rods at appropriate interavels to be carried out 38. Ends not laid properly on the cone at reversal of yarn path 19 39. EFFECT More end breaks in the subsequent process • Excessive yarn waste CAUSES Vibrating and wrongly set cone holder  Yarn coils wrapped round the base of cone holder  Traverse restrictors fixed at incorrect position  Improper alignment of tension brackets with the drum RECTIFICATION Maintenance cone winders to be good 1. Cone holder settings and alignment of tension 2. Brackets with drum to be carried out as frequently as possible 40. Formation of ribbon like structure on the circumference of the cone 20 41. EFFECT High level of slough off during unwinding •Excessive yarn waste •Uneven dye pick up in the case of dye packages CAUSES Winding spindle not revolving freely Cone holders incorrectly set Defective settings of cam switch Lint accumulation in builder cam groove RECTIFICATION Over hauling of cone winders to be periodically carried out 1. Anti ribboning mechanism to be checked at frequent interval 2. Free movement of the cone holders to be ensured by proper lubrication 42. Unduly soft structure of cone 21 43. EFFECT Overall density of package is lower •Soft packing either at the base or at the nose of cones CAUSES Improper alignment of winding spindle to the winding drum Insufficient unwinding tension Inadequate cradle loading RECTIFICATION Unwinding tension to be maintained at 6 to 8% of single yarn strength 1. Cradle pressure to be maintained to the optimum level 44. Cones which are tightly built at centre, presents a shape of bell 22 45. EFFECT Excessive breaks during subsequent processes CAUSES High yarn tension during winding Cone holders incorrectly set to the winding drum Damages in paper cone centre RECTIFICATION Quality of cones to be checked at that time of procurement 1. Optimum unwinding tension to be maintained 46. Bulging of bunches of the yarn at the nose of the cones 23 47. EFFECT Slough during warping/unwinding •Excessive yarn waste in next process CAUSES Improper setting of cone holders to the winding drum Damaged nose of the paper cones RECTIFICATION Periodical inspection of settings in winding machines 1. Tenters to be instructed to adopt correct work practices 2. Avoiding usage of damaged paper cones 48. Collapse of the structure of the cone(paper cone)itself 24 49. EFFECT Use of poor quality /damaged paper cones •Poor system of material handling •Maintaining non optimum unwinding tension CAUSES Use of poor quality/damaged cones RECTIFICATION Using of poor quality/damaged paper cones should be avoided 1. Winding tenters should be trained by proper work methods 2. Proper material handling devices such as cone transport trolleys to be used 3. Cone inserts to be used for paper cones 50. Faults: miss-shaped laps. Remedy: •If the censity of cotton across the width of the laps is constant ,wedge shaped laps can still occur due to unequal pressure on side of the calendar r/r. •Pressure should be equal on both sides. Faults: split laps. Remedy: •If lap licking at the card persists, it can be prevented by feeding roving into the lap sheet as it is formed at the lap end or by use of lap r/r.



51. Faults: Poor cleaning efficiency. Remedy: •In the m/c cleaning efficiency is affected by grid bar to beater settings, better speeds, condition of beater blade edges and beater bars, fan speed and m/c cleanliness. •Appropriate stapes have to be taken. Faults: Neps Formation Remedy: •The paddle regulator mechanism and cone drum drive should be kept in good working order. 52. Faults: neppy web. Remedy: • The m/c made neps may be due to an excessive number of immature fibres in the cotton or to poor settings and maintenance. Which should be properly maintained. Raw materials: •Checking that the belts are correctly mixed according to micronaire value and fibre bundle strength. •Percentage of wastage should be maintained accordingly. Faults: cloudy web. Remedy: •Correct settings of back sheet. •Poor condition of wire with patches missing, damaged or rubbed will have the same results which should be maintained. 53. Faults: Irregular sliver. Remedy: •Any eccentric r/r, incorrect undergrid settings, rubber wire across the eccentric r/r settings should be on the points. 54. Faults: fine sliver. Remedy: •All drawframe stop mechanism should be regularly tested. Faults: irregular sliver. Remedy: •Checking top and bottom r/r, top spinning pressure and r/r settings and taking suitable action. •Also checking that sliver is not being reserved. 55. Faults: Neppy waste. Remedy: •Top combs and cylinders should be examined daily because damaged cylinder wire/needles and top com needles can cause flocking. Faults: Long fibers in waste. Remedy: There are a number of comber settings and timings which will cause long fibre to be found in the wastage. They include insufficient of the nippers during feeding, late closing of the nippers, wide detaching r/r settings detaching r/r turning back too late which should be properly observed. 56. Faults: Irregular sliver. Remedy: •R/R, r/r settings and drafts should be checked. Faults: Curls. Remedy: •Correct timing of nippers and detaching r/r, correct penetration of the top combs and r/r covering. 57. Faults: Slippings coils. Remedy: •Attention to finding the correct taper wheel, resetting poker bar and the builder will cure this faults. Faults: Soft bobbins. Remedy: •This faults can be prevented by using suitable change wheels. If an odd bobbin is affected this could be due to fine a fine roving or incorrect tensioning. Faults : Irregular roving. Remedy: •Simplex m/c are susceptible to this faults and source of the vibration is usually in the gearing or grafting r/r. 58. Faults: Count and hank variation Variation in hank and count should be monitored and controlled as previously specified by: •Regular daily inspection and maintained strict control lap weights, weekly meter/metre wrappings of scutcher laps, calculating variation and graphing results. •Wrapping finisher drawframe sliver every 4 hours and taking immediate action if results exceed tolerance quality control graphs to be used. •Daily wrappings of yarn for count, regularity of count, strength and twist. Assessment of yarn on blackboards. •Faults have adequately death with earlier in this section under regularity. 59. Faults: Foreign fibers: Remedy: •Operatives working in the mixing chamber must be instructed to take out any foreign fibers, string, cloth contaminated with dye or oil. •Care have to be taken when taking the tare from the bale. Faults: Twist variation: Remedy: •Too much twist reduces yarn strength and also makes the yarn brittle and liable to from snarls. Spindle to spindle variation also occurs due to differences in spindle speed as a result of driving tape slippage, misalignment of tapes and spindle bearings or inadequate lubrication which should be maintained properly. 60. The quality control in spinning has a vital consequences on the production. In the aspect of textile it is a must to make sure to fulfill the general requirement of the quality in different stages in spinning.



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