Grey inspection and woven and knitted fabric defects
Grey Inspection & Fabric Defects Aravin Prince Periyasamy Assistant Professor Dept of Textiles, DKTE Textile Engineering Institute Ichalkaranji, Maharashtra, India firstname.lastname@example.org 0091-9790080302
InspectionDefinition:Activities such as Measuring, Examining, Testing, Gauging, one or more characteristics of a product or source comparing these with specific requirements to determine conformity.2
Grey cloth from weaving have many faults ( Broken ends and picks, stains and etc) Many of these faults can be corrected at grey stage before wet processing . Also in grey inspection following points are checked, EPI, PPI, Width and Length of fabric & GSM.
Principles3c’s Of InspectionEvery Inspection Is Involving 3c’s .CheckCompareConclude
Inspection Instruments / Tools The assessment may be carried out usually or by Pick glass Measurement by tape Visual UV lamp Streak analyzer Spotting with Shirley stain or similar staining agents5
Flow Based Fabric Inspection Minor Faults: 1 defects within 15 CM is considered as a minor faults. Major Faults: Within 15 CM More than 1 defects is considered as a Major Defects Selvedge Defects Incase of furnishing fabric minor selvedge defects like pulled in selvedge are considered as major defects Small defects are nearer to the selvedge means, it will not considered to the serious problem.
Point Based Fabric InspectionFabric Inspection: There are Three types…… • 4 Point system • 10 Point system • Mil- Standards8
4 – Point SystemIn ’4 Points’ system of grading, faults are scored with penalty of 1, 2, 3 and 4according to the size and significance Size of Defect Penalty Points Upto 3 inches 1 >3” to 6” inches 2 >6” to 9” inches 3 Above 9 inches 4
Four Point System •Maximum of 4penalty points can be assigned for any single defect - No linear yard / meter can be assigned more than 4 points regardless of number of defects within the yard/meter. •Employing the following criteria: The defects in both wrap/weft, course/wale directions will be assigned points10
10 Point System •In ’10 Points’ system of grading, faults are scored with penalty of 1, 3, 5 and 10 according to the size and significance Size of Defect Penalty Points 1 inches or less 1 Over 1” but not over 5” 3 Over 5” not over 10” 5 Over 10” / full width 10Application
Point count calculation For Individual Roll:Points per 100 Sq. yards = Total linear points x 3600 Length in Yds x Fabric width in inches12
Eg (Calculation) Knitted fabric length is 58 yds, width 60 inch for inspection. Following defects and points can be found (4 –Point Method), Size of Defects Defects Total Points Upto 3 Inch 2 2X1= 2 3- 6 Inch 3 3X2= 6 6 – 9 Inch 2 2X3= 6 More than 9 Inch 1 1X4= 4 Total Points Earned 18 Points Points per 100 Sq. yards = Total linear points x 3600 Length in Yds x Fabric width in inches • Points / 100 Sq Yds = 18 X 3600 • 58 X 60 • Points / 100 Sq Yds = 18.63 • As per the standard less than 40 points / 100 sq yds is considered First Class • As per the standard more than 40 points / 100 sq yds is considered Second Class
Different Color Tags for Different Processes & Defects In export two types of tag used Red tag It represented the critical defects White tag It represented minor defects (add 10 CM of fabric wherever defects is present)
Knitted WovenBarre BarBirdseye Broken endsBroken pattern Broken picksRun Burl marksSkip Stitch Coarse End/PickDropped stitches CrackEnd out FloatMisdrawMissing yarn Fly waste Jerk-in Some CommonMixed Yarn Knots Fabric DefectsNeedle Line Off PatternPress off Reed Mark Slack end Slough off Slub Smash Soiled / Oily FillingProcessing Defects : Bow/Skew, Color Out, Color Smear, Doctor Streak, Dye Stain, Out ofregister, Sanforize pucker, Seam impression, Scrimp
Advantages End of roll automatic stop sensor - For next roll joining This will allow for efficient continuous inspection, from roll to roll. Accurate fabric length and optional weight measurements Fabric roll length and weight can be taken using industrial standard measuring systems with digital readouts to give consistent fabric roll assessments. Auto adjustable tension Automatic adjustable tension of fabric when rewinding. Data collection and analysis system - With fabric fault tagging 100% fabric inspection with simple push-button accurate fault logging, roll length and weight measurement allowing for accurate fabric roll analysis and printout. www.cihanmakina.com
List of fabric defects in woven fabrics Coloured flecks • Missing ends Knots • Missing Pick Slub • Oil and other stain Broken ends woven in a • Oily ends bunch • Oily picks Broken pattern • Reed mark Double end • Slough off Float • Shuttle smash Gout • Snarls Hole, cut, or tear • Stitches Lashing-In • Untrimmed loose threads Local distortion • Weft bar
Coloured Flecks COLOURED FLECKS : Presence of coloured foreign matter in the yarn. CAUSES : Cotton fibres getting contaminated during the ginning stage with leaves, immature fibre, yellow fibre, etc. MENDING: Coloured portion is removed from the yarn with a plucker. The resultant bare patch can be corrected by combing with metallic comb.
Knots Knots : Knot is a fastening made by tying together the ends of yarn. Causes : Thread breaks during process of winding, warping, sizing or weaving. MENDING: Non Mendable.
Slub Slub : Slub is a bunch of yarn having less twist or no twist and has a wider diameter compared to normal spun yarn. Causes : Improper carding/ combing. Broken tooth in the chain of gear system. Mending: The slub should be cut with the clipper from both the ends. The resultant bare patch can be corrected by combing with a metallic comb or by insertion of a separate thread with the help of fine needle.
Broken pattern Broken pattern : A broken pattern is the non continuity of a weave/ design/ pattern. CAUSES : Wrong drawing in of threads. Incorrect shedding. MENDING: Non Mendable.
Broken Ends woven in a bunch Broken ends woven in a bunch : This defect is caused by a bunch of broken ends woven into the fabric. CAUSE : Failure of the weaver in attending the warp breaks properly. MENDING: The broken ends woven in a bunch can be removed by using a plucker and the resulting loose ends should be cut with clipper. As a result, a bare patch occurs and combing in both directions with a metallic comb can fill this up.
Double end Double end : When two or more ends gets woven as one. This defect is characterized by a thick bar running parallel to the warp. CAUSES : Wrong drawing, taking more ends in heald eye. MENDING: This fault can be corrected by pulling out the extra end with the help of needle. A bare patch is formed and can be filled by combing in both directions with the help of metallic comb.
Float Float : Float is the improper interlacement of warp and weft threads over a certain area. CAUSES : Improper sizing (ends sticking). Broken end entangling with the other ends. MENDING: Only minor floats can be rectified. The floating threads are cut with a clipper . Combing in both direction rectifies the resultant patch.
Gout Gout : Gout is a foreign matter accidently woven into the fabric. CAUSES : Improper loom cleaning. Unclean environment. MENDING: The extra foreign matter can be pulled out with a plucker. Combing in both direction rectifies the resultant patch.
Hole, Cut, Tear Hole, Cut or Tear : This is self explanatory. CAUSES : Sharp edges on cloth roll. Hard substance between layers of fabric in cloth roll. Course temples used for fine fabric. During removal of hard particles like, Iron particles woven in the cloth. MENDING: Non mendable.
Missing Ends : The fabric is characterised by a gap, parallel to the warp. The number of ends missing may be one or more.CAUSES : Loom not equipped with warp stop motion. Dirty drop wires or accumulation of lint may prevent their dropping. In electric warp stop motion, the electric bars are dirty or corroded.MENDING: When there are only two adjacent ends missing, the fault can be rectified by combing in both directions using a metallic comb. This may fill the bare patch formed due to missing ends.
Missing Picks Missing Picks : A narrow streak running parallel with weft threads caused due to absense of weft. CAUSES : Faulty let-off and take-up motion. Faulty weft-stop motion. Fell of the cloth not adjusted after loom stoppage for mending. MENDING: When there are only two adjacent picks missing, the fault can be rectified by combing in both directions using a metallic comb. This may fill the bare patch formed due to missing ends.
Untrimmed Loose Threads Untrimmed loose threads : Any hanging threads on the face of the fabrics are termed as loose threads. CAUSE : Tail ends not trimmed after piecing up. MENDING: These defects can be easily rectified with the help of clipper.
Weft Bar Weft bar : An unwanted bar, running across the full width of a piece which differs in appearance from the adjacent normal fabric. CAUSES : Difference in count, twist, colour, lustre. Faulty let-off and take-up motion. MENDING: Non mendable .
Shuttle Smash Shuttle smash : Ruptued cloth structure characterised by many broken warp ends and floating picks. CAUSES : Improper timing. Insufficient picking force. Slack ends in certain portion. The sagging ends obstructs shuttle flight. MENDING: Non mendable.
Lashing in Lashing in : An extra piece of yarn woven into the fabric in the vicinity of the selvedge. CAUSES : Defective setting of the shuttle box. Early or late picking. In case of auto loom, weft cutters worn out or not set properly MENDING: This defect can be corrected by pulling out the extra pick from the selvedge end, which can be clipped with the help of clipper. A bare patch is formed and can be filled by combing in both directions with the help of metallic comb.
Oil Or Other Stain: These are spot defects of oil, rust, grease orother stains found in the fabric.CAUSES : Improper oiling/greasing of looms. Oil stained Take up roller.MENDING:1. Keep the stained portion of the fabric over an absorbent pad. Apply the stain remover, wetting the stain and surrounding portion throughly.2. Rub gently to quicken the penetration of the stain remover.3. Rubbing should be done towards the centre of stain to avoid spreading.4. Note: Delicate fabric needs reduced pressure, otherwise, hole formation or displacement of the fabric will occur.
Oily Ends : These are oily warp ends.CAUSES : Improper handling and storage of material in spinning department. Oil-contaminated guides and oily hands during process of warping. Improper handling of warp beams.MENDING:1) Keep the stained portion of the fabric over an absorbent pad. Apply the stain remover, wetting the stain and surrounding portion throughly.2) Rub gently to quicken the penetration of the stain remover.3) Rubbing should be done towards the centre of stain to avoid spreading. Note: Delicate fabric needs reduced pressure, otherwise, hole formation or displacement of the fabric will occur.
Oily weft : These are oily weft picks.CAUSES : Improper handling and storing in spinning department. Weft package falling on oily ground. Handling the weft with oily hands. Weft carring baskets having oil. Dropping of oil on weft package during oiling of the winding machine.MENDING:1) Keep the stained portion of the fabric over an absorbent pad. Apply the stain remover, wetting the stain and surrounding portion throughly.2) Rub gently to quicken the penetration of the stain remover.3) Rubbing should be done towards the centre of stain to avoid spreading. Note: Delicate fabric needs reduced pressure, otherwise, hole formation or displacement of the fabric will occur.
Local distortion : A Distortion occurs when there is displacement ofwarp and/or weft threads from their normal position.CAUSES : The emery roll is worn out. In filament fabric having low reed picks.MENDING: This defect can be corrected by combing in bothdirections using a mettalic comb.
Broken pattern due to defective piles : A broken pattern isthe result of non-continuity of the design/pattern in the pilefabric.CAUSES : Improper working of terry motion on loom. Improper functioning of jacquard. Missing pick.MENDING: Non mendable.
Uneven or loose piles : In this type of defect there is variation in the pile height over the surface of the fabric. CAUSES : Improper working of terry motion on loom. Improper functioning of jacquard. Missing pick. MENDING: Non Mendable.
List of fabric defects in Knitted fabrics Bariness Bunching up Drop stitch Holes or Crack Crack fall out Horizontal srtipes Verticle stripes
Bariness : A fabric defect characterized bytextural bands or color bands in the coursedirection of a weft knitted fabric.CAUSES : Use of irregular yarn having higher long termirregularities. Using different count thread.MENDING: Non Mendable.
Drop stitch: Local column of dropped stitches. CAUSES : Yarn guide not set poroperly (i.e yarn is not fed properly during loop formation). Defective latch needle. yarn tension is not sufficient. Take-down is too high. Wrong yarn threading. MENDING: This fault can be corrected by stitches reforming using a simple needle. CAN BE AVOIDED BY: Precise yarn-guide setting. Needle change. Dial position readjustment. Use of fabric fault detector.
Holes or crack : Local holes obtained when yarn breaks during loop formation. CAUSES : Relation between cylinder and dial loop not correct. Weak places in yarn, Which breaks during loop formation Knots. Yarn running tension is too high. CAN BE AVOIDED BY : Use of flat knots. Accurate yarn guide setting. Use of fabric fault detector. Use of yarn having lower hariness.
Horizontal stripes : Are caused by uneveness in the courses. They traverse horizontally and repeat themselves regularly or irregularly. CAUSES : Yarn feeder set badly. Differences in the yarn running-in tension. Jerky impulse from fabric take up . Mending : Non mendable.
Verticle stripes : They can be observed as longitudnal gaps in the fabric. The space between adjacent wales is irregular. CAUSES : Bent needles. Heavily running needles. Damaged latch needle. Damaged needle hook. Damaged dial or cylinder. CAN BE AVOIDED BY : Needles and sinkers change after long time use. Use of fabric fault detector.