Different ways of fabric dyeing with different dyestuffsFull description
FABRIC SCIENCE
Fabric defects are identified during the grey inspection of the fabric after weaving or knitting. These defects are classified into three groups
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Avoidable and unavoidable Major and minor Mendable and unmendable
While most of the defects in the fabric are avoidable some are unavoidable such as certain floats/smashes. Defect such as weft crack is considered to be a minor if it is within 1-2 cm while the same defect is major when it is more than 2cm. Certain defects such as isolated snarls could be mended while the others such as big cracks are unmendable.
BAR
A general terms for a band running across the full width of the cloth due to difference in the appearance from its adjacent sites. It covers ◦
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Pick bar, Starting Mark, Tension bar or shiner and Weft bar
BOX MARK A widthwise line showing stained or injured weft due to the rubbing of shuttle when rebound. BROKEN PATTERN This defect may be due to wrong drawing of thread, inserting a pick in the wrong shed, incorrect lifting of warp thread. BROKEN PICK A pick missing from a portion of the width of the fabric due to rough shuttle-eyes which snag the weft.
CRACKES A narrow streak running parallel to the weft due to pronounced opening between to adjacent yarns caused due to the erratic operation of the sley. CUT WEFT A pinhole in the finished fabric caused by the use of weak weft with a strong warp. FLOATS STITCHES A place in the fabric where warp and weft yarns escape the required interlacement due to entanglement of warp threads.
FUZZY Fibrous appearance of the cloth due to the presence of abraded yarns. HANG PICK A pick which is out of line for a short distance producing a triangular shaped hole in a fabric. HARNESS(WARP) SKIP Warp yarns appearing more or less continuously on the surface of the fabric due to non interlacement of weft yarns.
LASHING IN Also known as weft trail or jark in weft it is caused by an extra yarn dragged into the cloth along with the regular pick. LOOSE WARP ENDS Loose warp ends which appear like a reed mark are caused by loose ends which start to feed in just a trifle faster than the rest of the warp. HANGING THREADS Ends loose on the face of the fabric because the short and long ends of the fabric are not removed by the weaver.
MISSING ENDS The most common defect characterized by a gap of one or more warp threads in a fabric caused due to unmended broken ends, missing ends and high incidence of warp breakages. REED MARKS A ready cloth shows irregular spacing between groups of warp yarns across the width of the fabric caused by a damaged or defective reed or too late reed shedding.
SHUTTLE MARKS Widthwise warp yarns due to abrasion of warp yarns by shuttle. SLOUGH-OFF Bulk of weft yarns which slips off the pirn and get entangled into fabric caused due the loose winding of pirn.
STICKER A distortion in a weave characterized by tight and slack places in the same warp yarn or fabric. STAINS Stains such as grease, rust etc occur due to poor material handling.
TEAR DROPS Appearing in taffeta fabrics as short curved picks caused due to insufficient warp tension, incorrect heald timing, oversized warp and uneven penetration of sizing solution etc. TEMPLE MARK holes or surface disturbances along the selvage of the fabric. Due to bad or improperly adjusted temples.
UNEVEN CLOTH Inconsistent diameters of the weft produces a shady cloth where principle of weft mixing is not used.
WRONG DENTING/DRAWING The wrong order of drawing ends through healds and reeds respectively also creates fabric defects.
DEFECTIVE SELVEDGE ◦
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Curled selvedge: Caused due to incorrect balance of cloth structure between body and selvedge. Cut,torn or burst selvage: Caused due to selvedge sticking to emery roller or damages caused by temple roller. Loppy selvedge: Caused when the selvedge or cut the race board felt at the reed and the weft is caught on this groove when the sley s ley beats up. Pulled in selvedge: Caused due to isolated tight picks.
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Rugged or ragged selvedge: Caused due to the variations in tension of the selvedge ends. Slacked selvedge: Caused due the incorrect balance of cloth structure between the body and the selvedge. Tight selvedge: Caused due to incorrect balance of structure between body and selvedge,selvedge yarns woven at high tension. Uneven selvedge: Caused by the variation in weft tension, lack of control on number of selvedge ends.
The methods employed for analysis of fabric defects are
1. Firs Firstt pi piec ece e in insp spec ecti tion on 2. Grey inspection 3. Point rate sy system
The first piece of the newly gated loom is taken to the grey floding departments and is inspected fir design verifications. The report is immediately sent to the weaving department and if there is any defect the the neccesary changes are made.
Fabrics are tested in grey state after weaving and then after finishing processes. In the grey inspection the fabric defects are identified and mended if they are mendable. In the final folding the fabric defects are examined and graded into the following six categories depending upon severity of faults:
1. Fresh or first quality: fabric with no major or objectionable faults. 2. Shorter length: piece of cloth having shorter length(less than 50 cm). 3. Seconds: cloth having minor defects. 4. Fents : The cut pieces of cloths measuring 90cm and more but less than 150 cm in length are graded as fents. 5. Rags : The cut pieces of cloths larger than 25cm but less than 90 cm are regarded as rags. 6. Chindies : These are the cloths having length of 25 cm or less.
The two most commonly used point rate systems are
4-point rate system 10-point rate system.
4-point system Given by American standard ASTM,the test method describes a procedure to establish a numerical designation for grading of fabrics from a visual inspection. This system does not establish a quality level for a given product, but rather provides a means of defining defects according to their severity by assigning demerit point values.
DEFECT DEMERIT POINT
Length of defect 3 inches or less 3 - 6 inches 6 - 9 inches 9 inches
Demerit Points 1 2 3 4
Points to be remembered while using 4point system are: 1. No running yard shall be penalized more than 4 points for warp and weft defects.
2. For Fabric width exceeding 64"-66", Maximum penalty points can be increased above 4 per linear yard in proportion to the width. 3. Defects appearing within one inch of either edge shall be disregarded. 4. Any hole other than a pin hole shall be considered a major defect and assigned 4 points for penalty.
Grading: 1. Linear Yard basis: Acceptable tolerance=20 points per 100 linear yard 2. Square yard basis: Points/100 sq. yd = Total Points scored in the bulk X 100 X36 Width of the roll(inch) X total yards inspected
10-point system In this system the cloth defects are given demerit points from 1 to 10 depending upon the variety of defect. Warp way defect ◦
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Defects
Penalty points
25cm-90cm
10
12.6cm-25cm
5
2-6cm-12.5cm
3
Up to 2.5 cm
1
Weft way defects Defect
Penalty points
Defects Defects running running full width width 10
Defects 12.5 cm-half width
5
2.6 - 12.5cm
3
Up to 2.5 cm
1
Points to be taken care for 10-point grading are: Not one metre of cloth is penalized more than 10 points even the defect is a combination of warp and weft threads. Any defect occurring repeatedly throughout is marked as second.
Grading of cloth, that is first and second quality depends upon the number of penalty points per piece. Cloth is inspected on the face side only unless specified.
Weaving by Dr.M.K.Talukdar,Prof.P.K.Sriramulu, Prof D.B.Ajgaonkar. Fabric Science by J.Pizzuto
