- 1 Weft Way Defects
- 2 Other Fabric Defects
The fabric defects which are in the direction of weft or caused by the weft are called as weft way defects.
Fabric defect is nothing but a undesirable fault in the fabric which deteriorate the quality fabric and make it inferior.
As you might have read our first post on fabric defects causes and remedies – (Read) Warp Way Defect. This is our another related post on fabric defects causes and remedies – Weft Way Defects.
Weft Way Defects
A defect generally randomly distributed over the fabric, not clearly visible in the gray stage, but becomes pronounced in the finished fabric.
- Improper condition or quality of emery roller covering.
- Viscose yarn from an old lot or of lower strength is used.
- Check the emery roller covering.
- Ensure proper check on the quality of blended yarn.
An abnormal thick place in the yarn finally appearing in the fabric.
- The undrafted portion in the yarn.
- Minimize the incidence of slubs during spinning.
- Clear the yarn effectively during winding.
Restricted to fabric woven with the pattern on drop box looms. It occurs either when the sequence of weft colors to be put is disturbed or when the width of the color band is affected.
- Improper adjustment of pattern cards or lattices.
- Weaver neglecting to adjust the pattern chain before restarting the loom after mending a break or a crack.
- Inserting pick in a wrong shed after mending a weft break.
- Check and adjust pattern cards or lattices.
- Make the weaver’s quality conscious.
- Resort to pick finding prior to restarting the loom.
The weft is inserted only for a portion of a pick.
- Weft break or weft exhaustion on ordinary looms.
- Weft break or improper size of the bunch on auto-pirns.
- The improper functioning of weft fork.
- Weft change effected through weft fork mechanism on automatic looms.
- Check the shuttle for lose fitting of pirn or roughness of the surface as these cause more weft breaks.
- ensure also the shuttle boxes for settings and surface condition to prevent cutting of weft.
- Check the shuttle and shuttle boxes.
- Ensure proper size of the bunch on auto-pirns.
- Maintain the weft fork mechanism in good working condition.
- Resort to pirn change by weft feeler
- Resort also to pick finding before restarting the loom.
Two or more picks inserted in the same shed where only one is desired
- Failure of the weaver to find out the correct shed when restarting an ordinary loom.
- Pirn change when affected by weft fork on automatic loom
- Resort to pick finding while restarting.
- Effect the pirn change with weft feeler mechanism.
Foreign matters like lint or waste or pieces of harness strapping and leather accessories woven into the fabric.
- Indiscriminate throwing of waste by weavers.
- Foreign matter getting into the shed during weaving.
- Ensure cleanliness of machines and surroundings in the loom shed.
- Keep frequent check on harness strappings and leather accessories for undue wear and replace them, if necessary.
Thick bunches of yarn are woven into fabric in the weft direction due to slipping off of coils of yarns from the pirn during weaving.
- Improper package characteristics.
- Softly wound pirns.
- Harsh picking and/or poor shuttle checking.
- Poor humidity conditions during the storage of pirns.
- Employ correct package characteristics in pirn winding.
- Ensure proper yarn tension during pirn winding in the case of rewound weft and in spinning in the case of direct weft.
- Check the picking and checking mechanisms.
- Condition the weft before putting it on loom.
It is a short length of yarn, mostly weft, which has spontaneously doubled back on itself. The snarling tendency is latent in highly twisted yarns. In some fabrics, the snarls are found to be randomly spread over the width of the fabric, while in some other cases, they are restricted to a region at a fixed distance from one of the selvaged.
- Highly twisted weft.
- Low weft tension.
- Shuttle rebounding either due to harsh picking or poor checking.
- Centre weft fork not set right.
- Condition the weft prior to weaving by steam conditioning , CMC conditioning or gumming.
- Provide suitable drag in the shuttle.
- Ensure smooth picking and adequate checking of shuttle in the boxes.
- Check the setting of centre weft fork.
A thick or thin place is produced in the fabric due to variation in pick density while starting the loom.
- Weaver letting back the fell of the fabric too close to the reed by faulty adjustment of take-up motion.
- Faulty functioning of anti-crack motion.
- Instruct the weavers about the correct procedure.
- Ensure correct functioning of the motion.
A higher pick density than the normal is referred to as starting mark while a lower pick density is referred to as crack.
- Improper letting back of the fell of the fabric.
- Improper lifting of the dead weights on let-off motion while adjusting the warp tension.
- Faulty functioning of anti-crack and weft fork mechanisms.
- Snagging of warp due to the shed being kept open for exceptionally long periods.
- Undrafted portion in the yarn.
- Guide the weavers about the right adjustment.
- Set the mechanism properly.
- Stop the looms at healds leveled position so as to ensure minimum of warp tension during the stoppages.
Thick & thin places
Weft bars differing in appearance and repeating several times along the fabric.
- Irregular let-off.
- Faulty take-up.
- Set the let-off and/or take-up motion properly.
Weft way bands which are clearly distinguished from the rest of the portion of the fabric. The bars may be restricted for a particular length of fabric or may repeat at fixed intervals.
- Periodic count variation in the weft yarn arising out of roller eccentricity or mechanical defects in the spinning preparatory processes.
- Mixing of weft of – different counts, different twist levels, different directions of doubling twist and different brightness levels especially in filaments.
- Mixing of spun blended yarns produce from synthetic fibres of different merge numbers.
- Manufacturing defect in filaments like variation in denier.
- Ascertain and rectify the source of periodic count variation.
- Take due care to avoid mix-up of weft during pirn winding and/or weaving.
- Resort to segregation of packages in weft preparation.
- Conduct a dyeing trail on a few pieces before taking up bulk dyeing.
Weft floating on one side
- Shedding either uneven or tilted on one side when connecting band is broken.
- Too weak a picking force from one end leading to passage of shuttle after the shed is crossed.
- Correct the shedding.
- Correct the picking force.
Wrong pick density
- Wrong pick wheel fixed in the take-up mechanism due to carelessness of line jobber.
- Coarser of fine weft used by mistake.
- Ensure strict supervision on pick density at the start of a beam.
- Take precautionary measures.
Other Fabric Defects
Hole or tear in fabric
A defective portion in the fabric marked by distortion or cutting of warp and weft.
- Mechanical faults in loom.
- Weavers tapping the fabric with the shuttle tip or pirn on the front rest when inserting a new pirn.
- Carelessness of the weaver in removing gout.
- Holes from during the finishing processes due to the presence of foreign matter.
- Rectify the mechanism faults.
- Make the weaver quality conscious.
- Take precautions in weaving to avoid incidence of woven foreign matter.
A damaged spot in the fabric with many broken ends and floating picks due to shuttle being trapped in the shed.
- Incorrect timing of shedding and picking.
- Improper starting of loom.
- Too weak or too harsh checking of shuttle.
- Improper working of loose reed and knock-off mechanisms.
- Tune the loom properly.
- check the checking mechanism.
- setting the mechanism properly.
Small pin holes appearing near the selvage zones and being more prominent in fine and superfine varieties.
- Incorrect selection of temples.
- Improper setting of temple cap.
- Temple rings not moving freely.
- Select the temples to suit the quality of fabric.
- Ensure that the cap is not set too close to the temple and that there is sufficient gap for smooth passage of fabric over the temples.
- Ensure cleanliness of temple assembly.
This was our post on Fabric Defects – Weft Way Defects-Causes And Remedies in fabric defects causes and remedies & do read about Fabric Defects – Warp Way Defects Their Causes & Remedies.