Faults in the Knitted Fabrics (part 5)

NeedleLines
Definition:
Needle lines are prominent vertical lines along the length of the fabric which are easily visible in the grey as well as finished fabric. 

 Causes:

• Bent Latches, Needle Hooks & Needle stems
• Wrong Needle selection (Wrong sequence of needles, put in the Cylinder or Dial 
• Remedies:

• Inspect the grey fabric on the knitting machine for any Needle lines.
• Check the Needle filling sequence in the Cylinder / Dial grooves (tricks).

Horizontallines
Causes:

• Fault in bobbin
• Irregular tension on cams. 
• Remedies:

• Replace that bobbin.
• Check cams positioning

BrokenNeedles/ Laddering
Definition:
Defects caused by the broken needles show prominently as vertical lines parallel to the Wales. There are no loops formed in the Wale which has a broken needle.

• High Yarn Tension
• Bad Setting of the Yarn Feeders
• Old & Worn out Needle set
• Cylinder Grooves are too tight restricting needle movement
• Breakage of hook or butt in needle.

Remedies:

• Ensure uniform & the right Yarn tension on all the feeders.
• Keep the recommended gap between the Yarn Feeders & the Needles.
• Periodically change the complete set of needles.
• Remove fly or blockage from groove.
• Replace defective needle.

SinkerLines
Definitions:
Sinker lines are prominent or feeble vertical lines appearing parallel to the Wales along the length of the knitted fabric tube. 

 Causes:

• Bent or Worn out Sinkers
• Sinkers being tight in the Sinker Ring grooves

Remedies:

• Replace all the worn out or bent sinkers causing Sinker lines in the fabric.
• Sinker lines are very fine & feeble vertical lines appearing in the fabric.
• Remove the fibers clogging the Sinker tricks (Groove

OilLines
Definitions:
Oil lines are prominent vertical lines which appear along the length of the knitted fabric tube. The lines become permanent if the needle oil used is not washable & gets baked due to the heat during the finishing of the fabric. 

 Causes:

• Fibers & fluff accumulated in the needle tricks which remain soaked with oil.
• Excessive oiling of the needle beds.

Remedies:

• Fibers accumulated in the needle tricks cause the oil to seep into the Fabric.
• Some lubricating oils are not washable & can not be removed during Scouring.
• Remove all the Needles & the Sinkers of the machine periodically.
• Clean the grooves of the Cylinder & Dial of the machine thoroughly with petrol.
• Blow the grooves of the Cylinder Dial & Sinker ring with dry air after cleaning.

BrokenEnds
Definition:
Broken ends appear as equidistant prominent horizontal lines along the width of the fabric tube when a yarn breaks or is exhausted.

Causes:

• High Yarn Tension
• Yarn exhausted on the Cones.

Remedies:

• Ensure correct yarn tension on all the feeders.
• Ensure that the Yarn detectors on all the feeders are working properly.
• Depute a skilled & alert machine operator on the knitting machine.

Faults in the Knitted Fabrics (part4)

Snarls
Definition:
Snarls appear on the fabric surface in the form of big loops of yarn getting twisted due to the high twist in the yarn.
Causes:

• High twist in the yarn.

Remedies:

• Twist in the yarn should be in required TPM.

Contaminations
Definition:
Contaminations appear in the form of foreign matter such as; dyed fibers, husk, dead fibers etc. in the staple spun yarn or embedded in the knitted fabric structure.
Causes:

• Presence of dead fibers & other foreign materials, such as; dyed fibers, husk & synthetic fibers etc.
• Dyed & other types of fibers flying from the adjacent Knitting machines cling to the yarn being used for knitting & get embedded in the Grey Fabric.

Remedies:

• Use rich fiber mixing for the yarns to be used for Knitting in order to have less dead fibers appearing in the fabric.
• Rigid control measures in the Blow Room to prevent the mixing of foreign matters in the Cotton mixing.
• Segregate the Spinning & Knitting Machines, with Plastic Curtains or Mosquito Nets, to prevent the fibers flying from the neighboring machines, from getting embedded in the yarn / fabric.

Spirality
Definition:
Spirality appears in the form of a twisted garment after washing.The seams on both the sides of the garment displace from their position & appear on the front & back of the garment.

Causes:

• High T.P.I. of the Hosiery Yarn
• Uneven Fabric tension on the Knitting machine.
• Unequal rate of Fabric feed on the Stenter, Calender & Compactor machines.

Remedies:

• Use the Hosiery yarns of the recommended TPM level for Knitting.
• Ensure uniform rate of feed of the dyed fabric on both the edges while feeding the fabric to the Calender, Compactor or Stenter machines.

Faults in the Knitted Fabrics (part 3)

FinishingRelated Defects:
Defects caused mainly due to the wrong process parameters are;

1. High Shrinkage
2. Skewing
3. Spirality
4. Surface Hairiness & Pilling
5. Tonal variation
6. Snagging (Sharp points in the dyeing machine or trolley etc)
7. Fold Marks
8. Wet Squeezer Marks
9. GSM variation
10. Fabric Width variation
11. Curling of S.J. Fabrics

DropStitches (Holes)
Definition:
Drop Stitches are randomly appearing small or big holes of the same or different size which appear as defects in the Knitted fabrics.

Hole in fabric

Major Causes:

• High Yarn Tension
• Yarn Overfeed or Underfeed
• High Fabric Take Down Tension
• Defects like Slubs, Neps, Knots etc.
• Incorrect gap between the Dial & Cylinder rings.

Remedies:

1. Ensure uniform yarn tension on all the feeders with a Tension Meter.
2. Rate of yarn feed should be strictly regulated as per the required Stitch Length.
3. The fabric tube should be just like a fully inflated balloon, not too tight or too slack.
4. The yarn being used should have no imperfections like; Slubs, Neps & big knots etc
5. The gap between the Cylinder & the Dial should be correctly adjusted as per the knitted loop size.

Barriness
Definition:
Barriness defect appears in the Knitted fabric in the form of horizontal stripes of uniform or variable width.

Causes:

• High Yarn Tension
• Count Variation
• Mixing of the yarn lots
• Package hardness variation

Remedies:

• Ensure uniform Yarn Tension on all the feeders.
• The average Count variation in the lot should not be more than + 0.3
• Ensure that the yarn being used for Knitting is of the same Lot .
• Ensure that the hardness of all the yarn packages is uniform using a hardness tester.

Streakiness
Definition:
Streaks in the Knitted fabrics appear as; irregularly spaced & sized, thin horizontal lines.

Causes:

• Faulty winding of the yarn packages.
• Yarn running out of the belt on the Pulley

Remedies:

• Winding of the yarn package should be proper.
• The yarn should be running between the belt and around the pulley.

Imperfections
Definition:
Imperfections appear on the fabric surface in the form of unevenly placed or randomly appearing Knots, Slubs & Neps, Thick & Thin places in the yarn.

Causes:

• Big Knots, Slubs & Neps in the yarn, Thick & Thin yarn.

Remedies:

• Specify the quality parameters of the yarns to be used for production to the yarn supplier.

Faults in the Knitted Fabrics (part 2)

KnittingElements Related Defects:
Almost all the defects appearing in the vertical direction in the knitted fabrics are as a cause of bad Knitting Elements.These defects are mainly;

1. Needle & Sinker Lines
2. Drop Stitches etc.

MachineSettings Related Defects:
These defects appear randomly in the knitted fabrics due to the wrong knitting machine settings &that of the machine parts. The defects are mainly;

1. Drop Stitches
2. Yarn Streaks
3. Barriness
4. Fabric press off
5. Broken Ends
6. Spirality

DyeingRelated Defects:
The Dyeing related defects are as follows;

1. Dyeing patches
2. Softener Marks
3. Shade variation
4. Tonal variation
5. Color fading (Poor Color Fastness)
6. Dull shade
7. Crease or rope Marks