KNITTING INTRODUCTION AND DEFECTS

1. Prepared by
Rasmin Thahani Z,
Assistant Professor,
Syed Ammal Arts and Science College,
Ramanathapuram.
TEXTILE SCIENCE
KNITTING AND ITS DEFECTS

2. KNITTING
• Knitting is a technique of fabric formation
from yarn.
• Knitting is the art of construction in fabric
by intermeshing the yarn loops.
• A loop within a loop by some knitting
elements.

3. Comparison between Woven
Fabric and Knitted Fabric

4. Woven Fabric Knitted Fabric
Generally coarser count is used. All types of counts can be used.
Moisture absorbency is more. Moisture absorbency is less.
Crease resistance is high. Crease resistance is less.
Fabric is thicker. Fabric is thin.
No wrinkles is formed. Ironing not
required.
Required ironing.
Knitted fabric has good extensibility. Extensibility has less.
Pleat sharpness is less. Pleat sharpness is high.

5. Woven Fabric Knitted Fabric
More permeability to air. Less permeability to air.
Less stronger fabrics. More stronger fabrics.
Any small defects occur in fabric, it
leads to more damage in cloth because
it cannot be mended easily.
No such problems.

6. Classification of Knitted Fabrics
Knitted
Fabrics
Weft Knitting
Plain Knit
Rib Knit
Interlock
Warp Knitting
Tricot Knit
Raschel Knit
Ketten Raschel Knit
Milanese Knit
Jacquard
Knitting
Pile Knit
Pile Knit
Fleece Knit
Terry Knit
Velour Knit
High Pile Knit

7. Important terms in Knitting
• Course:
Series of loops that intermeshes horizontally
in a fabric is called course. Course determines
the length of the fabric and measured in course
per inch.

8. Important terms in Knitting
• Wales:
Series of loops that intermeshes vertically in
a fabric is called as Wales. Wales determines the
width of the fabric and measured as Wales per
inch.

9. Types of loops
• Elements of knitting loop structure.
• Loop consists of two parts:
1. Sinker loop
2. Needle loop
• This two loops are simply known as knit loop.

10. Needle Loop
• A loop in a knitted fabric which
has been drawn through a
previous loops by a needle.
• The needle loop is the
simplest unit of knitted structure.
• Needle loop is the top portion of each loop.

11. Sinker Loop
• A loop that connects two adjacent needle loops,
a bottom portion ‘U’ shape is called as sinker
loop.

12. Face loop
• When a loop is drawn from
the back of the previous loop
to the front of the fabric is
called as face loop.

13. Back loop
• When a loop is drawn
from the face of the previous
loop to the back of the
fabric is called as back loop.

14. Stitch Length or Loop Length
• The length of the yarn associated with a loop is
called loop length.

15. Identification of
Knitted Fabric
Defects

16. Yarn related defects:
Almost all the defects appearing in horizontal direction in the
knitted fabric are yarn related defects.
The defects are:
• Barriness
• Thick and thin lines
• Dark or light horizontal line (due to the difference in dye pick
up)
• Imperfection
• Contamination
• Snarling
• Spirality

17. Knitted Element related defects:
Almost all the defects appearing in vertical line
direction. Knitted fabrics are as a cause of bad
knitting elements.
The defects are:
• Needle & Sinker line
• Drop stitches

18. Machine Setting Element related
defects:
These defects appear randomly in the knitted fabric
due to the wrong knitted machine setting and that of
machine parts.
The defects are:
• Drop stitches
• Yarn sleaks
• Barriness
• Fabric Press Off

19. Dyeing related defects:
The defects are:
• Dyeing Patches
• Shade variation
• Colour fasting
• Dull shades
• Crease or rope marks

20. Finishing related defects:
The defects are:
• High shrinkage
• Spirality
• Face hairiness & pilling
• Fold marks
• GSM Variation

21. Some Common
Knitted Fabric
Defects

22. Drop Stitches (Holes):
• Drop stitches are randomly appearing small or big holes of the same or
different size which appear as defects in the knitted fabric.
Causes:
• High yarn tension
• Yarn overfeed or under feed
• Defects like slubs, neps and knot, etc.
• Incorrect gap between the dial and rings.
Remedies:
• Ensure yarn tension on all the defects with a tension meter.
• Rate of yarn feed should be strictly regulated as per the stitch length.
• The yarn being used have no imperfection like slubs, neps and big knot, etc.
• The gap between the cylinder and dial should be correctly adjusted as per
the knitted loop size.

23. Barriness:
• Barriness defects appear in the knitted fabric in the form of
horizontal stripes of uniform variable width.
Causes:
• High yarn tension
• Count variation
• Mixing of the yarn lots
Remedies:
• Ensure uniform yarn tension on all the feeders.
• The average count variation in the lot.
• Ensure the yarn being used for knitting in the same lot.

24. Imperfection:
• Imperfection appear on the fabric surface in the
form of unevenly placed or randomly appeared
knots. Slubs & neps thick & thin places in the yarn.
Causes:
• Big knots, slubs & neps in the
yarn, thick and thin yarns.
Remedies:
• Specific the quality parameters of the yarn to be
used for production to the yarn supplier.

25. Spirality:
• Spirality appears in the forms of a twisted garment after washing. The
seams on both sides of the garment displace from their position and appear
on the front and back of the garment.
Causes:
• High TPI of the hosiery yarn.
• Uneven fabric tension on the knitting
machine.
• Overall rate of the fabric feed on the
slenter, calender compactor machine.
Remedies:
• Use the hosiery yarn to 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 slenter machine.

26. Broken Needles:
• Defects caused by the broken needles show prominently a
vertical line parallel to the Wales. There are no loops formed
in the wale which has a broken needle.
Causes:
• High yarn tension
• Bad setting of the yarn feeder
• Old and worn out needle set.
Remedies:
• Ensure uniform and the right yarn tension on all the feeders.
• Keep the recommended gab between the yarn feeders and the
needles.
• Periodically change the complete set of needles.

27. Sinker Lines:
• Sinker lines are prominent and vertical line appearing parallel
to the Wales along the length of the knitted fabric.
Causes:
• Bent or worn out sinkers
• Sinker being tight in the sinker ring
Remedies:
• Replace all the worn out or bent sinkers
causing sinker lines in the fabric.
• Sinker lines are very fine and feed vertical line appear in the
fabric.

28. Needle Lines:
• Needle lines are prominent vertical line along the length of the
knitted fabric which are easily visible in the grey as well as finished
fabric.
Causes:
• Bent latches
• Needle hooks
• Needle stamps
• Wrong needle selection, wrong sequence of needle put in the
cylinder or dial.
Remedies:
• Inspect the grey fabric on the knitting machine for any needle lines
• Check the needle fitting sequence in the cylinder or dial grooves.

29. Oil Stains:
• Stains appear as spots or patches of grease, oil or dyes of
different colour, in a neat & clean finished fabric surface.
Causes:
• Crease and oil stains from the
un guarded moving machine parts like
gears, trolley wheels, etc.
• Fabric touching the floor and other
soiled places during transportation in the trolleys.
Remedies:
• Make sure that the fabric is neatly packed or in covered with
polythene sheets, while transporting or in storage.

30. Snarls:
• 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
• Hosiery yarns are soft twisted.
• High twist in the yarn, is the
cause of snarling
• Snarls cause fabric defects &
needle breakages
Remedies:
• Ensure using hosiery yarns of the recommended TPM only
• The yarn has a balanced twist, if it doesn’t tend to rotate or turn, in
the form of a snarl.

31. Contamination:
• 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 the foreign materials,
in the staple fiber mixing.
• 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.