Different types of faults in knitted fabrics

In textile industries various common faults in knitting fabrics, which occur during the process. The defects as stated in the foregoing in particular occur during knitting and observed in grey knitted fabrics.

 

 

Causes of faults and their avoidance:
  • When faults occur after using a different material, the need not be traced back exclusively to this material.
  • A faultless state of the knitting machine and optimum machine setting for each material and each knitting structure are, in addition to faultless yarns, avoidance  prerequisites for preventing faults occurring during knitting
Name of the fault:
  • Holes
  • Drop stitches
  • Vertical stripe
  • Horizontal stripe
  • Distorted stitches
  • press-off
  • Bursting
  • Off pattern
  • Bias/Skew•
  • Soiling
  • Oil stains
  • Big knots, slubs
  • Motes & foreign matters•
  • Snagging
  • Color fly
  • Winder line
  • Cloth-fall out

Holes:

The large hole could be due to a weak place inside the yarn leading the yarn to give way or break during loop formation. Small hollow is frequently the end result of a damaged yarn before a knot or splice, for the reason that yarn give up with the knot sits tightly in the ultimate stitch

normally the yarn breaks before the knot or splice, , due to the fact this gets stuck in the needle or gives upward push to a tension peak .only one the loose yarn end can slide out of the loops and the hole can be formed only on one side. The tension is too excessive in relation to the structure and the breaking strength of the yarn.

hole image .what is hole image

Hole

Hole possible causes:

  • Weak place in yarn.
  • Yarn with knots, slubs etc.
  • Very high speed of the machine
  • Needles too tight in the tricks
  • Higher yarn/fabric tension
  • yarn is very dry.

Drop stitches:

Drop Stitch is the end result of a faulty needle. They also occur when a yarn is not well fed during loop formation no longer nicely laid inside the hooks of the needles. The yarn is too stilt and jump away from the needle hooks while being laid-in this could be compensated by a  readjustment of the yarn feeder or by increasing yarn tension. Yarn tension is not sufficient.

Especially with a jacquard system with irregular yarn consumption and jerky processing, the yarn can shoot beforehand and puff itself up among yarn feeder and needle in such a way that it can’t be caught by way of the needle hook. The required tension compensation must take place as close as possible to the knitting zone. The yarn feeder is well-set .the structure or the pattern has not been properly conceived thus isn’t viable to maintain the same take-off tension on all loops for the types used.

what is drop stitch. drop stitch image

Drop Stitch

Vertical stripe :

Vertical stripe may be observed as longitudinal gaps inside fabric .the space between adjoining wales in irregular and the closed appearance of the fabric is damaged in an unsightly manner. Yarn count decided on is too pleasant for the machine gauge or the stitch size (course density) is not correct. Needles are bent, damaged, do not move uniformly smooth, come from different suppliers, or are one-of-a-kind constructed.

what is vertical stripe .vertical image

Vertical stripe

Vertical stripe possible causes:

  • Mix in go of needles/sinkers of different type
  • Bent needles
  • Damage needle latch
  • Damage on other knitting equipment

Horizontal stripe:

Horizontal stripe may be caused to the same extent by the yarn or by the setting of the knitting machine. They do not seem that often with worsted wool yarns. Yarn tension and its fluctuation or a hindrance in yarn delivery is frequent reasons. The setting old stitch size and uniform yarn consumption on feeders with similar settings are essential pre-requesting. The machine should be established horizontally. Needle dia or cylinder should be exactly centered towards.

what is the Horizontal stripe ,Horizontal stripe image

Horizontal stripe

Horizontal stripe possible causes:
  • Uneven yarn
  • Uneven yarn input tension
  • Yarn feeder badly set
  • Mixed yarn
  • Loose stitch cam
  • Uneven twist in the yarn
  • The poor unwinding of yarn

Cloth-fall out:

Cloth falls out is an area that includes. drop stitches lying side by side. They can occur either when a yarn is laid-out or when it breaks without any instantaneous connection. Cloth falls out can occur after a drop-stitch mainly when an empty needle with closed latch runs into the yarn feeder and eliminates the yarn out of the hooks of the following needles.

what is Cloth-fall out.Cloth-fall out image.

Cloth-fall out

Distorted stitches:

Such stitch are usually the result of a bad knitting machine setting, particularly unequal courier depths among dia and cylinder needles. If one views the wales one can then observe that the heads of the stitch are not round .the also appear to have tiled towards the one or the opposite side.

Distorted Stitches possible causes:
  • Bad or bent needles
  • Incorrect positive feed setting
  • Uneven yarn input tension
  • Bent trick wall
  • Wrong stitch cam setting
  • High twist(torque) in yarn

Snags:

Snags occur almost without exception most effective whilst processing contours filament yarn. Besides the precise sensitivity of these yarn. One foremost cause is the mechanical strain for the duration of knitting .filament has been pulled out of the fabric even after knitting some snags may appear mainly in the during fabric setting. During knitting all mechanical influences caused by rough surface on yarn guide elements, yarn feeder, needles fabric take up .etc. should be avoided.

Truck and double stitches:

 Truck or double stitches occur because of badly knitting or non-knitting loops. At first example they also seem as a shadow when the fabric is discovered towards the light. The set dia set is set too high. The needles do not support the fabric, which is, therefore, pulled up.

Colour Fly :

Colour fly consists of single fibers, bunches of fibers or yarn pieces varying colors. it moreover sticks at the yarn or is knitted into the fabric and is very difficult t or removes. Fly coming from numerous processing at some stage in spinning. it can only be avoided by careful separation of individual colors during

Hairs with natural dark colors, vegetables, and food remnants, bast, etc. . or similar natural remnants in these objects are unavoidable and ought to be tolerated.

press-off possible causes :
  • Faulty stop motion
  • Yarn quality is poor
  • Plugged yarn guide
  • Machine running fast
  • Weak knot sand slubs
Bursting possible causes:
  • Too tight fabric
  • Stiff needle latch
  • Uneven yarn input tension
Barre possible causes :
  • Uneven yarn input tension
  • Defective yarn
  • Improper needle action
Off pattern possible causes:
  • Defects in design elements
  • Incorrect feeding arrangement
Bias/Skew possible causes:
  • Uneven take-download
  • Mixed yarn.
Big knots, subs, etc. possible causes:
  • Bad yarn quality 
Motes & foreign matters possible causes :
  • Poor yarn quality.

References:

Circular knitting  

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