Common Defects In Denim Jeans Sewing

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denim-seam-inequalitiesAmerican and Efird – has listed out some of the most common seam inequalities in the manufacturing of denim jeans . The company lists out the defects and suggests solutions for removing these defects. We are summarizing the results from A & E  below :

 

1.BROKEN STITCHES – NEEDLE CUTTING

Description : Where the thread is being broken where one seam crosses another seam (ex: bartacks on top of waistband stitching, seatseam on top of riser seam ) resulting in stitch failure.

denim stiching

jeans sewing

Recommended solution by A & E :

  • Use a larger diameter thread on operations
    where the thread is being cut.
  • Make sure the proper stitch balance is being used. On a chainstitch seam on denim, you normally would like to maintain a 60%/40%
    relationship of Needle thread to Looper thread in the
    Seam.
  • Use needles with the correct needle point.
  • Change the needles at regular intervals on operations
    where the Needle Cuts are occurring frequently.
  • Use a higher performance  Perma Core or D-Core thread.

2.Broken Stitch – Abrasion :

Description : where the thread is broken during stone-washing, sand blasting, hand sanding, etc.  Broken stitches must be repaired by restitching over the top of the stitch-line.

denim defects denim sewing

Recommended Solution :

  • Use a larger diameter thread on operations where
    excessive abrasion is occuring  (ex: use T-120 on
    Waistband
    );
  • Make sure stitches are balanced properly.
  • Use a Magic air entangled thread in the looper due to its lower
    seam profile making it susceptible to abrasion
    (ex: use T-90 or T-135 Magic in loopers of the Yoke, Seat
    and Waistband seam);
  • Monitor the Finishing Cycle for compliance to specs.

3. Broken Stitches : Chemical Degradation :

image

Description : where thread is  being compromised by the chemicals used during laundering resulting in loss or change of color and seam failure.

  • It is recommended to go to larger thread sizes when the
    Denim Garments will be subject to Harsh Chemical
    washes.
  • To achieve the best laundering results make
    sure that the water temperatures and PH Levels are
    correct and that the proper amounts and sequence of
    chemical dispersion are within guidelines.
  • Make sure the garments are being rinsed properly to neutralize the
    chemicals in the fabric.
  • Monitor the drying process, cycle times, and temperatures to make sure they are correct so that the best possible garment quality can be
    achieved.

4. Unravelling Seams :

denim sewing denim stitching

Description : where either the stitch has been broken or a skipped stitch has
occurred. This will cause seam failure unless the seam is Restitched.

Recommended Solution :

  • This may include going to a higher
    performance thread designed to minimize sewing
    interruptions.
  • Observe sewing operators for correct
    material handling techniques.

6. Sagging or Rolling Pockets :

Description :  where the pocket does not lay  SAGGING OR ROLLING POCKETS  flat and rolls over after laundering.

denim stitching

Recommended Solution :

  • Make sure the sewing operators are not holding POCKETS
    back
    excessively when setting the front pocket.
  • Make sure the hem is formed properly and that excessive
    fabric is not being being put into the folder
    that will cause
    the hem to roll over.
  • Check to make sure pocket is cut properly and that pocket curve is not too deep.
  • Use a reinforcement tape on the inside of the pocket that may
    help prevent the front panel from stretching along the bias
    where the front pocket is set.
  • The type and weight of denim, along with the fabric construction, may contribute to this problem. Contact your fabric supplier for assistance.

 

5.Skipped Stitches

Description: where the stitch forming device misses the
needle loop or the needle misses the looper loop. Skips are usually
found where one seam crosses another seam and most of the time
occurs right before or right after the heavy thickness.

denim stiching jeans stiching

Recommended Solution :-

  • Use corespun thread.
  • Use minimum thread tension to get a balanced stitch.
  • Use the ideal foot, feed and plate that helps to minimize
    flagging.
  • Training sewing operators NOT to stop on the
    thickness.
  • Make sure the machine is feeding properly
    without stalling.
  • Make sure the machine is not back-feeding.

6. Ragged – Inconsistent Edge

Description : where the edge of the seam is
either extremely “ragged” or “rolls” inside the stitch.

jeans edge

Recommended Solution :

  • Make  sure the sewing machine knives are sharpened and
    changed often.
  • The knives should be adjusted properly in relationship to the “stitch tongue” on the needle plate to obtain the proper seam width or width bite.

7. Wavy Seams On Stretch Denim

Description : where the seam does not lay  flat and is wavy due to the fabric stretching as it was sewn or during subsequent laundering and handling operation.

image

Recommended Solution : 

  • Use minimum presser foot pressure.
  • Instruct sewing operators to use proper handling techniques and not
    stretch the fabric as they are making the seam.
  • Where available, use differential feed to compensate for the
    stretch of the fabric.

8. Ropy Hem

Description: is where hem is not laying flat and is skewed in  ROPY HEM
appearance .

image

Recommended Solutions :

  • Instruct the sewing operator to make sure they get the hem started correctly in the folder before they start sewing.
  • Also, make sure the don’t hold back
    excessively as the seam is being sewn.
  • Use minimum roller or presser foot pressure.

9. Twisted Legs :

Description : is where the sideseam twists around to the front   of the pant and distorts the appearance of the jeans .

twisted legs jeans

Recommended Solution :

  • Instruct the sewing operator to
    match the front and back properly so they come out the
    same length. Sometimes notches are used to insure proper
    alignment. They should NOT trim off the front or back with
    scissors to make them come out the same length.
  • Make sure the cut parts are of equal length coming to the
    assembly operation.
  • Check fabric quality and cutting for proper skew.
  • Make sure the sewing machine is adjusted
    properly for uniform feeding of the top and bottom plies

8. Disappearing Stitches in Stretch Denim

Description :  is where the  thread looks much smaller on seams sewn in the warp direction than in the weft direction of the fabric

jeans stitching

denim jeans stitching

Recommended Solution :

  • Use a heavier thread size (T-120,  ON STRETCH DENIM
    T-135, T-150) on topstitching.
  • Go to a longer stitch length  (from 8 to 6 spi). 3) Make sure the thread tensions are as loose as possible so the thread sits on top of the
    fabric rather than burying in the fabric on seams sewn in
    the warp.

10. Thread Discoloration after Laundry

Description : is where the thread  pics up the indigo dyes from the fabric giving the thread a ‘dirty’ appearance. A common discoloration would be the pick-up of a greenish or turquoise tint.

denim stitching

Recommended Solution :

  • Use thread  with proper color fastness characteristics.
  • Correct PH level (too low) and Water Temperature (too low) during
    laundry.
  • Use the proper chemicals & laundry cycles.
  • Use Denimcol PCC in wash or similar additive.
  • Do Not overload washers with too many garments at one time

Need further  info on denim stitching , visit A&E website or contact them.

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