Seam Quality Defects

8/10/2019 Seam Quality Defects

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American & Efird, Inc. Technical Bulletin

10/10/02 Page 1

Common Seam Quality Defects

Restitched Seams / Broken Stitches

Excessive RestitchedSeams

DESCRIPTION: Where a "splice" occurs on thestitch line. If this occurs on Topstitching, then theseam does not appear to be 1st quality

merchandise. Caused by 1) thread breaks orthread run-out during sewing; or 2) cut or brokenstitches during a subsequent treatment of thefinished product (i.e., stone washing).

MINIMIZING THREAD BREAKAGE: 1) Use abetter quality sewing thread. This may includegoing to a higher performance thread designed to

minimize sewing interruptions. (See the ThreadSelection Guide and/or Minimizing ThreadBreakage & Skipped Stitches); 2) Insure propermachine maintenance and sewing machineadjustments; 3) Make sure sewing machines areproperly maintained and adjusted for the fabric andsewing operation. (See Machine MaintenanceChecklist .); 4) Observe sewing operators forcorrect material handling techniques.

Skipped Stitches

401 Chainstitch 503 Overedge 301 Lockstitch - Skipped

Stitches

401 Skipped Stitch

DESCRIPTION: Where the stitch length isinconsistent, possibly appearing as double thenormal stitch length; or where you can see that thethreads in the stitch are not properly connectedtogether. Caused by the stitch forming device in thesewing machine missing the thread loop duringstitch formation causing a defective stitch. Onlooper type stitches, this will allow the stitch tounravel causing seam failure.

MINIMIZING SKIPPED STITCHES: 1) Use a betterquality sewing thread. This may include going to ahigher performance thread designed to minimizesewing interruptions. (See the Thread SelectionGuide and/or Minimizing Thread Breakage &Skipped Stitches); 2) Insure proper machinemaintenance and sewing machine adjustments; 3)Make sure sewing machines are properlymaintained and adjusted for the fabric and sewingoperation. (See Machine Maintenance Checklist );4) Observe sewing operators for correct materialhandling techniques.






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Seam Failure - Seam Slippage

Seam Slippage on Rayon Fabric

DESCRIPTION: Where the yarns in the fabric pullout of the seam from the edge. This often occurson fabrics constructed of continuous filament yarnsthat are very smooth and have a slick surface. Alsocaused by loosely constructed fabrics.

MINIMIZING SEAM FAILURES - SEAMSLIPPAGE: 1) Consider changing the seamconstruction to a French seam construction; 2)Increase the seam width or width of bite; 3)Optimize the stitches per inch; 4) Contact yourfabric supplier.

Needle Cutting on Knits

DESCRIPTION: Where needle holes appear alongthe stitchline that will eventually turn into a "run".Generally caused by the needle damaging thefabric as it is penetrating the seam.

MINIMIZING NEEDLE CUTTING ON KNITS: 1)Make sure the proper thread size and needle typeand size are being used for the fabric (SeeReducing Needle Cutting ); 2) Make sure thefabric has been properly stored to prevent dryingout and has been finished properly; 3) Check withyour fabric manufacturer.




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Excessive Seam Puckering - Wovens

DESCRIPTION: Where the seam does not lay flatand smooth along the stitchline. Caused by one ofthe following: 1) Feed Puckering - where the pliesof fabric in the seam are not being aligned properlyduring sewing; 2) Tension Puckering - where thethread has been stretched and sewn into the seam.The thread then causes the seam to draw back andpucker; 3) Yarn Displacement or structural jamming- caused by sewing seams with too large of threadthat causes the yarns in the seam to be displaced,giving a puckered appearance.

MINIMIZING EXCESSIVE SEAM PUCKERING: 1)Use the correct thread type and size for the fabric.In many cases, a smaller, higher tenacity thread isrequired to minimize seam puckering but maintainseam strength (See the Thread Selection Guide or Minimizing Seam Puckering ); 2) Sew withminimum sewing tension to get a balanced stitch;3) Make sure machines are set up properly for thefabric being sewn; 4) Check for proper operatorhandling techniques.

Puckered Seams - Knits & Stretch Wovens

Stretch Denim - Wavy Seams

DESCRIPTION: Where the seam does not lay flat

after stitching.

SOLUTIONS: 1) If sewing machines are equipped

with differential feed, set them properly for thefabric; 2) Use minimum presser foot pressureduring sewing; and 3) Observe operator for correcthandling techniques. Too much stretching of thefabric by the sewing operator will cause thisproblem. (See Sewing Stretch Knits.)




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Excessive Seam Grin

DESCRIPTION: Where the stitch balance is notproperly adjusted (stitch too loose) and you cansee the seam opening up. To check for Seam Grin,apply normal seam stress across the seam andthen remove the stress. If the seam remainsopened, then the seam has too much "grin

through".

SOLUTIONS: To correct, readjust the sewingmachine thread tensions so that the proper stitchbalance is achieved. Too much tension will causeother problems including seam failures ("StitchCracking"), excessive thread breakage, andskipped stitches.

Improper Stitch Balance - 301 Lockstitch

Poor Stitch Balance –

Too Loose

Proper Stitch Balance

DESCRIPTION: Where loops are seen either onthe bottomside or topside of the seam. This isparticularly evident with different colored needleand bobbin threads. Also, where the stitch is tooloose.

SOLUTIONS: 1) Use a quality thread withconsistent frictional characteristics; 2) Properlybalance the stitch so that the needle and bobbinthreads meet in the middle of the seam. Alwaysstart by checking the bobbin thread tension tomake sure it is set correctly, so that the minimumthread tension is required to get a balanced stitch.




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Improper Stitch Balance - 401 Chainstitch

Stitch Too Loose Proper Stitch Balance Proper Stitch Balance

DESCRIPTION: Where the loops on thebottomside of the seam are inconsistent and do notappear uniform.

SOLUTIONS: 1) Use a quality thread withconsistent frictional characteristics; 2) Properlybalance the stitch so that when the looper thread isunraveled, the needle loop lays over half way to thenext needle loop on the underside of the seam.

Improper Stitch Balance - 504 Overedge Stitch

Improper Stitch Balance Purl Not on Edge Proper Stitch Balance

DESCRIPTION: Where the needle loop is not

pulled up to the underside of the seam and the"purl" is not on the edge of the seam.

SOLUTIONS: 1) Use a quality thread with

consistent frictional characteristics; 2) Properlybalance the stitch so that when the looper thread isunraveled, the needle loop lays over half way to thenext needle loop on the underside of the seam.




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Ragged/Inconsistent Edge - Overedge Or Safetystitch Seams

DESCRIPTION: Where the edge of the seam iseither extremely "ragged" or "rolls" inside the stitch.

SOLUTIONS: 1) Make sure the sewing machineknives are sharpened and changed often; 2) Theknives should be adjusted properly in relationshipto the "stitch tongue" on the needle plate to obtainthe proper seam width or width bite. In the photo,the trimming knives have been set wider than the"stitch tongue" on the needle plate causing the"ropy" appearance.

Unraveling Buttons

DESCRIPTION: Where a tail of thread is visible onthe topside of the button and when pulled, thebutton falls off.

SOLUTIONS: 1) Use a quality sewing thread tominimize skipped stitches; 2) Specify attaching thebuttons with a Lockstitch instead of a single threadChainstitch Buttonsewing machine.

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Seam Quality Defects