Stitching Defects
Sewing defects can be classified into three groups:
- Problems of stitch
- Problem of
- Damage of fabric on the seam
Problems of stitch formation
Slipped stitch
Stitches in the seam line are present in a regular manner. If the interloping or interlacing between the top & bottom thread of the stitch does not take place or is missed is known as slipped stitch or skipped stitch. This is a serious defect in the case of chain stitch than lock stitch. The followings are the causes & remedies of slipped stitch formation.
| Causes | Remedies |
|---|---|
| If hook or looper & needle are not inserted in the loop of thread in time. | Examine the setting & timing between needle & hook or looper. Placing the needle properly. A more secure needle should be used. |
| Irregular thread tension on the upper or lower loop. | The tension of the thread should again be adjusted. |
| Needle deflection. | Needle to be changed. |
| If the needle thread loop size is too small. | Needle size & thread size must be adjusted. |
| Flagging of fabrics during sewing. | The pressure of the pressure foot must be adjusted accurately. The hole of the throat plate & needle size must be adjusted. |
| If the sewing thread is not capable to form a loop. | Thread to be changed |
Staggered stitch
If the stitches produced by the needle are not parallel or become curvy to the sewing line is known as a staggered stitch.
| Causes | Remedies |
|---|---|
| Needle deflection. | Increase the needle size Tapered needles should be used. |
| Due to the wrong blunt needlepoint. | Needle to be changed. |
| Wrong adjustment of needle & thread size. | Needle size & thread size to be changed. |
| The deflected motion of the feed dog. | The motion of the feed dog is to be adjusted. |
| If fabrics are not controlled properly in the feed mechanism. | The pressure of the pressure foot must be adjusted accurately. Feed mechanism to be changed. |
Unbalance stitch
This type of defect is found in the lock stitch machine. If the interlacement of threads does not take place in the middle (i.e. if the interlacement is taken place in the upper or lower position from the middle) of two layers of fabrics then it is known as an unbalanced stitch.
| Causes | Remedies |
|---|---|
| Wrong tension of sewing thread. | The setting of proper tension to the sewing thread. Proper care to the twisting of the thread during sewing. |
| They used the wrong thread path | Use of right thread path. |
| Wrong adjustment of needle thread path. | Use of right thread path. |
| Snagging of the needle with bobbin case & positioning finger. | Bobbin’s case to be smooth. The positioning finger is to be set again. |
| If the thread is not lubricated. | Better qualities of the thread must be used. The thread must be lubricated. |
Variable stitch density
Stitches per unit length should be uniform, If it is not then it is called variable stitch density. The main cause of variable stitch density is an irregular feed of fabric due to insufficient pressure of pressure foot. The following are the cause & remedies of variable stitch density formation
| Causes | Remedies |
|---|---|
| The improper unwinding of thread from the package during sewing. | The position of the thread guide must be 2.5 times higher than the position of the thread package. Also, proper care should be kept to the thread package, not to tiling |
| Twisting of needle thread in the bottom of the thread package. | A foam pad must be used to the bottom of the thread package. |
| Snarling of thread before tension disk. | Winding of more threads in the thread guide & to keep less tension to the tensioning disk. |
| Twisting of thread in the thread guide. | Proper threading of sewing thread during sewing. |
| More tension to the thread. | The tension of the thread should be less or use high-strength threads. |
| Use of broken check spring. | Check spring to be changed. |
| If the edge of the throat plate, hook point, needle guard, bobbin case, needle groove, needle eye & so on are sharpened. | The edges must be smooth & the needle must be changed as needed. |
| Fraying of thread in the needle. | Fine thread must be used or use a heavy needle. |
| Thread gets heated more | A high-quality needle must be used. Needle lubricant must be used. A needle cooler must be used. |
| Hook gets heated more | Lubricant must be available. Examine the distance between the needles & hook. |
| Use of low-quality threads. | Thread to be changed. |
Frequent thread breakage
Frequent breakage of thread especially, when there needs to open out the sewing to solve the problem. The following are the causes & remedies of frequent thread breakage.
| No. | Causes | Remedies |
| 01 | Wrong winding of threads onto the bobbin. | Proper winding of threads onto the bobbin. The pre-wound bobbin may be used. |
| 02 | More tension to the bobbin threads or more rotating of the bobbin. | The tension must be adjusted to the bobbin threads. Use of washer to prevent more rotation of bobbin. |
| 03 | If the edges bobbin case, looper eye & so on are more sharpened. | The edges to be smooth. |
| 04 | Wrong fitting of bobbin case. | Examine the size & type of bobbin. Examine the damaging of bobbin case. |
Broken Stitches
When stitches are broken during sewing is called broken stitch.
Cause
Where the thread is being broken where one seam crosses another seam (ex: bar tacks on top of waistband stitching, seat seam on top of riser seam.)
Remedies
- Where the thread is being cut, use a large diameter thread on operations.
- Make sure the proper stitch balance is being
- Use needles with the appropriate needle
- At regular intervals on operations, change the needles where they occur
Problems of pucker
Puckering is a wrinkle appearance along a seam line in a smooth fabric. It is one of the frequently occurring defects. Puckering shows that as if there is too much fabric & not enough thread in the seam & as if the thread is drawing the seam in.
This is the reason why sewing thread is often blamed for causing puckering though there are other factors as well as for the promotion of puckering. They are given below:
- Fabric structure
- Seam construction
- Needle size
- Material feeding problem
- Wrong thread tension
- Unsuitable thread.
Reasons of Puckering
Fabric dimensional instability. Extension of sewing thread. Sewing threads shrinkage. Structural jamming of fabric. Mismatched patterns.
Variable or uneven stretch on fabric plies
Causes
There is a great possibility of occurring seam pucker in case of more plied of fabrics when sewing together.
Due to variable stitch on fabric plies, they will not feed equally to sewing m/c & create seam pucker.
This type of pucker is seen as a limitation of the feed mechanism.
Remedies
- Taking proper care during
- Using proper feed
Fabric dimensional instability
Causes
If the shrinkage of sewn fabric plies is not the same or equal then Seam pucker will create after washing.
If the shrinkage percentage of the area of two pieces of fabrics is more than 2, then seam pucker will occur after sewing the fabric together.
Remedies
Use suitable feed mechanism, Maintain shrinkage and take extra care during
Extension of sewing thread
Causes
If the tension on the needle thread is higher than the under the thread, then the seam pucker will be produced or relaxed.
Due to tension, the length of the thread is extended slightly. When the fabric is displaced or descends from the machine after sewing, shrinkage of thread & fabric occurs due to their tendency of coming to the original position.
If the shrinkage percentage of thread is higher than the fabric seam pucker happens.
Remedies
- To give sufficient thread
- To maintain
Unraveling Seams
Cause
Generally occurs on 401 chain stitch seams where either the stitch has been broken or a skipped stitch has occurred. Unless the seam is re-stitched, this will cause seam failure.
Remedies
- Ensuring Proper machine maintenance and machine
- Sewing operators to follow correct material handling
Re-stitched Seams
Where there is a “splice” on the stitch line. The seam does not appear to be 1st quality merchandise if this occurs on topstitching.
Causes
Thread breaks or thread run-out during sewing. Cut or broken stitches during a subsequent treatment of the finished product (i.e., stone washing).
Remedies
- Use a better quality sewing thread and minimize sewing interruptions
- Use higher performance thread specifically designed for that
- Ensure sewing machine adjustments and proper machine
- Observe sewing operators for correct material handling
Damage of fabric on the seam line
A garment can be rejected due to damage of fabrics or yarn of fabrics in the seam line. This happens due to wrong needle selection or needle damage. The fabrics are damaged due to defective needles. But it may happen in the case of new or fine needles. There are two types of fabric damaging are available given below:-
Mechanical damage
Damaging of fibers or yarns in the fabrics by the needle is the entire defect of mechanical damage. The followings are the steps to be taken to keep the fabrics free from this type of defect:
- By using the perfect size & shape of the needle & needle point without any defect. By reducing the speed of sewing machines.
- By using lubricant.
- By testing sewability before sewing fabrics.
Needle heating damage
- The damage of fabric is due to friction occurring between the needle & fabrics. The resulting temperature due to friction in the needle is very The fabric can get damaged at that temperature. There is less damage in the case of fabrics made from natural fibers. The following are the steps to be taken to keep the fabrics free from this type of defect:
- By reducing sewing speed, the generation of heat to the needle will be less.
- But it affects production speed and does not suit large production.
- By changing needle Size & shape so that there is less generation of heat to the needle.
- By sewing smaller lengths at higher speeds.
- By blowing cool air on the needle during sewing so that the temperature can be controlled.
- By using lubricant to the needle. By using Teflon coated needle.
- Defects occur due to handling, for instance, spoilage, staining, etc. Defects occur due to oil marks.
- Defects occur due to dirty spots.
Size Measurement Faults
During the manufacturing of garments size of some parts is measured as per requirement. After assembling full garments also dimensions are measured to ensure that the dimension of garments is as per specifications. Faults occurring at this stage is can be reduced very much. During size measurement the parts which are measured are
- Chest
- Waist
- Shoulder
- Sleeve length
- Sleeve opening
- Body length
- Neck width
- Front neck drop
- Back neck drop
- Collar Height
- Arm hole
- Placket length
- Pocket length
- Pocket width
- Bottom part and
- Hem opening etc.,
Garment Twist
A rotation, usually lateral, between different panels of a garment resulting from the release of latent stresses during the laundering of the woven or knitted fabric forming the garment. Torque or spirality may also be used to refer to twist.
Sewing thread shrinkage
Causes
Due to variable shrinkage % of sewing thread & fabric, Seam pucker will create after washing or ironing.
Cotton threads develop puckering when wet or after wash.
Remedies
- To use synthetic
- It is good to know about the shrinkage % of fabric & thread before selection to
Structural jamming of fabric
Causes
When sewing is done by a needle to densely woven fabrics or in which no. of warp & weft yarns are more in one inch, seam pucker happens due to shrinkage of fabric.
Remedies
- By using finer thread &
- By minimizing stitch
- By cutting & sewing on bias angle.
- By using chain stitch instead of the lock
- To change fabric (if necessary).
Mismatched patterns
Causes
Seam pucker will create when two different sizes patterns are sewn together.
The designer is responsible for this. It can also occur due to the wrong selection of patterns.
Remedies
An experienced pattern designer is needed. Change or rectify the pattern.
Hi Komal, your article is very informative. We are selling small sewing machine with brand name akiara. I want some of your suggestion, can you contact me on agrawal _ amit _ s at hot mail dot com
You have said it all what I marveled about is the blind hem stitchine industrial machine in the Collage I went Vogue Style as twenty ten graduate
school of fashion and designing by Joyce Aba Bio was thought by hand Heming and Blind stitches was one mean the hand stitching thanks a lot guys.