Technical problems and solutions involved in garments Manufacturing

Garments Sewing Technical Problems & Solutions

Maruf Mahfuz

Cell no: 01738676060
Email: maruf.txt@gmail.com

Department of textile Engineering

World university of Bangladesh

Types of seam:

There may be hundreds of types of seams. but mainly 8 types of seams are used in garments making which are as follows:

1) Class-1: super imposed seam

2) Class-2: lapped seam

3) Class-3: bound seam

4) Class-4: flat seam

5) Class-5: decorative seam

6) Class-6: edge neating

7) Class-7: no descriptive name

8) Class-8: no descriptive name

1) Class-1(super imposed seam):

This is the most common garments. The simplest seam type within this class is formed by superimposing the edge of one piece of material on another. A Varity of stitch types can be used on this type of seam both for joining the fabric and for neating the edge or for achieving both simultaneously. Especially it is used in seam of shirt & trousers.

2) Class-2: (lapped seam):

This simplest type of seam of this class is formed by lapping two pieces of fabrics. The advantages & disadvantages of this type of seam are as follows

• Advantages:

1. As the selvedge of fabrics are best inward. The possibility of withdrawal of thread from the selvedge is low. Hence the strength and durability of seam is increased.
2. The possibility of seam slippage is very less

• Disadvantages:

1. Seam thickness is increased.
Use: For decorative effect on jacket and also used in jeans

3) Class-3(bound seam):

In this class, the seam consists of an edge of material which is bound by other. into the binding, the other material may be inserted for achieving an effect of design. Generally a contrasting colored fabric is used for edge binding. In figure (a) the simplest bound seam is shown which is not used in garments manufacturing. Because here fraying occurs in the fabric. The seam is shown in figure (b) is extensively used in garment in both functional and decorative purposes. For producing bound seam folding device is used in sewing machine. Bound seam is generally used in t-shirts, underwear, pants, sleeping suits etc.

4) Class-4 (flat seam):

This class of seam is called flat seam because the two fabric edges do not overlap. Sometimes, for decorative purpose a gap is kept between two edges and then seam is formed. Generally twin needle sewing machines are used for sewing flat seam. This class of seam is used in knitted garments and underwear as their thickness is less.

5) Class-5 (decorative seam):

Previously this class of seam was not regarded as seam and was given the name “stitching”. The main use of this seam is for decorative sewing on garments where one or more rows of stitches are sewn.

6) Class-6(Edge neating):

Seam types in this class include those where fabric edge are knitted by means of stitches. This is done for preventing fraying of threads of fabric from edges.the simplest type of edge neating is done by over lock machine. The using of folder may make the sewing easy. Various types of stitches can be for producing this class of seam.

7) Class-7:

Seams of these classes add separate items to the edge of a garment part. They are similar to the lapped seam except that the added component has a definite edge on both sides. This type of seam may be used to attach lace or elastic on the edge of fabric. Here a twin needle sewing machine with a folder is used

8) Class-8:

In this seam class only one piece of material is used to construct the seam. The most common seam type in this class is the belt loop as used in jeans, raincoats etc.

Stitch

• Every unit of a seam line formed by interloping, intralooping or interlacing of one or more threads is called stitch. 
• When one loop of a thread is passed through another loop of seam thread, it is called intralooping. 
• When one loop of a thread is passed through another loop of another thread, it is called interloping. 
• When one loop of a thread is passed over another loop of another thread, it is called interlacing.

Stitch Classes: 

About 70 classes of stitch are found to be used. Among them only 18-20 types of stitches are extensively used in garments industry. All these types stitch are grouped in following 6 classes.

1. Stitch Class- 100(Chain Stitch) 
2. Stitch Class-200 (Hand Stitch) 
3. Stitch Class-300(Lock Stitch) 
4. Stitch Class-400(Multi threaded chain stitch) 
5. Stitch Class-500(Over edge stitch) 
6. Stitch Class-600( Covering chain stitch)

(1) Stitch class-100(chain stitch):

Chain stitches are produced by one or more needle threads and are characterized by intralopping. One needle thread is passed through the fabric, from needle loop and secured by next loop formed by the same thread. Thus stitches are produced. This type of stitches i.e. chain stitch is very insecure. In case of breakage any stitch, it unravels very easily. The most common type of stitch of this stitch class-100 is type-101.as it is very insecure, it is generally used for temporary joining, positioning, button holing & button attaching.

(2) Stitch class-200(hand stitch):

The stitches of this class are originated as hand stitches. It produced from a single thread. This thread is passed through the fabric from one side to another and the stitch is secured by the single line of thread passing in and out of the material. Hand stitch is time consuming and costly operation which needs high skill for good appearance. Stitch type-209 is used at the edge of jackets. For producing this stitch special type of needle having eye at the middle and sewing machine is used. The hand stitch machine is hot so fast.

(3) Stitch class-300(lock stitch):

These types of stitches are produced with two or more groups of threads. Here the two threads are joined by interlacing. Loops of one groups are passed. Through the material and are by the thread of second group. One group is normally referred to as the needle thread and the other as bobbin thread. This stitch has enough strength and can be stretched up to 30%. It has the same appearance on both sides of the fabric which is not available in other stitches. Lock stitch are also much secured. They do not unravel in case of yarn breakage. The thread in a lock stitch generally beds well into the fabric which improves its abrasion resistance. The disadvantages of this class of stitch is, here the bobbin contains less amount of yarn than needle thread package. So the bobbin runs out during sewing. So the threading of bobbin is time consuming

(4) Stitch class-400 (multithread chain stitch):

This class of stitch is formed with two or more groups of thread. Loops of one group of thread are passed through the material and are secured by interlacing and interloping with loops of other groups. Here one group of thread is called needle thread and the other is called looper thread.

The most common and mostly used type of stitch of this class is stitch type – 401 which is produced by one needle thread and one looper thread.

(5) Stitch class-500(over lock stitch):

The stitch types in this class are formed with one or more groups of threads. Here at least one group of thread passes around the edge of material. So no thread from the fabric edge can come out. The most frequently used stitch of this type have one or two needle threads and one or two looper threads and thus forms a narrow band of stitching along the edge of the fabric. A trimming knife of the machine ensures a head prior to sewing.

(6) Stitch class-600(covering chain stitch):

These types of stitches are generally produced with 3 groups of threads. Threads of two groups can be seen from either side. The first group of thread is called needle thread, second group of thread is called top cover thread and the third group of thread is called bottom cover thread. The stitch of this class is very complex and up to 9 threads can be used.

This type of stitches is used in knitted garments, attaching laces, braids and elastic in garments.

Sewing problem:

Stitch, seam feed system; needle and thread together determines the seam appearance & performance. The problems which arise when material are sewn vary in their seriousness. Some are major problems which cannot be over locked and for these garments will be rejected by the inspector, where as someone minor problem which are negligible in low quality garments.

The sewing problems are as follows:

1. Problems of stitch formation.

(a) Slipped / skipped stitch

(b) Staggered stitch

(c) Unbalanced stitch

(d) Variable stitch density.

(e) Needles thread breakage.

(f) Frequent bobbin thread breakage

2. Problems of fabric distortion known as pucker or pucker problem.

(a) Seam pucker due to differential fabric stretch

(b) Dimensional instability of fabric

(c) Shrinkage of sewing thread

(d) Seam pucker due to fabric construction

(e) Seam pucker due to miss- matched patter

3. Problems of damage of fabric along the stitch line / fabric damage problem

(a) Mechanical damage

(b) Needle heating damage

1) Problems of stitch formation:

a) Slipped stitch:

If the continuation of stitches in a seam line is hampered by slipping some stitches it is called slipped or skipped stitch

Causes	Remedies
Hook or looper is not able to hold the needle loop.	Þ    Timing of hook or looper with needle should be appropriate. Þ    Replace the needle position correctly.
Loop size of needle thread is small.	Adjust needle & thread size.
Tension variation in looper & needle thread.	Adjust tension.

b) Staggered stitch

If the stitches produced by needle are not Parallel with the seam line they are called staggered stitch

Causes	Remedies
Needle deflection / vibration.	Þ    Needle size should be increased. Þ    Used tapper needle.
Faulty movement of feed dog.	Þ    Correct the feed dog motion.
Incorrect controlling of fabric into the feed mechanism.	Þ    Adjust the pressure of pressure foot. Þ    Change feed mechanism.
Due to lose fitting of needle butt inside the needle bar.	Þ    Assuring tight fitting of needle inside the needle bar

c) Unbalanced stitch:

Generally found in lock stitch. If the interlacement of the needle thread and bobbin thread does not take place at the middle of two layers of fabric unbalanced stitch is produced.

Causes	Remedies
Incorrect tension of sewing thread	Adjust thread tension
Incorrect passage of thread through the guide	Correct the passage of thread.

d) Variable stitch density: 

It is the variation of number of stitches per unit length of seam. The causes of variable stitch density and their remedies are mentioned below

Causes	Remedies
Insufficient pressure of pressure foot, causing uneven feeding of the fabric through the machine	Correct pressure
Materials of sticky or slippery surface	Increase pressure

e) Needle thread breakage:

Causes	Remedies
Improper unwinding of thread from package.	Place the package correctly so that unwinding can be performed easily.
Thread twisted in the guide.	Guide the thread correctly through the guide.
higher thread tension	Reduce tension in tension disc
Sharp edges of hook point, needle eye, bobbin case etc	Polish the sharp edges
Excess needle heating	Use higher quality needle / use lubricant
Lower quality of thread	Change thread

f) Frequent bobbin thread breakage:

Causes	Remedies
Faulty winding of thread in bobbin	Adjust bobbin winder correctly
Higher tension of bobbin thread	Reduce tension
Sharp edge of bobbin case	Polish the sharp edge
Improper fitting of bobbin case	Bobbin dimension should be checked
Bobbin or bobbin case may worn out	Change or repair bobbin

2) Problems of fabric distortion known as pucker or pucker problem:

Seam pucker is a major problem. Pucker is a wrinkled appearance along a seam when compared to a smooth fabric. 

Causes of seam pucker discussed below:

a) Seam pucker due to differential fabric stretch:

The prime requirement of feeding system is that it should move the plies of fabric past the needle and that all the plies should move together. But because of some reason if there is unequal stretch between the layers of fabric, then feeding of one layer becomes more than the other layer giving a rise to seam pucker.To remove feeding pucker the feed mechanism of the machine should be changed.

b) Dimensional instability of fabric:

When two or more than two layers of fabric are sewn and if one layer shrinks more than other after washing, seam pucker is seen. Hence before sewing two or more layers of fabrics, the potential shrinkage property should be considered.

c) Shrinkage of sewing thread:

If the sewing thread shrinkage, then seam pucker is occurred. This type of seam pucker is seen after washing on ironing. Before sewing the shrinkage potential of both the thread and fabric should be known. Synthetic threads have negligible wet shrinkage and should be used to remove the problem.

d) Seam pucker due to fabric construction:

In a compact fabric having high EPI & PPI, there is very little space left between the warp and weft yarns. While sewing such fabrics the threads are displaced around the needle and because of lack of space, pucker may be seen along the holes created by the needle. Such type of seam pucker is very difficult to remove but following steps may be taken:

• By using fine needle and fine thread.
• Reduction of stitch density.
• By changing the fabric it is possible.

e) Seam pucker due to miss-matched pattern:

If two pattern pieces of unequal length are joined, then one is joined with another by creating construction. This causes seam pucker. Mainly this type of problem is occurred due to designer fault.

3) Problems of damage of fabric along the stitch line / fabric damage problem:

The problem of fabric damage along the stitch line is mainly because of the use of unsuitable needle, sewing unsuitable fabrics or combination of both, there are two types of fabric damage because of needle

a) Mechanical damage.

b) Needle heating damage.

a) Mechanical damage:

Any damage of fiber on yarn of fabric by needle. 

To minimize the possibility precautions are:

• Needle size and point should be properly selected and needle should be free from damage or bending.
• Machine speed should be reduced.
• Application of lubricant which are spacing along the stitch line before sewing.
• Fabric sew ability test for specific or sensitive fabric should be done before sewing.

b) Needle heating damage:

Needle heating occurs as a result of friction between the needle & thread and between needle & fabric during sewing. The temperature may be 300°c to 350°c. At that temperature needle or fabric or both may be changed. In case of thread and fabric containing natural fiber has less possibility of damage. But synthetic fibers will melt at such high temperature. The damages are prevented by doing following apparatus:

• Speed: Slowing down the sewing speed to decrease the heat generation at the needle.
• Needle size and shape: By using finer needle, the temperature can be reduced.
• Cool air: By the flow of cool air through the needle, the temperature can be reduced to 70°c
• Lubrication: If lubrication is done along the seam line on thread and on needle the heat generation due to friction is reduced considerably.
• Sewing length: For long length sewing machine speed is required to drop & vice-versa.