Sewing Problem

Sewing problems consist of-

1. Problems of stitch formation.
2. Problems of seam pucker.
3. Fabric damage at the seam line.

1. Problems of stitch formation 

a) Slipped stitch:

If the upper thread in continuous stitches can not pick the lower thread i.e. binding miss during stitch formation is called slipped stitch.

Causes:

• Loop size or needle is small.
• Needle deflection or bending.
• Tension variation in lopper and needle thread.
• Hook or lopper or needle is not able to hold the thread loop in proper time.

Remedies:

• Timing of (hook or lopper) with needle should be adjusted properly.
• Adjust needle and thread size.
• Adjust tension property.
• Change of thread.

b) Staggered stitch:

If the stitches produced by needle are not parallel with the seam line, staggered stitches formed.

Causes:

• Needle vibration or deflection.
• Wrong needle point.
• Not proper adjust of needle size and thread size.
• Faulty movement controlling of fabric into the feed mechanism.

Remedies:

• Needle size should be increased.
• Change of needle or thread size.
• Change of feed mechanism.

 

c) Un balanced Stitch: 

If the interlacement of the needle thread and bobbin thread does not takes place at the middle of two layers of the fabric then unbalanced stitch is produced.

Causes:

• Incorrect tension of sewing thread.
• Incorrect passage of thread through the guide.
• Due to insufficient lubrication, (uneven) tension variation increased.

Remedies:

• Adjust thread tension.
• Correct the passage of thread.
• Use good quality of thread.

d) Variable stitch density:

If the no. of stitch varied in the seam line per unit length, then variable stitch density occurred.

Causes:

• Insufficient pressure of presser foot, causing uneven feeding.
• Feed mechanism is not working properly.
• Improper unwinding of thread.
• Twisting of needle in the bottom of thread package.
• Fraying of thread in the needle.
• More tension in the thread.
• Becoming of more heating of thread and hook.
• Use of low quality of thread.

Remedies:

• Uses of improved feed mechanism.
• Increase of pressure of presser foot.
• Proper threading of sewing thread.
• Thread can be changed.
• Proper use of lubricant.
• Use of good needle.
• Finer thread can be used.
• Tension in thread must be adjusted.

e) Frequent thread breakage:

Causes:

• Improper unwinding of thread from package.
• Higher thread tension.
• Excess needle heating.
• Lower quality of thread.

Remedies:

• Reduce tension in tension disc.
• Reduce thread tension.
• Use of strong yarn.
• Change the needle if required.
• Use coarser (মোটা)needle.
• Use of high quality needle.
• Use lubricant.
• Use needle cooler.
• Confirm oil supply.
• Change of thread.

2. Problems of seam pucker

Pucker is a wrinkled appearance along with sewing line.

a) Unequal stretch on fabric:

Causes :

• If two or more plies fabrics are sewn together, one ply will be feed more than other and seam pucker create due to uneven stretch.

Remedies:

• Improved feed mechanism of sewing m/c.
• Skilled operator and fabric handling would be special process.

b) Fabric dimension instability:

Causes:

•When two or more layers of fabric are sewn together and one layer shrinks more than after washing differential seam pucker is formed.
Remedies::
•Shrinkage difference must be less than 2 %.
•We should test shrinkage of two types of fabric before sewing. 

c) Extension in sewing thread:

Causes:

• While sewing threads are subjected to tension(টেনশনের শিকার) and for tension thread will be extended and after sewing when thread get chance of relaxation then seam pucker formed.

Remedies:

• Tension of the thread should be kept as low as possible.
• By changing the sewing threads.

d) Sewing thread shrinkage:

Causes:

• After sewing, if the sewing threads shrinks due to wash or iron, then seam pucker occurred.

Remedies:

• Shrinkage of sewing thread must be equal to the fabric shrinkage.
• Before sewing, the shrinkage property of both thread and fabric should be known.

e) Fabric construction:

Causes:

• In a compact fabric high EPI and PPI, while sewing of such fabrics, the threads are displaced around the needle because of the lack of space, pucker may be seen along the holes created by the needles.

Remedies:

-Very difficult to overcome this type of problem but to reduce the problems following steps should be taken:

• By using fine / thin needle and fine / thin thread.
• Reduction of stitch density.
• Change the fabric if possible.

3. Fabric damage at the seam line

Causes:

• This type of fault is mainly due to needle specially, bent or damaged needle.
• For this fabric damage, sewing strength becomes low and due to more fabric damage, fabric may be tear off at the sewing line.
• Fabric may be damaged with new and good needle if needle size and needle selection is wrong.
• This fault is visible after washing and wear.

Remedies:

 Two types of fabric damage can be occurred with needle at the seam line: 

• Mechanical damage.
• Needle heating damage.

a) Mechanical damage: 

To minimize the damage, the following steps are taken:

• Needle size and point should be properly selected.
• M/c speed should be reduced.
• Application of lubricant.
• Test the sew ability before sewing of fabric.

b) Needle heating damage:

• The temperature in needle due to friction between needle and fabric is up to 300 –350°C.In this temp, needle or fabric both may be damaged.

We can solve the problem by-

• Less speed of machine
• Proper needle size and shape
• Short length of sewing
• Cool air use
• Lubrication.

What do you mean by Lubrication?

The action of applying a substance such as oil or grease to an engine or component so as to minimize friction and allow smooth movement.(একটি ইঞ্জিন বা উপাদানে তেল বা গ্রীস জাতীয় পদার্থ প্রয়োগ করার ক্রিয়া যাতে ঘর্ষণকে হ্রাস করা যায় এবং মসৃণ চলাচলের অনুমতি দেওয়া যায়।)