Stitches

Stitches

Properties of stitches:

Properties of stitches are 1.size 2.tension 3.consistency.

1. Stitch size:

Stitch size has three dimensions

a. length b. width c. depth.

a. Stitch length:

It is defined as the number of stitches per inch (SPI) and is an indicator of quality. It is determined by the amount of fabric that is advanced under the needle between penetrations.

High SPI means short stitches and low SPI means long stitches.

•Long stitches are less durable and are considered low quality.

•A shirt with 22 SPI are considered high quality than similar shirt made with 8 SPI.

•A seam sewn with 8 SPI could be sewn nearly three times faster as requiring 22 SPI if maximum speed was maintained.

b. Stitch Width:

•Refers to horizontal span covered in the formation of one stitch.

•Stitch width is referred to as gauge.

c. Stitch depth:

•Distance between upper and lower surface of stitch determines the stitch depth.

•Stitch depth should be sufficient to catch all fabric plies.

Stitch Classes:

Stitch classes are defined in ASTM D 6193 are based on thread formation created by a sewing machine.

These are

·         Class 300 -Lock stitch

·         Class 100 -Chain stitch

·         Class 400 –Multithread Chain Stitch

·         Class 200 -Hand Stitch

·         Class 500 -Overedge Stitch

·         Class 600 -Cover Stitch

Class 100-Chain Stitch:

The chain stitch class is formed with needle threads that form a loop on the underside of the fabric with the help of looper. There is no lower thread .type101, 102, 103, 104 are used mainly in this class.

Class 200 -Hand Stitch

It consists of stitch formation done by hand with the single strand of thread. Hand stitches are characterized by single line of thread passing in and out of the fabric. It includes stitch types 201, 202, 203, 204 and 205.

Class 300 lock stitch:

•It is most frequently used and easiest to understand.

•301 lock stitches sometimes referred as plain stitch or straight stitch. It is most familiar and used in industry.

•304 stitch is zigzag stitch.

•Other types are 306, 313, and 314.

Lockstitch machines are slower than other classes of industrial machines.

•Operating speed ranges from 3000 to 5000 rpm while other classes of machine operate at 9000 rpm or more.

•Lock stitch machines have more downtime because they operate with limited supply from bobbins that have to be replaced as they run out.

Class 400 multithread chain stitch:

In multithread chain stitch we use one or more needles and a looper.

Class 500 Overedge stitches:

In class 500 we use multiple needles and a looper.501, 502,503, 504, 505, 514,515, 516, 512, 521 are main types of this class

Class 600 cover stitch:

They are also called flat lock or flat seam stitches.

601,602, 603, 604, 605, 606 and 607 are the types of this class.

Seam:

A seam is a line where two or more fabrics are joined.

Dimensions of seam:

1. Seam length

2. Seam width

3. Seam depth

Seam Length:

Total distance covered by continuous series of stitches such as side seam or shoulder seam.

Seam allowance:

It is measured form the cut edge of the fabric

to the main line of stitches.

Seam depth:

It is the thickness of a seam. According to ASTM Standard D6193, there are four Seam classes and two stitching classes. These seam classes are

1. Super imposed seam

2. Lapped seam

3. Bound seam

4. Flat seam

The stitching classes are

1. Edge Finishing

2. Ornamental stitching

Superimposed Seam:

This type of seam is formed by joining two or more pieces of fabric with one piece superimposed over the second piece.

This class consists of 57 different seam types

Lapped seam:

Seams in which two or more plies of fabric are in opposite direction. This is the largest seam class with 101 different types

Bound Seam:

These are the seams in which one piece of the fabric is sewn over the edge of one or more pieces of fabric. It has 18 types.

Flat seams:

This class of seam is formed by sewing two parallel pieces of the fabric together.

This class has 6 different types.

Stitching classes:

Edge finishing In this class edge of the stitch is finished with stitching. This is also called hemming and it is used in sleeve hemming and bottom hemming.

Ornamental stitching:

It may be used on single ply of fabric for decorative purposes.