Page 171 - CTS - Sewing Technology - TP - Volume - 2-0

SEWING TECHNOLOGY - CITS

Module 6: Special Sewing Machine and their
Working Principle

EXERCISE 34 : Stitches

Objectives

At the end of this exercise you shall be able to
• classify the stitch types
• learn the stitch formation
• learn about different machines for different stitch types
• practice stitch types on different sewing machines.
Procedure

Stitch Forming Devices
The basic principle of all machine sewing depends on consistent loop formation. During sewing the needle
descends through the fabric to the bottom of its stroke and as the needle rises a loop of sewing thread is formed
in the scarf of the needle. This loop of sewing thread is picked up by one of two stitch forming devices namely
the hook or the looper. A third stitch forming device known as a spreader is used in some stitch types to carry the
sewing thread from one stitch forming device to another.
The sewing machine hook be it rotary or oscillating shuttle interlocks the needle thread with the bobbin thread. A
looper, used in chain stitch formations, interloops the thread that it carries with another thread.
Steps of Stitch Formation
There are five basic steps to the formation of all stitch types. They are:
1 Penetration – the needle penetrates the fabric carrying the needle thread
2 Loop formation – a loop of sewing thread is formed in the scarf of the needle as the needle begins to rise
from the bottom of its stroke
3 Conformation – this is where the threads are arranged above, below or around the material being sewn
4 Cast off – is where the needle thread loop is freed from the lower stitch forming device
5 Stitch setting – when the thread is drawn onto or into the material
Stitch Types Fig 1
101 – Single Thread Chainstitch
The 101 Single thread chainstitch is formed using just one
sewing thread introduced by the sewing needle. Stitch Type
101 is most often used for temporary stitching [or basting]. Its
main disadvantage is its tendency to run back from the finishing
end of the seam. (Fig 1)

103 – Single Thread Blind hemming
The stitch type 103 known as single thread Blindstitch or Blind Fig 2
Hemming. Again its main disadvantage is seam runback. This
stitch is formed by using a curved needle which enters and
exits the fabric from the same side carrying a needle thread.
The needle thread interloops with a blind looper on the surface
of the material.Typical applications are hemming and lapel
padding operations. (Fig 2)

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