Principles of Lock and Chain Stitch Formation and Its Differences

Here in this article, you will learn Principles of Lock and Chain Stitch Formation and Its Differences with phase wise details.

The Principles of Lock Stitch Formation

• Lock stitch m/c requires two groups of threads to form a stitch.
• A needle thread that feeds from the top & a lower thread from a bobbin.
• A rotary hook catches the needle thread loop as it passes around the bobbin &
  interlocks the two threads.
• The lock stitch m/c can be distinguished by the winding device provided for the bottom
  thread.

Phases of Lock Stitch Formation

Phase-1: The needle is inserted into the material

Phase-2: As the needle moves up-wards from its lowest position the needle thread forms a loop which is caught by the point of the hook.

Phase-3: The hook enlarges the needle thread loop.

Phase-4:  In this phase, the thread loop is guided around the bottom thread of the spool.

Phase-5: The beginnings of interlacing will be done in this phase.

Principles of Chain Stitch Formation

Phase-1:

• The needle is entered through the fabric with the thread & reaches to its lowest position.
• Needle contain old loop around its blade
• When needle moves on upward there will be the formation of a new loop.

Phase-2:

• The new loop is caught by the looper (above the needle eye below the old loop)
• The needle moves upward
• The old loop is cast off from the needle blade and slides on the base of the new loop, which is still held by the looper.
• Between the new and old loop, an interlacement is to be formed under the fabric
• In that time fabric is also moved one stitch forward due to the feed dog mechanism.

Phase-3:

• The looper enlarges the new loop so that when needle again entered through the fabric it passes through the loop.
• Then the looper leaves the loop, which held on the needle blade.
• This loop now becomes the old loop.

Difference Between Chain Stitch and Lock Stitch

Chain Stitch	Lock Stitch
Stitches are formed by two or m regroups of threads, needle thread & looper thread.	There will be at least two types of threads, one is needle thread and other is bobbin thread.
The Threads are bound together by interlacing and interloping.	The Threads are only bound by interlacing.
Looks like lock stitch at the top side and double chain at under.	The visibility look of a lock stitch is the same on both sides of the fabric.
Strength is higher than look stitch.	Lower strength than chain stitch.
Possibilities of seam pucker formation are less compare to lock stitch.	Possibilities of seam pucker are more than chain stitch.
Extensibilities is 30%	Same, sometimes less than chain stitch.
No need of back tacking at finishing end, but secured by one (cm) thread at finishing the end.	Stitches are secured by back tacking at the starting and finishing the end.
m/c speed 8000 spm (stitch per min)	m/c speed 6000 spm.
Thread consumption is high.	Thread consumption is less.

Amarta Sarkar
B.Sc. in Textile Engineering (Major in Apparel Manufacturing Technology) (BUBT)
EMBA (Studying) (JnU)
Email: [email protected]