What are words the elements to measure stitch quality

Principle of Lock Stitch Formation • Stitch class-300 is called lock stitch.. • One group of thread is passed through the fabric and interlaced with the another group of thread and for

What are the elements to measure stitch

quality?

Stitch quality is measured with :

• Stitch size.

• Stitch tension.

• Stitch sequence.

• Elasticity.

• Resilience.

• Elongation.

• Fabric distortion.

• Yarn severance.

• Abrasive strength.

Principle of Lock Stitch

Formation

• Stitch class-300 is called lock stitch It can be

formed by the interlacing of two or more

threads.

• One group of thread is passed through the

fabric and interlaced with the another group of thread and formed lock stitch.

• One set of thread is called is needle thread and

another set of thread is called bobbin thread.

Lockstitch utilizing a rotating hook invented by Allen B Wilson This is employed on many modern machines

The following are the steps referred as the principle of stitch

class-301 formation :

Step-1

• After finishing 2nd stitch the needle and the sewing

thread are in the top position, preparing for next stitch.

• In this situation thread take up lever goes to its

maximum position and fabric has advanced one stitch.

• Needle is entered with threads through the fabric and

reached to its lowest position.

• Again needle moves up a bit and stops for a while At that

time thread take up lever also moves downwards and a loop

is formed due to the upward moving of needle The formed loop is called needle loop.

Fig : Step-1

• It is informed that, the hook of bobbin holder

always rotates at half circle.

• Due to rotation of the half circle bobbin holder

hook catches the needle loop and moves the needle loop over the bobbin case.

• Interlacement takes place between the loop of

bobbin thread and needle thread.

Principle of Lock Stitch

Formation

Fig : Step-2

• Needle start to move up wards with needle

thread and take up lever also starts to

move upward As a result, needle loop pulls the bobbin thread upward.

• In the mean time fabric is also moves one

stitch forward due to feed dog mechanism

Principle of Lock Stitch

Formation

Fig : Step-3

• Loop clears bobbin and take-up draws to loop closed.

• It should be remembered that tension of bobbin thread

and needle thread should be proper for correct

appearance of stitch formation So that it must be

adjusted before sewing start.

• Needle thread tension can be adjusted by tensioning

disc and thread guide path changing.

• Bobbin thread tension can be adjusted by small screw

which is attached on the case through tightening and loosening.

Principle of Lock Stitch

Formation

Fig : Step-4

• In this stage, needle descends to lowest

point to stroke.

• New loop has been formed and is

passing around bobbin.

• Loop is pulled up to complete the stitch.

Principle of Lock Stitch

Formation

Fig : Step-5

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