USES OF CAM IN SEWING MACHINE

CAMSA rotating part designed to impart reciprocating or oscillatory motion to follower.

On basis of physical shape:-

Radial cam-follower moves perpendicular to the axis of cam.

Cylindrical cam-follower moves parallel to the axis of cam. Types of cams

On basis of surface in contact:-

Knife edge follower-

Roller follower-Follower classification

Flat faced follower-

Spherical follower

Based on motion

Oscillatory-to and fro

Reciprocatory- up and down or back and forth

Based on line of action

Radial-line coincides with axis of cam

Offset-line do not coincide with the axis of cam

A sewing machine is a textile machine used to stitch fabric or other material together with thread.

LOCK STITCH

The upper thread runs from a spool kept on a spindle on top of or next to the machine, through a tension mechanism, a take-up arm, and finally through the hole in the needle. The lower thread is wound onto a bobbin, which is inserted into a case in the lower section of the machine. To make one stitch, the machine lowers the threaded needle through the cloth into the bobbin area, where a hook catches the upper thread at the point just after it goes through the needle. The hook mechanism carries the upper thread entirely around the bobbin case, so that it has made one wrap of the bobbin thread.

Then the take-up arm pulls the excess upper thread ( from the bobbin area ) back to the top forming the lockstitch ideally in the center of the thickness of the material, the tension mechanism prevents the thread from being pulled from the spool side, the needle is pulled out of the cloth, and the feed dogs pull the cloth back one stitch length, the cycle is repeated as the machine turns mechanically .

CHAIN STITCHTo sew a chain stitch, the sewing machine loops a single length of thread back on itself. The fabric, sitting on a metal plate underneath the needle, is held down by a presser foot. At the beginning of each stitch, the needle pulls a loop of thread through the fabric. A looper mechanism, which moves in synch with the needle, grabs the loop of thread before the needle pulls up. Once the needle has pulled out of the fabric, the feed dog mechanism (which we'll examine later) pulls the fabric forward.

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