Description of the machines and processes
Name- Yeshanthi weeratunga
Part I : Primary and secondary motions of weaving
1)Explain briefly the function and importance of primary & secondary motions of weaving
The weaving process consists of two basic motions
Primary motions - shedding, picking beating-up
Secondary motions- left off take up.
Shedding: Separating the warp yarns into two layers by lifting and lowering the shafts, to form a tunnel known as the ‘shed’.
Shredding
Picking Passing the weft yarn (pick) across the warp threads through the shed.
Picking
Beating-up:
Pushing the newly inserted weft yarn back into the fell using the reed.
Beating-up
Let off: The warp yarns are unwound from the warp beam during the above three processes.
Take up: The woven fabric is wound on the cloth beam during the above three processes.
The primary motions can further be divided as shedding, picking and beat up motions. The shedding opens the warp sheet into layers to facilitate passage of shuttle. The picking motion causes the shuttle carrying weft to be propelled from one end of loom to another. The beat up motion lays the previously laid weft to the fell of the cloth. The secondary motions comprise of take up and let off motions. The take up motion helps to wind the cloth on to the cloth roller and also influences the pick density in the cloth. The let off motion helps to let the warp from the weaver’s beam at an uniform rate thus maintaining the warp tension constant throughout the weaving process.
The auxiliary motions consist of the warp stop motion, weft stop motion and warp protector motion. The warp stop motion is used to stop the loom in the event of warp breakages. This is necessary to prevent