Tuesday, 23 September 2008

FAQ in cotton Spinning-9

FAQs in Cotton Spinning

Q. What are the objects of ring spinning
Answer: There are three objects of ring spinning:
1. To draw the roving to the desired degree of fineness.
2. To impart sufficient twist to the emerging strand of fibres to from continuous yarn
3. To wind up the spun yarn into some convenient package form.

Q. What is the object of twist in Ring frame
Ans: The object of twist is to form a yarn with sufficient strength.

Q. Why every spinner wants to produce a yarn with as low twist as possible
Ans: Imparting twist consumes power, it also leads to low production. Also in untwisted from strength of yarn is about 30% more than in twisted state. Cloth manufactured bya low twist yarn tends to be fuller, stronger and more durable, Also dye absorption is better in low twisted yarns.

Q. How fiber length is related to twist
Ans: Longer the fiber, lesser is the amount of twist required. Frictional force increases with greater fibre length and as such there is more clinging power.

Q. How is fiber diameter is related to twist.
Answer: finer the fiber, more is the surface area available for clinging, thus more is the clinging power, hence lesser is the amount of twist required.

Q. How yarn diameter is related to twist ?
Ans: Coarser the yarn, more are the number of fibres per cross section and thus lesser is the required twist.

Q. How twist is related to yarn contraction ?
Ans: When twisted, the fibres take helical shape, that is, they get bent. Owing to this bending, there is a reduction in the length actually delivered from the front roller nip. This reduction in length is called contraction.

Q. What are the directions of twist ?
Ans: There are two popular ways in which yarn is twisted. Right Hand Twist is formed when the spindle revolves in clockwise direction as viewed from top. RH twist is also called, warp way, Z-way or twist way. The Left Hand twist is fromed when the spindle revolves in Anti clock wise direction. LHT is also called weft-way, S-way, reverse way etc.

Q. What are the various conventions of twist directions used in cloth.
Answer: A cloth is supposed to be best if woven with warp twisted right way and weft twisted left way.

Q. Why we avoid S-twist on ring frames.
Ans: It is often difficult to get left hand piecers to attend the machine with S-way twisting.

Q. Why over twisted yarn is not preferred ?
Answer: When overtwisted, the yarn becomes unbalanced. The yarn contracts excessively and becomes poor in strength. the yarn becomes hard, stiff and wiry. It has a harsh feel and dull appearance. It caused a lot of trouble in weaving.

Q. Why overtwisted yarns sometimes are needed.
Ans: Overtwisted yarns are manufactured for some special purpose. 'crepes' and 'voils' are woven with overtwisted yarns.

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