FAQ in Cotton Spinning-7

Q: What is the object of a speed frame
Ans: The object of a speed frame process is to reduce the sliver bulk to a diameter suitable enough fro the ring spinning frame to spin yarn.

Q : Why twist is required at the speed frame
Answer: Minimum twist is required to see that 1. The roving comes from the front roller nip on to bobbin through the flyer bore without being broken. b. The roving is nicely wound on to the bobbin. 3. that it does not suffer any creel stretch during unwinding in the next machine creel.
4. that the next machine can easily break the twist in the break draft zone.

Q. What is the function of paddle.
Ans: the paddle helps to produce compact and regularly built bobbins.

Q. How come the paddle always keeps pressed against the bobbin.
Answer: The paddle always keeps pressed against the bobbin due to the centrifugal force of the vertical solid bar.

Q. Why the threading slot is in the curved form.
Answer: This helps to prevent air drafts from entering the tube and disturbing the roving inside it. Besides it prevents liberation of fly.

Q: What causes winding of the twisted roving on the bobbin.
Ans: The differential surface speed between presser paddle and bobbin surface are responsible for winding of the twisted roving on the bobbin. Which is caused by differences in the flyer speed and bobbin speed.

Q: Why bobbin speed is reduced as the package diameter increases
Ans: As the diameter grows, bobbin surface speed increases although the revolutions per minute is constant. Therefore, bobbin speed is reduced in order to maintain the constant difference between the speeds of bobbin surface and paddle.

Q: What is 'flyer leading' and 'bobbin leading' case. Which is used in existing Speed frames.
Answer: S/F in which the flyer speed is higher than the bobbin surface speed is called 'flyer leading'. S/F in which the bobbin speed is higher than the flyer speed is called 'bobbin leading'. 'Bobbin Leading' case is used in existing S/F.

FAQ in Cotton Spinning -6

FAQ in Cotton Spinning-6

Q. What type of hooks are there in the card web ?
Answer: Bulk of the fibres in the card web are found to have hooks at their rear ends, and they are termed as trailing hooks.

Q. What type of hooks are removed at the drawframes.
Answer: Hooks are preferentially removed when they are presented in the drafting field in trailing direction.

Q. What is doubling. How does this affect regularity of a sliver.
Answer: Doubling is feeding more slivers together into the drafting zone. It improves the uniformity of sliver.

Q. Why we cannot offer a high draft in one go.
Ans: The resistance offered by the disorderly state often results in a greater unevenness in the drawing material.

Q. What can be the drawbacks of excessive parallelisation.
Ans: Slivers with high parallelisation become soft and their withdrawl from cans at later stages results in excessive creel breakages.

Q. What is roller slip
Ans: Top rollers are no positively driven. They are made to bear against the bottom fluted rollers with a suitable weighting arrangement. The motion transmission to the top roller is through the bulky sheet of fibres. Thus the speed of top roll is not the same as botton roll. This fall in speed of top roller is termed as roller slip.

Q. what will happen due to roller slip
Answer: The roller slip produces characteristic drafting waves or unevenness characeristics.

Q. What is a drafting wave
Answer: The irregular motion of short fibres between pairs of rollers give rise to a wave like formation that is known as drafting wave.

Q. What is the principle applied in roller setting over 44 drafting system.
Answer:
Front and second pair= effective length + 1/8 "
2nd and Third pair= eL+ 1/8"+1/8"
3rd and Back Pair= eL+1/8"+1/8"+1/8"

FAQ in cotton spinning-5

FAQ in Cotton Spinning-5

Question: What is the function of calender rollers.
Answer: The function of calender rollers primarily is:
a. To draw the web away from the doffer at a uniform rate as fast as it is stripped.
b. It exerts sufficient pressure on the sliver in order to reduce the bulkiness of this sliver.

Question: How diameter of trumpet hole varies with the thickness of the sliver.
Answer:

Diameter of hole in inches= constant x sqrt (grains/yard of sliver)

constant= 0.022

Question : How does the setting to the following pair of card points affect the quality of sliver produced.
Answer:
Taker in to cylinder: wider settings: creates neps and licker-in gets covered with fibres.
Back Plate to cylinder: wider setting causes fly to blow between flats.
Flats to cylinder: Closer settings gives better quality.
Front Plate to cylinder: closer setting-> reduces the weight of flat strip. wider setting-> results in heavier flat strips.
Doffer to cylinder: wider settings-> creates more neps as fibres go round the cylinder unnecessarily more times.
Feed plate to Licker in : wider settings-> lap is plucked without sufficient opening. So web quality is reduced.

Question: What are different types of carding wastes and their constituents
Answer: Licker- in waste-> short fibres, trash.
Flat Strips-> cotton fibres (short)
Stripping waste ( on cylinder and doffer wire)-> short fibres and trash

Question: Why flexible wire clothing is preferred over metallic wire clothing for running long fibres.
Answer: It is observed that flexible fillet has a more gentle carding action and gives lesser damage to good fibres.

Question: Why draw frame is needed
Answer: The fibres in a card web lie haphazardly criss cross to the web. Besides, fibres have either one or both end bent into the form of hooks. These haphazard fibres are required to be straightened and parallelised to the possible extent, also evenness and regularity of sliver is improved.

Process Control in Cotton Mixing

Process Control in Cotton Mixing

These two lectures answer the following questions:

1. How can I decide about cotton mixing for denim.

2. How can I decide about cotton mixing for making knitted fabric.

3. What is information required for an optimum cotton mixing.

4. What is an ideal cotton mix.

5. What are the steps to create an optimum cotton mix.

6. What are the four components of yarn quality. How each of these is affected by fiber quality.

7. What values of yarn quality parameters can be obtained from a cotton mix of particular fiber attribute.

8. For some pre specified values of yarn characteristics, what are the average values of fibre attributes that we should in cotton mix.

9. What are the various problems due to cotton mixing vairations, case study of fabric barre.

The answers to the above questions will be found here.