Write short notes on Hook fibres in carding Discuss why always a leading hook should be presented to the comber?
Give the percentage of leading and trailing hook in card sliver
What are the different types of hooks formed in a card?
Give their proportion of formation Following are the two types of hooks present in card sliver:
1. Trailing hook. 2. Leading hook.
The bulk of fibres as they leave the doffer are found to have hook at their rear end (back end) are 'Trailing Hooks" and the fibres are found to be hooked at their forward ends termed 'leading hooks'.
Proportion of the fibre hooks in the card sliver
Trailing hooks = 55 % Both ends hooked = 15%
Leading hooks = 15 % No hooks =15 %
Machine vibration, improper settings, and disturbing air current in the drafting zone have adverse effects and fresh hooks tend to appear. Hook formation tendency is proportional to the length as well as fineness characteristic.
Due to the natural reversal of material at each stage of processing, the hooks can be fed either as leading or trailing.
Major hooks as leading hook should be presented to comber, otherwise trailing hook increases the waste percentage at comber. The increase in waste is not because of the comber extracting more short fibre, but because of hooked long staple fibre go into waste.
Even number of passages (two or four machines) should be provided between carding and comber for presenting major hooks as leading to the comber. Similarly,
Odd number of passages should be provided between card & Ring frame to feed major hook as Trailing hook, to the Ring frame.
Effect of cylinder speed on hook formation and yarn quality. Count 44s; Doffer = 7 RPM. 50 grains/yard of sliver.