Rotor Spinning for Wool
- •The longer staple length of wool , its general coarseness as a fibre , the presence of the wool scales , burrs & remnant trash content, its crimp frequency , the greater sensitivity of wool with with respect to specific mechanical stresses causes troubles for rotor spinning of the wool fibres.
- • Because its lead to a larger rotor diameter , lower rotor speeds & comparatively high twist factors & also more rotor deposits.
- •Staple length should be less than rotor diameter.
- • Spinning is limited to minimum of 90-120 fibres in the yarn cross section.
- • There shouldn't be a residual fat content of 0.5-0.7% in the fed sliver. Also sliver should content fibres of low crimp frequency.
- •For this purpose back-washing in a solution of sodium bisulphite & drying under tension] should be carried out prior to spinning.
- • Purity of fibre stock is very important.
- •Stretch breaking is an alternative method for preparing the spinning stock. Normal tops may be used for rotor spinning if the staple length is reduced by stretch breaking .
- •The staple diagram can then be altered by breaking the longest fibres in several draft zones.
•Results have shown that all other things being equal, broken slivers can be spun with about 20% less twist than for carded slivers.
•The distance between the feed roller & opening roller has been increased by 40mm.
•To avoid damage to fibres.
•The opening roller has been widened.
•Pinned type opening rollers are used.
•The alternative opening process utilizes a fibre selector [it consists of a cylinder created by staggered lamellae, each of which takes the form of an equilateral triangle with rounded corners] in conjunction with a double-apron draft feed.
•The selector cylinder presses against a rubber covered roller & acts as a draft cylinder , applying very high draft ratios.
• The fibre end is nipped between the selector & rubber covered & is removed from the sliver without a hooked configuration.
• Rotor with a diameter of 90-100mm., V-shaped groove & without additional surface coatings were found to give best results. A smooth doffing tube is also recommended.
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