Rotor open end spinning - Production of Fine Rotor Spun Yarns

•Selection of raw materials : the selected cotton fibres should have following fibre properties:
–A] average fibre fineness = 1.7 dtex;
–B] effective fibre length = 32 mm.;
–C] fibre breaking length = 26-28 km. ;
–D] percentage of ripe fibres in excess of 80 %.
•The requirements of sliver preparation : sliver preparation should be done keeping in mind that the impurity level in fed slivers could not exceed 3mg/g of sliver.
• The more parallel the fibre orientation in the sliver , the better will be the fibre arrangement in the rotor groove & ultimately in the yarn.
• This means a minimum two draft passages , possibly three , if combed sliver is used.
• Special attention should be paid to the careful mixing .
• The number of doublings in the drafting passages are more significant.
• Fine slivers are readily subject to the draft faults such as the splitting of the web or licking up of of fibres which ruins the desired final assembly of the fibre mass.
• Hence the number of draft passages has to be limited to the point beyond which splitting could occur.
• For the same reason , the delivery speed of drawframe must be reduced for very fine slivers .
• Speed should not exceed 300 m/min. For a sliver linear density of up to 3 ktex, & care should be taken in coiling the sliver into sliver cans.