•Selection of raw materials : the
selected cotton fibres should have following
–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
• 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
• 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.