Several slivers are combined. Each sliver will have thin and thick spots, and by combining several slivers together a more consistent size can be reached. Since combining several slivers produces a very thick rope of cotton fibres, directly after being combined the slivers are separated into rovings. These rovings (or slubbings) are then what are used in the spinning process.
Draw frame is a machine for combining and drawing slivers of a textile fiber. Drawing is the operation by which slivers are blended, doubled and leveled. In drawing slivers are elongated when passing through a group of pair rollers, each pair is moving faster than previous one.
One of the main tasks of draw frame is improving evenness.
To obtain an optional value for strength in the yarn characteristics, the fibers must be arranged parallel in the fiber strand.
By merging different fibres together for instance cotton and polyester to get variations like: 65% Cotton 35% Polyester. The weight of sliver very important to get correct blending of fibres when feeding the draw frame with cans of sliver in Tex (the weight in grams per 1 kilometer [1000 meters] of yarn).
Dust is steadily becoming a greater problem both in processing and for the personnel involved. It is therefore important to remove dust to the greatest practical extent at every possible point within the overall process.