WOOL COMBING  After worsted carding the wool sliver is processed through a number of gill boxes before combing  Gilling improves fibre alignment and removes hooks to some extent.  Wool noil vary from 5%-18%

Rectilinear Wool Combing [Detaching rollers are mounted on a moving carriage] a)Feed sliver preparation :  Odd number of processes (usually 3 gill stages) between card and combing [in cotton even number]  Majority hooks are in trailing (in cotton-> leading) - To minimize fibre breakage and noil extraction (due to longer fibre)

Side elevation of a rectilinear wool comb A- feed rollers B- feed grills C- upper nipper D- lower nipper E- cylinder F- brush on upper nipper H- shovel plate J- top comb K- detaching rollers L- counter sword M- top sword N- sliver supporting apron P- noil brush R- feed grid S- air suction duct (as an alternative L and M)

1.Feeding  Nippers open – feed roller (A) and feed gill (B) feed a fringe of fibres  Shorter feed for more burry wool –longer feed for long wools  Length of feed determines the production rate. Not in cotton comber Rectilinear wool comb cycle of operations

2.Initial combing (Fig. a and b)  Nippers C & D close  Lower the fibre fringe into the pins of the cylinder E.  For burry wools a de-burring blade G may momentarily push the fibres down into last few fine rows of pins [not in cotton comb] (a)(b)

 The feed gill (B) rises and moves back along with the feed grid (R), before being lowered ready for the next feeding cycle.  When the feedings are of leading hooks direction, for long wool fibers - both the ends of hook may be held by nippers, while the loop is broken by the cylinder pin. - When the hooks are trailing - less fibre breakage opposite to cotton comb

 Cylinder Diameter 150 mm and carries about 20 comb bars - Initial rows -> thicker and wider pins - last rows -> thinner and closer.  1 st row -> 4 pins/cm, 1mm diameter  Last row –> 26 pins/cm, 0.38 mm dia.

3.Final combing  The nippers C & D rise up and open the shovel plate H, moves forward between the open nippers ( normally not in cotton comber ) - supports the fringe as top comb, J, descends  The detaching rollers, K, draw the fringe of fibres away  Top comb has - 26 pins/cm - rectangular cross-section - pins 0.3mm x 0.7mm for merino wool.

Only for wool comb (Not in cotton comb)  To enable long fibre lengths to be drawn away, the detaching rollers, K, are usually mounted on a carriage - Which moves away from the nippers at the same time as K rotate to withdraw the fringe  In some wool comb, the counter sward (L) rises to support the fringe in the top comb, J, [Fig. c] (as the detaching roller K returns)  For very long fibre, the drawing- off is assisted by the top sward, M, moving down [Fig. d] - alternatively suction dust ‘S’ (earlier figure) is used in place of L and M. (c) (d)

4.Sliver formation : [Fig. e & f]  After complete drawing-off – the carriage starts to move towards the nippers – the detaching rollers K, recoil to feed the tail ends of the previous fringe.  As the carriage approaches close to the nippers, the detaching rollers, K, stop rotating. - Overlap of leading end of the new fringe with the trailing end of the previous fringe.  Then the earlier processes repeat. (e) (f)

Noble combing  Separates noil from top  Wool from punch balls A is drawn from the boxes by knife B, lifted from the pins at C and then pressed onto the pin by brush F where the large D and small E circles are closest.  As the pins separate by the rotation of the circles, two fringes are formed.

 The fringe on the large circle is combed by the pins of the small circle and conversely.  At G and H the fringes are drawn from the pins which comb the trailing ends of the fibers.

 The fibers from G and H are combined to form the ‘top’ sliver. Short fibers or noil remaining in the small circle at H, are removed from the pins by knives at J and are sucked away at K.  Short fibers remaining in the large circle are fed into the small circle at the next cycle of operations.

Hackling Hackling is the word used to describe the combing of fibres in flax processing (in processing other fibres the word combing is used). Hackling is carried out on hackling frames, as opposed to smaller combers used for wool or cotton. Hackling can be either discontinuous or, on more modern hackling frames, continuous. Feeding is done manually, in “hands” of 80 to 120 g, although automation is being developed.

Hackling In discontinuous combing, the clamps holding the strands circulate round the machine. In an upward and downward movement, the line flax is presented to a double set of combs. The combing action is vertical, the movement of the combs downward. The production of the machine is 60 kg/h

Hackling In continuous combing, the clamps are replaced by a conveyor belt circulating round the machine. The movement of the plates supporting the combs is also rotative, but the whole arrangement functions continuously. Production can reach 120 kg/h.

Hackling Combing waste, consisting mainly of short fibres, is called hackled flax. This is recuperated by doffers and collected in containers located underneath the machines. After combing, the sliver of line flax is automatically placed on a slanted table consisting of a series of moving transversal or gill bars. The strands are crossed to form a sliver. This sliver is fed to two calendar rollers and, after coiling, is pressed into packages to be stocked. The weight of the slivers varies between 20 and 40 g/m, depending on the yarn count to be obtained.