Almost all manufacturers of blowroom machinery now offer dust-removing machines or equipment in addition to 
opening and cleaning machines. However, dust removal is not an easy operation, since the dust particles are completely enclosed within the flocks and hence are held back during suction (because the surrounding fibers act as a filter). Since, as shown by Mandl [4], it is mainly the suction units that remove dust (in this example 64%), dust removal will be more intensive the smaller the tufts.
It follows that dust elimination takes place at all stages of the spinning process. Fig. 5 shows Mandl’s figures for the various machines.
Fig. 5 – Dust removal as a percentage of the dust content of the raw cotton (A) at the various processing stages (B): 1 - 5, blowroom machines; 6, card; 7, drawframes; (a) filter deposit; (b) licker-in deposit; I, dust in the waste; II, dust in the exhaust air.
