Carding room equipment can traditionally be broken down into three machines (or sometimes just two, when the raw material requires less intensive treatment) and a number of drums that is determined by the type of processing being carried out.
The carding action is repeated a number of times on each of the machines, thus, by the time they are delivered as a web, the fibres have undergone a considerable number of processing stages, which have left them clean and reasonably parallel with one another, even though they are undoubtedly shorter. A compromise has to be reached between the need to open the tufts and the need not to impoverish or excessively shorten the fibres and it is this compromise that, for each raw material, determines the most opportune number of machines and drums to be used in processing.

Fig. 1 Automatic web conveyor with underground belt

In the woollen spinning cycle, the basic equipment, of which a number of variants exist, is made up of three machines: the first is called the breaker card, the second the cross card and the third the divider card. An automatic conveyor links the various machines, guaranteeing continuity of production and making carding a single process, albeit one characterised by repeated, increasingly thorough operations.

By means of an underground belt, the automatic conveyor (Figure 1) plucks the web as it leaves one carding unit and feeds it to the next: during this operation, the inclination of the fibres can change by up to 90° in relation to the feeding direction.