The friction spinning machine (Figure 1) operates on the basis of a principle of mechanical/aerodynamic spinning.
Being an open-end spinning machine, it effects direct transformation of sliver into yarn and delivers, at high speed, very large packages.

A rotating carding cylinder (1) breaks up the sliver applying a high draft between the entry (2) and the clothed surface of the cylinder itself. Thanks to a strong pneumatic suction effect (3), which increases the draft, the fibres are detached from the cylinder and transferred along the nip generatrix of the pair of spinning cylinders (4).

Fig. 1 Friction spinning machine

These are perforated and exert a suction effect on the fibres, which become twisted due to the friction effect and the torque imparted by the two cylinders, which have the same direction of rotation. The yarn is formed from the inside outwards by superimposition of the individual fibres, which, ultimately, become twisted round one another and strongly bound together. The yarn leaves the nip area of the two cylinders, parallel with their axis of rotation, and is then wound onto cylindrical packages at a rate of around 250-300 m/min.
The friction spinning method, while creating cohesion of the material only with a rather high number of fibres in the cross section (yarn count ranging from 3 to 10 Nm), is not as influenced by the characteristics of the fibre as all the other types of spinning. It allows the processing of natural or man-made fibres with counts ranging from 3 to 15 dtex and lengths of 5-100 mm: compared with traditional spinning machines, these machines clearly benefit from using heterogeneous, even regenerated, materials.
Furthermore, the possibility of using different types of filament as the core means that the yarn is quite strong. In order to obtain particular fancy effects, the spinning machine can be fed with slivers of different colours and materials. Within the maximum admissible loading limits (30 ktex), it is possible to feed various slivers (for example 5 6-ktex slivers), whose fibres will be arranged coaxially, creating a layered effect. Yarns can thus be constructed with the shortest and weakest fibres in the middle and the longer and the more valuable fibres at the outside or with whatever colour effect you like.
An experiment is currently being carried out to verify the possibility of using slivers originating both from cotton cards and from sets of carding cylinders with sliver delivery without the divider and from the worsted wool cycle.

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