As shown in Fig. 28, a drawframe sliver fed from a can (1) is passed to a drafting arrangement (2), where it is attenuated by a draft in the range of 100 - 200. The fiber strand delivered then proceeds to two air jets (3 and 4) arranged directly after the drafting arrangement. The second jet (4) is the actual false-twist element. The air vortex generated in this jet, with an angular velocity of more than 2 million rpm, twists the strand as it passes through so that the strand rotates along a screw-thread path in the jet, achieving rotation speeds of about 250 000 rpm. The compressed air reaches the speed of sound when entering the central canal of the false-twist element. Since the axial forces are very low during this rotation, only low tensions arise in the yarn.
The ability of the vortex to impart torque is so high that the turns of twist in the yarn run back to the drafting arrangement. The fiber strand is therefore accelerated practically to full rotation speed as soon as it leaves the front roller. The edge fibers which ultimately bind the yarn together by becoming wrapping fibers are in a minority. For process reasons, they do not exceed about 5% of the total yarn mass. These edge fibers exhibit relatively few turns of twist in the same direction as the false-twisted core fibers or can even be slightly twisted in the opposite direction. This is partly ensured by causing the strand to emerge from the nip line in a broadly spread form, but mainly by generating in the first jet (3) a vortex with an opposite direction of rotation to the vortex in the second jet (4).
This first vortex is in fact weaker in intensity than the second and cannot really affect the core fibers, but can grasp the edge fibers projecting from the strand at one end. Since the first vortex acts against the twist direction generated by the second jet, it prevents the edge fibers from being twisted into the core or even twists them in the opposite direction around the core fibers. As the strand runs through the second jet, the following occurs.
The turns of twist generated by the jet (4) are canceled in accordance with the false-twist law. The core fibers, i.e. the vast majority, no longer exhibit any twist; these fibers are arranged in parallel. On the other hand, the edge fibers (which previously exhibited no twist, relatively little twist, or even twist in the opposite direction) receive twist in the direction imparted by the jet (4), as determined by the law of false twist; they are therefore wound around the parallel fiber strand. They bind the body of fibers together and ensure coherence. A twist diagram prepared by Dr. H. Stalder  demonstrates this twisting procedure (see Fig. 29).
The resulting bundled staple-fiber yarn passes from the take-off rollers (6 in Fig. 28) through a yarn-suction device (7) and an electronic yarn clearer (8) before being wound onto a cross-wound package (9).
The two nozzle air-jet spinning system represents a very interesting process, which has already been introduced into practical operation with some success.