In this case, the rovings are not very cohesive or strong, therefore drafting must necessarily be very reduced (usually carried out at rates of between 20% and 50%) and supported by special fibre control devices. The shorter length of the raw material does not generally allow the fibres to be nipped by the pair of feeding cylinders or by the delivery cylinder, therefore resulting in a high percentage of floating fibres. Indeed, very short fibres do not fit the ideal pattern of behaviour within the draft range (whereby a fibre, nipped by its end by the pair of feeding cylinders, moves forward within the draft range controlled by contiguous fibres until it reaches the nip point of the pair of delivery cylinders, where it undergoes an acceleration), because floating fibres tend to change speed in an uncontrolled and premature manner, drawn by friction by those that the cylinders have already trapped. This is the cause of defective drafting, to which remedies can be sought in two ways:

1. through the adoption of drawing rates that are very low in relation to the length of the fibres
2. by carrying out, using appropriate devices, effective fibre control.

The so-called false twist draft is made up of a rotating organ, through which the roving runs, inserted in the draft range, close to the delivery cylinders. In a static situation, the roving would, in this way, receive false twists, that is to say in the opposite direction downstream and upstream of the rotating element. During motion, however, the situation that emerges is quite different, in that twisting is distributed and remains only in the stretch between the feeding cylinders and the point of rotation, while in the part that follows, as far as the drafting cylinders, twisting disappears, leaving the roving weaker and thus subject to breaks: this is why the rotating element is positioned as close as possible to the drafting cylinders. Drafting and twisting is a perfectly valid procedure for fibres of a certain length, while for shorter ones it needs to be integrated with the drafting-laminating unit, which allows good control of the fibres, preventing them from floating. The control devices must guarane the running of longer fibres as well, thereby effecting drafting in ranges of adequate width.

One valid solution is that of a pressure roller with high circumference, on which the fibres can assume a stable arrangement.
When wanting to apply a high draft ratio, thereby obtaining good adjustment of the roving, a draft range with a false-twisting device can be used, completed by a second range with a laminating unit: integration of these two systems makes it possible to increase the draft, and to achieve a stable value and stable results (Figure 1)

Fig. 1 Draft range with false twist followed by a range incorporating a laminating unit

In reference to the figure, the total draft to which the roving is submitted is calculated as follows
S total = S C = S A x S B