In this study, the tracer fiber method was used to determine the accelerated point distribution in both the break draft and main drafting zone of the drawing frame with varying different draft parameters. Viscose, cotton, and polyester slivers were used respectively. For the different parameters, the tracer fibers of known length were embedded in the single sliver strand, and measurements of their positions before and after drafting were taken. These measurements of the positions of tracer fibers before and after drafting were then used to deduce the nature of the fiber movement, thus determining the distribution of the accelerated points. The accelerated point distribution under different parameters was obtained. Gauss distribution was found to suitably describe the accelerated point distribution curve under different parameters used in this study. The pressure bar to some degree imparts a significant control of floating fibers within the drafting zone. The relationship between the sliver unevenness and the accelerated point variance (CV) was also discussed.

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Random fiber arrangement in slivers is the direct and intuitive factor resulting in sliver limit irregularity. In this study, by simulating the fiber arrangement in slivers, the effect of fiber configuration on sliver limit irregularity is investigated. The tracer fiber technique was employed to ascertain fiber straightness and the incidence of different fiber configurations in carded slivers. It is observed from the results that the majority of fibers are hooked in the carded sliver. It is fiber straightness rather than hook type that affects the sliver limit irregularity more; with the increase of fiber straightness, the sliver limit irregularity decreased. In addition, the simulation proposed in this study can not only portray fiber arrangement in slivers more practically, but also present sliver limit irregularity more accurately compared with the method mentioned in previous studies.

The dynamic motion of floating fibers in the drafting process, which can be characterized by fiber accelerated points, has an important effect on the sliver or yarn quality. In this study, the fiber accelerated point during the roller drafting process has been tested with an improved method. In this method, tracer fibers and standard tracer yarns of known length were embedded into the sliver in groups. By adjusting the length and fineness of the standard tracer yarns, it was possible to determine the nip line of the front roller dynamically. Therefore, the fiber accelerated points can be obtained in a continuous drafting process without an external sensor, which is simpler and more convenient, and avoids the experimental error caused by the drawing frame shutdown during the experiment. Based on this method, the effects of the drafting parameters and sliver properties on the fiber accelerated point in the roller drafting process have been investigated. In addition, the coefficient of variance of the sliver ( CVFAP) caused by the fiber accelerated point variation during the drafting process was also calculated. A comparison has been made between CVFAP and the standard deviation of the fiber accelerated points. It is found that a fairly good agreement between these two is seen, and this agreement can also evidence the accuracy of experimental results about the fiber acceleration point.