Disc spinning is a new spinning technique that is still under investigation in many research institutes and universities. It is not yet a commercial system, although it is promising. The appearance of the outer layer of produced yarns is similar to that of ring spinning, but is produced at higher rates. It includes the major spinning stages such as fibre opening, feeding to the forming zone and yarn consolidation by twisting, then yarn winding. Opened fibres are condensed on the outer surface of a rotating screened surface disc and simultaneously twisted by using an external twister. Air suction acts through a slit located just beneath the screened surface at a certain angle that controls the laying angle of the fibre bundle on the screened surface. The formed yarn is then drawn at a predetermined angle with respect to the slit direction. It is suggested that both slit angle and the direction of the withdrawal of the yarn during its formation with respect to the slit affect fibre extent on the forming zone and, accordingly, yarn properties. Papers about this new technique are limited, especially those considering the effect of design parameters on fibre straightening during yarn formation. In this article, parameters expected to affect fibre extent in the forming zone during yarn formation were suggested and treated theoretically to maximise fibre straightening during yarn formation.
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The ease of accomplishing a tight knot in a rope depends mainly on the bending resistance of that rope, hence the bending behaviour of ropes becomes a matter of considerable importance. Reducing the bending resistance of ropes, while retaining their other physical and mechanical properties unchanged is a demand of rope consumers. Unfortunately there is no standardised method to measure the bending resistance of ropes. The bending resistance as a mechanical property depends on many factors, such as the type of material used, the processing methods, and the technical specification of the rope. In the present work, four factors were subjected to study, these being: filament denier twist in the primary strand, twist in the final strand, and percentage distribution of filament between core and sheath. A simple method, similar in principle to that used in the Shirley Fabric Stiffness Tester, was used to measure the bending length of polyethylene ropes. A simple model was derived to calculate the bending resistance of ropes. Multiple regression analysis was used to determine multiple correlation factors, degree of contribution of each factor to the measured properties, and its significant levels. Surface plots are used to demonstrate the shape of the effect of the factors that have significant effects.
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