High-speed video graphic study of filament-core yarn spinning

One of the challenges in spinning fine-count core yarns is to achieve a perfect coverage of the core, especially when the filament core comprises a large proportion of the yarn. Any uncovered parts of the core will appear on the yarn surface as periodical defects, known as the barber-pole effect. The main tool available for spinners to improve yarn coverage (i.e. reduction of barber-pole effect) is optimising the relative roving and filament feeding configuration at the entrance to the yarn-forming zone. Using high-speed video photography, we investigated the formation of the barber-pole effect for several feeding configurations and the use of a false-twisting device. Core-yarn coverage could be improved by applying false twist in the yarn-formation zone. The direction of the false twist relative to the final twist imparted by the ring spindle was found to be critical to the improvement of the resultant core-yarn coverage. The coverage of core yarns produced in the trials was evaluated using an objective method based on a fast Fourier transform (FFT) algorithm. The objective assessment method is also described.