Mapa da pilosidade H de fios de algodão em sistemas de fiação de anel/viajante trados por nitretação à plasma

Abstract

This experimental investigation concerning to cotton yarn quality was conducted in two different textile industries according to USTER® yarn quality benchmarks. The results of the Hairiness H of yarn samples representing each diary production were tested using ANOVA by means of Statgraphics® Centurion XVI statistical tool. A hairiness H map was designed and systematically constructed for evaluate the quality of NE 30/1 Cotton Carded Knitting Yarns produced during all the life of travelers running continuously at 28 m/s and 42 m/s in two ring spinning machines, with 528 and 1,480 spindles, so constituting two systems, A and B, respectively. Tribological abrasion tests were designed and performed in Laboratory at 3.5 m/s in order to simulate Hertzian contact pressures since severe to moderate range for simulate the contact zone of the ring-traveller system and analyze by Scanning Electron Microscopy their main wear mechanisms. Ion nitrided travellers were obtained by two different processing conditions, C and D, to compose lots of 100 nitrided travellers for A spinning machine system and 740 nitrided travellers (C and D schemes) for B system and were experimentally tested in comparison with conventional travellers. Periodical Surface Roughness, Rsm, and Nonperiodical Ra, Rq and Rz parameters of nitrided and conventional travellers, in the Position of Yarn Bath, i.e., the contact zone between the traveller and the yarn, were measured by Atomic Force Microscopy (AFM), in two conditions, new and worn after their service life. The Hairiness H Map developed in this thesis showed is a useful tool for a broad visualization of the traveller functionality, the relevance of its surface treating and the evolution of the surface roughness during its service life. The nitrided travellers demonstrated longer life and they produced NE 30/1 Cotton Carded Knitting Yarns with lower H hairiness that those obtained by conventional travellers.