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Abstract(s)
Atualmente o tecido industrial português enfrenta uma forte concorrência dos países onde os custos operacionais são significativamente mais baixos. O sector têxtil é dos que mais tem sofrido com esta evolução, sendo cada vez mais claro que apenas conseguirão sobreviver as empresas que diferenciarem os seus produtos ou serviços da restante oferta. Torna-se assim fundamental uma forte aposta na inovação, não só aquela que implica alguns investimentos e produz avanços tecnológicos, mas também aquela focada nos pequenos detalhes e na melhoria contínua dos processos do dia-a-dia. O processo de relaxamento e, principalmente, o de termofixação, são fundamentais para a conformidade do artigo, em termos de estabilidade dimensional, largura e gramagem. Estes processos são baseados em tratamentos térmicos, utilizando elevadas temperaturas para corrigir as tensões introduzidas aquando da produção do artigo, neste caso, a malha. Numa fase inicial são avaliadas as condições de entrada em produção dos artigos em estudo, malha jersey, composta por 95% de viscose e 5% de elastano. Os artigos estudados estão codificados por 992, 652 e 365. A segunda etapa passa por avaliar a influência do processo de relaxamento, em termos de estabilidade dimensional, gramagem e largura, e só depois foram alterados parâmetros de processo – normalização do processo de relaxamento. A terceira fase do projeto consiste em identificar as variáveis críticas do processo de termofixação e, posto isto, proceder à normalização do processo, tendo em conta, sempre, os resultados do artigo acabado, ou seja, nas condições de entrega ao cliente. Com a evolução do projeto, constatou-se que o principal benefício do relaxamento é reduzir significativamente os encolhimentos provocados na produção da malha. Obtém-se, em média, uma diminuição de 30% relativamente aos encolhimentos à teia e 19% relativamente à trama. Relativamente à termofixação, concluiu-se que os parâmetros de processo mais influentes são: temperatura, tempo de permanência, largura e gramagem obtida. Com o aumento 5°C na temperatura de termofixação, passando de 185°C para 190°C, obteve-se melhorias nas características do artigo acabado na ordem dos 5% à teia. Enquanto que o artigo termofixado a 185°C obteve-se encolhimentos médios à teia de -10% e à trama -4, o termofixado a 190ºC obteve encolhimentos médios de -5% á teia e -4% à trama. A normalização de processos é muito importante para que se garanta a reprodutibilidade das características dos artigos. É também uma importante ferramenta para diminuir a não-qualidade e desta forma os reprocessamentos internos – operação extras ao processo previamente estipulado.
At the moment, the Portuguese TEXTILE AND CLOTHING INDUSTRY faces strong a competition from the other countries where operating costs are lower. This sector has suffered a big evolution, and it is increasingly clear that only companies that differentiate their products or services from the remaining supply will be able to survive. Thus, a strong commitment to innovation is essential, not only the one that implies some investments and produces technological advances, but also that focused on the small details and the continuous improvement of the day-to-day processes. The relaxation process, and especially the thermofixation process, are fundamental for the conformity of the article, in terms of dimensional stability, width and weight. These processes are based on heat treatments, using high temperatures to correct the introduced stresses when producing the article, in this case the mesh. In an initial phase, the production conditions of the articles under study, jersey knit, composed of 95% of viscose and 5% of elastane are evaluated. The articles studied are coded by 992, 652 and 365. The second step was to evaluate the influence of the relaxation process, in terms of dimensional stability, weight and width, and only afterwards were changed process parameters - normalization of the relaxation process. The third phase of this project consists in identifying all critical variables of the thermofixation process and, therefore, normalizing the process, always taking into account the results of the finished article, that is, in the conditions of delivery to the client. In the course of the project, the main benefits to growth are the most provocative processes in the production of the knit. Gets, on average, a decrease of 30% in relation to the shrinkage in the web and 19% in relation to the plot. About thermofixation, it was concluded the most influential results processes are: temperature, residence time, width and weight obtained. With the 5° C increase in temperature to heat setting, passing for 185° C to 190° C, improvements in the features of the article over on the order of 5% to the Web. While the article thermoseted to ar 185°C average shrinkage obtained the Web of -10% and -4%, the thermoseted plot to 190°C obtained average shrinkage -5% to -4% to web and weft The standardization of processes is very important to ensure the reproducibility of the characteristics of the articles. It is also a tool to decrease not-quality. and in this way the internal reprocessing -extra operation to process previously stipulated.
At the moment, the Portuguese TEXTILE AND CLOTHING INDUSTRY faces strong a competition from the other countries where operating costs are lower. This sector has suffered a big evolution, and it is increasingly clear that only companies that differentiate their products or services from the remaining supply will be able to survive. Thus, a strong commitment to innovation is essential, not only the one that implies some investments and produces technological advances, but also that focused on the small details and the continuous improvement of the day-to-day processes. The relaxation process, and especially the thermofixation process, are fundamental for the conformity of the article, in terms of dimensional stability, width and weight. These processes are based on heat treatments, using high temperatures to correct the introduced stresses when producing the article, in this case the mesh. In an initial phase, the production conditions of the articles under study, jersey knit, composed of 95% of viscose and 5% of elastane are evaluated. The articles studied are coded by 992, 652 and 365. The second step was to evaluate the influence of the relaxation process, in terms of dimensional stability, weight and width, and only afterwards were changed process parameters - normalization of the relaxation process. The third phase of this project consists in identifying all critical variables of the thermofixation process and, therefore, normalizing the process, always taking into account the results of the finished article, that is, in the conditions of delivery to the client. In the course of the project, the main benefits to growth are the most provocative processes in the production of the knit. Gets, on average, a decrease of 30% in relation to the shrinkage in the web and 19% in relation to the plot. About thermofixation, it was concluded the most influential results processes are: temperature, residence time, width and weight obtained. With the 5° C increase in temperature to heat setting, passing for 185° C to 190° C, improvements in the features of the article over on the order of 5% to the Web. While the article thermoseted to ar 185°C average shrinkage obtained the Web of -10% and -4%, the thermoseted plot to 190°C obtained average shrinkage -5% to -4% to web and weft The standardization of processes is very important to ensure the reproducibility of the characteristics of the articles. It is also a tool to decrease not-quality. and in this way the internal reprocessing -extra operation to process previously stipulated.
Description
Keywords
Elastano Viscose Malha jersey Relaxamento Termofixação Estabilidade Dimensional Elastane Viscose Relaxation Knit jersey Thermofixation Dimensional stability