Desenvolvimento de um processo de recuperação de louça sanitária através da tecnologia laser

• Autor(a) principal: Costa, Rúben Daniel Fernandes de Sousa
• Data de Publicação: 2021
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.22/18920
• topic: Sanitary ware; Laser technology; Defects; Pinholes; Cracks; Louça sanitária; Tecnologia laser; Defeitos; Picadas; Fissuras

The ceramic sanitary ware industry is widespread all over the world. It employs thousands of people and, consequently, has a high financial impact on the global and national economy. The factories associated with this industry are vital in the 21st century as they have a daily production of the most diverse sanitary ware products, which refer to a higher level of comfort for the population. Due to these important items, the words quality and innovation are always present and, consequently, multifunctional teams work incessantly on their continuous improvement. Over the years, some changes have been made in the sanitary ware manufacturing process in order to achieve maximum efficiency. However, due to factors inherent to the manufacture of these products, at the end of the production line, there are defects that prevent a small percentage of them from being sold, as they do not reach the required quality. In order to promote a sustainable economy of resources for the company, it avoids products without the required quality level to be submitted to a new complete production cycle, thus promoting their repair in a simpler and more effective way. With the implementation of laser technology for the recuperation of sanitary ware, replacing the refiring process in the kiln, it is estimated that 9 € will be saved per product, on 5% of an annual production rate of 200,000 pieces. Laser technology, along with its numerous and different applications in the industry field nowadays, has all the means to be capable of performing a correct ink fusion on the defects which appear on ceramic sanitary ware materials, reason why it was tested for this project in a wide range of experimental tests that include provoked defects on ceramic tiles. Some analysis methods were also used, such as a colour difference reading to compare to the standard one (with a statistical approach), or the optical microscope and SEMEDS analysis, to complement the understanding of the results. Finally, two quality tests were performed, namely the autoclave and the acids, bases and staining agents’ tests, with the purpose of proving this method’s effectiveness. Accordingly, it was concluded that the best results, considering defects caused on a white coloured piece, are obtained with an ethyl alcohol-based ink, and the parameters to be used for the laser interaction are manual firing with a power between 50 and 70 W, and an interaction time of 1 to 3 firings of 10 seconds each without the use of any amplifying lens. These values apply for both pinholes and cracks, with a 50 W power and an interaction of 30 seconds being the best.