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Abstract(s)
Nestes tempos, os maiores desafios para a indústria são o aumento da taxa de produção e o aumento da qualidade, com o mínimo custo possível. Para aumentar a taxa de produção é necessário aumentar a velocidade com que se trabalha, mas no caso do torneamento implica uma maior geração de calor na peça e na ferramenta o que tem consequências negativas no acabamento da peça e na vida útil da ferramenta. Para permitir o aumento da taxa de produção sem perda significativa da qualidade superficial, utilizam-se, frequentemente, métodos de lubrificação e refrigeração, mas estes acabam por ser dispendiosos. É aqui que entra a quantidade mínima de lubrificação e os fluídos naturais de base biológica, por exemplo a água ruça, devido às suas propriedades renováveis, biodegradáveis, mais ecológicas, e ao seu baixo custo de produção.
A quantidade mínima de lubrificação consiste na pulverização de um fluído com um fluxo de ar comprimido, isto permite diminuir drasticamente as quantidades de fluídos utilizadas e materiais que seriam utilizados num outro tipo de lubrificação, sendo assim mais barata e mais ecológica.
Na presente dissertação foi realizado um estudo para a viabilidade da utilização de água ruça como lubrificante e refrigerante, através da quantidade mínima de lubrificação, substituindo óleos de corte. Para obter um termo de comparação foi estudada a rugosidade superficial, na maquinagem do aço DIN CK45. Para tal, foram realizados ensaios sem lubrificação, com lubrificação e refrigeração de água ruça e, finalmente, com um óleo de corte. Para obter a menor rugosidade foram analisados os efeitos de três parâmetros de corte durante o processo de torneamento sendo eles a velocidade de corte, velocidade de avanço e penetração.
Com o Método de Taguchi foi possível determinar a matriz dos ensaios experimentais realizados neste trabalho, foi assim construída uma matriz ortogonal L9 e, posteriormente, determinou-se a melhor combinação de parâmetros para a rugosidade superficial e para a taxa de produção. Após os ensaios realizados para as diferentes condições de lubrificação e refrigeração, faz-se a medição da rugosidade superficial. Segundo o Método de Taguchi conclui-se que a combinação 𝑉𝑐 = 315 [m/min], 𝑓𝑧 = 0,16 [mm/rot] e 𝑎𝑝 = 0,9 [mm] (ensaio 16) obteve o menor valor de rugosidade superficial (3,54 μm). Relativamente à taxa de produção a melhor combinação foi a utilizada nos ensaios 9, 18 e 27, onde os parâmetros são: 𝑉𝑐 = 315 [m/min], 𝑓𝑧 = 0,28 [mm/rot] e 𝑎𝑝 = 0,6 [mm]. Corresponde a uma taxa de produção de 52,92 cm3/min e uma razão S/N de 34,47 dB. Pode-se, também, concluir que as águas ruças têm potencial para ser utilizadas como fluído de refrigeração desde que associados a aditivos que diminuam a sua acidez e baixem o nível de bactérias.
In these times, the biggest challenges for the industry are the increase in the production rate and the increase in quality. In order to increase the production rate, it is necessary to increase the speed with which it works, but in the case of turning it implies a greater generation of heat in the workpiece and tool, which has negative consequences on the workpiece finish and tool life. To do this, lubrication and cooling methods are used, but they turn out to be expensive. This is where the minimum quantity lubrication and natural bio-based fluids come in, for example olive mill wastewaters, due to their renewable, biodegradable, more ecological properties, and their low production cost. The minimum quantity lubrication consists of spraying a fluid with a flow of compressed air, this allows to drastically reduce the amounts of fluids used and materials that would be used in another type of lubrication, thus being cheaper and more environmentally friendly. In this dissertation a study was carried out for the feasibility of using olive mill wastewaters as a lubricant and coolant, through the minimum quantity lubrication, replacing cutting oils. To obtain a comparison term, surface roughness was studied when machining DIN CK45. For this purpose, tests were carried out without lubrication, with olive mill wastewaters lubrication and cooling and finally with cutting oil. To obtain the lowest roughness, the effects of three cutting parameters during the turning process were analyzed, namely the cutting speed, feed speed and penetration With the Taguchi Method it was possible to determine the matrix of the experimental tests carried out in this work, an orthogonal L9 matrix was thus constructed and, subsequently, the best combination of parameters for surface roughness and production rate was determined. After the tests carried out for the different lubrication and cooling conditions, the surface roughness is measured. According to the Taguchi Method, it is concluded that the combination 𝑉𝑐 = 315 [m / min], 𝑓𝑧 = 0.16 [mm / rev] and 𝑎𝑝= 0.9 [mm] (test 16) obtained the lowest value surface roughness (3.54 μm). Regarding the production rate, the best combination was used in tests 9, 18 and 27, where the parameters are: 𝑉𝑐 = 315 [m / min], 𝑓𝑧= 0.28 [mm / rot] and 𝑎𝑝 = 0,6 [mm]. It corresponds to a production rate of 52.92 cubic centimeters per minute and an S/N ratio of 34.47 dB. It can also be concluded that olive mill wastewaters have the potential to be used as a cooling fluid as long as associated with additives that reduce its acidity and lower the level of bacteria.
In these times, the biggest challenges for the industry are the increase in the production rate and the increase in quality. In order to increase the production rate, it is necessary to increase the speed with which it works, but in the case of turning it implies a greater generation of heat in the workpiece and tool, which has negative consequences on the workpiece finish and tool life. To do this, lubrication and cooling methods are used, but they turn out to be expensive. This is where the minimum quantity lubrication and natural bio-based fluids come in, for example olive mill wastewaters, due to their renewable, biodegradable, more ecological properties, and their low production cost. The minimum quantity lubrication consists of spraying a fluid with a flow of compressed air, this allows to drastically reduce the amounts of fluids used and materials that would be used in another type of lubrication, thus being cheaper and more environmentally friendly. In this dissertation a study was carried out for the feasibility of using olive mill wastewaters as a lubricant and coolant, through the minimum quantity lubrication, replacing cutting oils. To obtain a comparison term, surface roughness was studied when machining DIN CK45. For this purpose, tests were carried out without lubrication, with olive mill wastewaters lubrication and cooling and finally with cutting oil. To obtain the lowest roughness, the effects of three cutting parameters during the turning process were analyzed, namely the cutting speed, feed speed and penetration With the Taguchi Method it was possible to determine the matrix of the experimental tests carried out in this work, an orthogonal L9 matrix was thus constructed and, subsequently, the best combination of parameters for surface roughness and production rate was determined. After the tests carried out for the different lubrication and cooling conditions, the surface roughness is measured. According to the Taguchi Method, it is concluded that the combination 𝑉𝑐 = 315 [m / min], 𝑓𝑧 = 0.16 [mm / rev] and 𝑎𝑝= 0.9 [mm] (test 16) obtained the lowest value surface roughness (3.54 μm). Regarding the production rate, the best combination was used in tests 9, 18 and 27, where the parameters are: 𝑉𝑐 = 315 [m / min], 𝑓𝑧= 0.28 [mm / rot] and 𝑎𝑝 = 0,6 [mm]. It corresponds to a production rate of 52.92 cubic centimeters per minute and an S/N ratio of 34.47 dB. It can also be concluded that olive mill wastewaters have the potential to be used as a cooling fluid as long as associated with additives that reduce its acidity and lower the level of bacteria.
Description
Keywords
Lubrificação Refrigeração Rugosidade superficial Torneamento Taxa de produção