Desempenho da lubrirrefrigeração por MQL e limpeza da superfície de corte do rebolo na retificação de ferro fundido nodular
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Data
2022-05-18
Autores
Lopes, José Claudio
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A aplicação de ferro fundido nodular austemperado na indústria tem ganho destaque devido sua elevada resistência mecânica e fácil manufatura. Além disso, devido sua elevada fluidez, é possível fundir peças com dimensões próximas à final. Tais componentes podem necessitar de elevada precisão geométrica e dimensional, podendo ser corrigidos a partir do processo de retificação. Nesse processo, utiliza-se rebolos com diferentes grãos abrasivos e vários níveis de friabilidade, podendo estes interferir significativamente na qualidade da peça. Além disso, a elevada geração de calor é uma característica intrínseca do processo de retificação, sendo necessário a utilização de técnicas para mitigar o efeito. A lubrirrefrigeração abundante é uma técnica que aplica de dezenas a centenas de litros de fluido de corte por minuto, mas possui um passivo trabalhista e ambiental questionável; em alternativa, tem-se a técnica de mínima quantidade de lubrificante (MQL), aplicando poucos mililitros por hora ao passo que respeita a política sustentável internacional, mas com o ônus de baixo poder de refrigeração. Vários estudos comprovaram que a adição de água aos fluidos de corte utilizados na técnica de MQL tendem a melhorar significativamente as variáveis de saída do processo, podendo ainda ser otimizado a partir da técnica de limpeza da superfície de corte do rebolo (WCJ), na qual a inserção de ar comprimido na superfície de corte do rebolo contribui para minimizar o fenômeno de empastamento. O objetivo desta pesquisa foi combinar os respectivos parâmetros citados e avaliar as diferentes variáveis de saída do processo, nas quais foram analisadas rugosidade média aritmética (Ra) e rugosidade média (Rz), desvios de circularidade, desgaste do rebolo, emissão acústica, energia específica de retificação e microdureza. Assim, este estudo foi idealizado a partir da escassez de conteúdos sobre a friabilidade de grãos abrasivos na retificação de ferro fundido nodular austemperado. Para tanto, foram utilizados dois rebolos, um com grãos abrasivos menos friáveis e outro com elevada friabilidade, comparando-os ainda com diferentes técnicas de lubrirrefrigeração combinadas à aplicação de limpeza da superfície de corte do rebolo. Concluiu-se que o rebolo com grãos abrasivos menos friáveis se mostrou mais eficiente quanto ao acabamento superficial das peças, visto que o MQL diluído combinado ao sistema de limpeza produziu resultados muito próximos ao método de lubrirrefrigeração abundante. Além disso, foi evidenciada uma perspectiva de produção eficiente, podendo catalogar o funcionamento dos rebolos. Ao mesmo tempo, a pesquisa pode estabelecer uma relação em favor de sua aplicação, associada a técnicas sustentáveis e não agressivas ao meio ambiente e à saúde do trabalhador.
Applying austempered ductile iron in the industrial sector has gained prominence due to its high mechanical strength and easy manufacture. In addition, due to its high fluidity, it is possible to cast parts with dimensions close to the final. Such components may need high dimensional and geometric precision, corrected from the grinding process. In this process, grinding wheels with different abrasive grains and various levels of friability can be used, which can significantly interfere with the piece's quality. However, high heat generation is an intrinsic characteristic of the grinding process, requiring techniques to mitigate the effect. Flood lubri-cooling is a technique that applies tens to hundreds of liters of cutting fluid per minute, but it has questionable labor and environmental liabilities; alternatively, there is the technique of minimum quantity lubrication (MQL), applying a few milliliters per hour while respecting the international sustainable policy, but with the burden of low cooling power. Several studies have shown that the addition of water to the cutting fluids used in the MQL technique significantly improves the process output variables and can even be optimized from the wheel cleaning jet (WCJ), in which compressed air is inserted into the cutting surface of the grinding wheel, and it helps to minimize the clogging phenomenon. The purpose of this research was to combine the respective parameters quoted and evaluate the different process output variables, in which arithmetic average roughness (Ra) and average roughness (Rz), roundness deviation, grinding wheel wear, acoustic emission, specific grinding energy, and microhardness were analyzed. Thus, this study was envisioned from the scarcity of contents about the austempered ductile iron and abrasives grains friability in the grinding process. Hence, two grinding wheels, one with abrasive grains less friable and the other with high friability, were used, comparing them still with different lubri-cooling techniques combined to wheel cleaning jet application. It was concluded that the grinding wheel with less friable abrasive grains proved to be more efficient in terms of the workpiece's surface finish since the diluted MQL combined with the wheel cleaning jet produced results very close to the flood application. Besides, it was evidenced a production perspective efficient, having been able to catalog the functioning of the grinding wheels. At the same time, the research can establish a relationship in favor of their performance, associated with sustainable techniques that are not harmful to the environment or the employee's health
Applying austempered ductile iron in the industrial sector has gained prominence due to its high mechanical strength and easy manufacture. In addition, due to its high fluidity, it is possible to cast parts with dimensions close to the final. Such components may need high dimensional and geometric precision, corrected from the grinding process. In this process, grinding wheels with different abrasive grains and various levels of friability can be used, which can significantly interfere with the piece's quality. However, high heat generation is an intrinsic characteristic of the grinding process, requiring techniques to mitigate the effect. Flood lubri-cooling is a technique that applies tens to hundreds of liters of cutting fluid per minute, but it has questionable labor and environmental liabilities; alternatively, there is the technique of minimum quantity lubrication (MQL), applying a few milliliters per hour while respecting the international sustainable policy, but with the burden of low cooling power. Several studies have shown that the addition of water to the cutting fluids used in the MQL technique significantly improves the process output variables and can even be optimized from the wheel cleaning jet (WCJ), in which compressed air is inserted into the cutting surface of the grinding wheel, and it helps to minimize the clogging phenomenon. The purpose of this research was to combine the respective parameters quoted and evaluate the different process output variables, in which arithmetic average roughness (Ra) and average roughness (Rz), roundness deviation, grinding wheel wear, acoustic emission, specific grinding energy, and microhardness were analyzed. Thus, this study was envisioned from the scarcity of contents about the austempered ductile iron and abrasives grains friability in the grinding process. Hence, two grinding wheels, one with abrasive grains less friable and the other with high friability, were used, comparing them still with different lubri-cooling techniques combined to wheel cleaning jet application. It was concluded that the grinding wheel with less friable abrasive grains proved to be more efficient in terms of the workpiece's surface finish since the diluted MQL combined with the wheel cleaning jet produced results very close to the flood application. Besides, it was evidenced a production perspective efficient, having been able to catalog the functioning of the grinding wheels. At the same time, the research can establish a relationship in favor of their performance, associated with sustainable techniques that are not harmful to the environment or the employee's health
Descrição
Palavras-chave
Retificação, Friabilidade, Ferro Fundido Nodular Austemperado (ADI), Sustentabilidade, Mínima Quantidade de Lubrificante (MQL), Rebolos, Grinding process, Friability, Austempered Ductile Iron (ADI), Sustainability, Minimum Quantity Lubrication (MQL)