O corte de materiais por disco abrasivo é um dos processos que apresentam as melhores características de economia, eficiência e rapidez sendo muito utilizado no meio industrial. Fatores como porcentagens e homogeneidade da mistura dos componentes, tamanho, forma (abrasividade), tenacidade e dureza dos grãos abrasivos, tipos de ligantes e de abrasivos, velocidade de corte e velocidade de mergulho influenciam na segurança, no desempenho e comportamento da operação. Este trabalho apresenta um estudo sobre a influência da dureza dos discos abrasivos no desempenho do processo de corte em operações do tipo remoção a seco. O aumento da dureza dos discos propiciou um aumento da força tangencial de corte e da relação G, devido à mais forte ligação entre o grão e o ligante no compósito. Os resultados mostram que a dureza dos discos abrasivos afeta a economia, pois influencia na vida útil dos discos abrasivos em termos de números de cortes proporcionados; a produtividade, pois está relacionada com o número de trocas de discos desgastados; os esforços necessários para a operação, pois estão relacionados com as forças tangenciais de corte.

The cutting of materials by abrasive discs is one of the processes that present the best characteristics of economy, efficiency and speed, thereby being very used in the industrial way. Factors as percentages and homogeneity of the mixture's components, size, shape (abrasive strength), toughness and hardness of the abrasive grains, types of binder and materials, disc speed and cutting speed affect the safety, performance and behavior of the cutting operation. This work presents a study about the influence of abrasive disks hardness on their performance to cut-off ductile materials without cooling. The increase of the hardness of the disks resulted in an increase of the tangential cutting force and G ratio, due to stronger bonding between the abrasive particles and the binder in the composite. The results show that the hardness of the abrasive discs affects the economy, because it influences the useful life of the abrasive discs (the numbers cuts provided); the productivity because it determines the number of replaced discs; the necessary efforts for the operation because it is related with the tangential cutting force.

Energy consumption, air pollution and industrial waste have received special attention from public authorities in recent years. The environment has become one of the most important subjects in the context of modern life, for its deterioration impacts the quality of life populations. Driven by pressure from environmental agencies, politicians have drawn up ever stricter laws aimed at protecting the environment and preserving energy resources. All these factors have led industry, research centers and universities to focus their efforts on researching alternative production processes, creating technologies to minimize or avoid the production of environmentally aggressive residues. Up to a few years ago, the main objective of manufacturing plants was to produce goods aimed at satisfying technological and economic aspects. Green, or "dry" machining and Minimum Quantity Lubricant (MQL) machining have caught the attention of researchers and technicians in the area of machining as an alternative to traditional fluids. Thus, this work proposes to explore the MQL concept in the grinding operation. Although its advantages allow one to predict a growing range of applications for MQL, the variables of influence to be considered and the effects on the results of the process have so far been little studied. Grinding involves several input parameters but, to date, little attention has been focused on the form and quantity of cutting fluid applied to the process. The condition and rate of cutting fluid applied directly influences some of the process's output variables. This work, therefore, analyzes the behavior of the MQL technique under different lubrication and cooling conditions, developing an optimized fluid application methodology based on the creation of a special nozzle through which a minimum amount of oil is pulverized in a compressed air stream. The evaluation of the technical performance of MQL in grinding, using aluminum oxide and superabrasive CBN (cubic boron nitride) grinding wheels, consisted of an experimental analysis of the behavior of the tangential cutting force, G ratio, roughness and residual stress. The results presented herein allowed us to evaluate the behavior of the MQL technique in the grinding process, thus contributing toward an environmentally friendly technology.

O presente trabalho apresenta uma metodologia confiável e de execução rápida para a avaliação do desgaste abrasivo entre as cerâmicas Duceram e Vita nas resinas compostas Z-100 e Charisma. Estes materiais são amplamente utilizados nos consultórios e clínicas dentais para restaurações funcionais e estéticas dos dentes. Para avaliar o desgaste abrasivo entre os materiais, um disco dinâmico revestido com porcelana foi utilizado sobre um disco estático revestido com resina. Os resultados indicaram que a cerâmica Vita apresenta desgaste inferior a Duceram nas resinas analisadas.

This work presents a fast and trustworthy methodology for the evaluation of the abrasive wear between the ceramics Duceram and Vita and the composites resins Z-100 and Charisma. These materials are widely used in dental clinics to restoration of function and aesthetics of the teeth. To evaluate the abrasive wear between the materials, a dynamic disk covered with ceramic was used contrary to a static disk covered with resin. The results showed that Vita presents an inferior wear against Duceram in the resins tested.