Estudo da formação da aresta postiça de corte: suas influências sobre os parâmetros de usinagem

Abstract

There are a number of undesirable factors in the machining process that may influence in the quality of the final product. Among this range of factors, this paper focuses primarily on study the mechanism of formation of the built-up edge (BUE). To assist in the understanding of this study, was analyzed the necessary cutting conditions for the emergence of this phenomenon. Factors such as cutting temperature, cutting speed, workpiece material, the magnetic field, plastic flow, adhesion of the workpiece material on the tool edge and the appearance of microcracks in the workpiece, have proven their influences on the formation of BUE. In addition to the factors that influence on the formation of the BUE, it was also studied the changes in the cutting parameters that it provides during the machining processes. Parameter such as the rake angle, shear force, shear angle, cutting speed, cutting tool wear and poor surface finish, are directly affected by the BUE. However the poor workpiece surface finish and accelerated wear of the cutting tool are undoubtedly the worst damage caused by the appearance of the BUE, since they have a greater influence on the production costs. Therefore, it was also necessary to study the methods used to eliminate or reduces the BUE in machining processes. Methods such as a increasing in the cutting speed, the coating of the cutting tool by thermal treatments and the use of cutting fluids, exert great influence against the BUE formation and the damage caused by it. In this context, it is important to highlight the important role played by the cutting fluid, which even although not avoid the appearance of the BUE, during machining in the presence of this phenomenon, the use of it reduces the adhesion of detached fragments of the BUE on the surface of the piece, and consequently reducing the roughness of it