Caracterização da microfuração de Inconel 718 realizada pelos processos de eletroerosão por penetração de furo rápido e pela furação a laser por trepanação

Abstract

Fast hole EDM and trepanning laser drilling are two techniques used in the manufacture of small diameter holes (between 0.18 and 2 mm) in materials with high hardness, high abrasion resistance and an ability to maintain mechanical properties at a high temperature. The small diameter holes are commonly used for aerospace components, and the medical and dental industry, as well as for gas turbine components such as rotors, vanes and blades.The holes in gas turbine components act as cooling mechanism for these components which are subjected to high temperatures.The objective of this study is to characterize the micro-holes obtained through the two manufacturing techniques cited. Through a work process and productivity assessment and inspection of the finish and size of the holes manufactured by Inconel 718, it was possible to characterize each technique cited. Holes were formed of approximately 0.9 mm diameter, by fast hole EDM drilling using two electrode materials: copper and brass; and was carried out by trepanning laser drilling. A central composite (statistical) design was created to determine the influence of the main input parameters. The results showed the influence of parameters on the variation of responses in the following aspects of the assessment: the variation in the removal rates of material, electrode wear rate (for drilling with EDM), dilatation of holes, hole channel roughness, the thickness of the heat-affected zone, splashing, craters and a change in the chemical composition in the region of the machined metal base. Although greater productivity is achieved through trepanning with a laser technique than the EDM it was found that laser drilling causes a higher concentration of cracks and increased the thickness of the HAZ as compared with the holes made by EDM. Thus, there is no single process that meets the requirements of every aspect of the evaluation. Each manufacturing process has its own benefits and drawbacks and these must be taken into account when selecting one of the techniques.