Furação de ferros fundidos de alta resistência aplicados em cabeçotes de motores

Abstract

In recent years, the need to reduce pollution has driven the growth of technology for engines. The development of diesel engines is determined by the constant effort to reduce weight and improve performance. Thus, it is necessary that components such as engine blocks and cylinder heads, can withstand increased peak pressure in the combustion camera. Therefore, an increased mechanical strength of the materials used in the manufacture of engine blocks and heads is required, enabling these parts withstand higher pressures, thereby reducing the possibility of premature failure of these components. Due to the smaller piece thicknesses obtained, lighter and less polluting engines can be manufactured. However, this fact is a challenge for machining due to lower productivity and higher costs with cutting tools. In this sense, this study aims to evaluate the machinability of high-strength cast irons for use in engine cylinder heads through drilling tests, a process chosen because it is widely used in the manufacture of these items. Basically, the research focus on the study of the machinability of two materials with high resistance, the grey cast iron FC-300 with refining of the graphite and addition of molybdenum and the grey cast iron FC-300 with addition of molybdenum. For comparison purposes other two materials were also studied, the grey cast iron FC-250 and the compact graphite iron CGI-450. A steel drill with interchangeable carbide tips was used in the drilling tests. As machinability parameters were used the drill s life, the thrust force and torque, and the quality of the holes produced. Overall, the results showed that the grey cast iron FC-250 showed the best machinability, followed by the grey irons of the 300 class, while the compacted graphite iron has demonstrated the worst machinability.