Estudo da usinabilidade dos ferros fundidos cinzentos ligados (CrCuSn e CrCuSnMo) e vermicular classe 350 no fresamento frontal em alta velocidade de corte

Abstract

Cast iron is used to manufacture engine blocks due to its mechanical and physical properties like thermal conductivity and dumpy capacity, which are fundamental to these applications. Compacted graphite iron (CGI) has higher mechanical strength compared to gray cast iron and can be a great advantage in these type of mechanical parts. The compression rate can be increased in the engine resulting in a higher efficiency for example. Alloying elements are also used to increase the mechanical resistance of the gray cast iron, resulting in a material with similar mechanical properties to the CGI. The mechanical and physical properties can be similar for both materials, however the CGI has a poor machinability compared to gray cast iron, even for the alloyed material. These means it is important to investigate the behaviour of the CGI for the main cutting process. The main objective of this work is the investigation of the machinability of two types of alloyed gray cast iron (CrCuSn and CrCuSnMo) and the compacted graphite iron class ASTM 350. Tool life tests were carried out in a milling operation and the flank wear was the parameter used to define the end of the tool life. Investigations using observations into the scanning electron microscope SEM were also used to analyse the wear mechanisms. It was used cemented carbide inserts coated with Al2O3 over a layer of TiCN. All the tests were carried under dry conditions. Feed per tooth and depth of cut were constant, 0,2mm/rev and 1mm respectively. It was used three values of cutting speed, 600, 800 and 1000m/min. The results shown that the gray cast iron alloyed with CrCuSnMo is the most difficult to machine material at the higher cutting speeds. At the cutting speed of 600m/min the CGI is the most difficult to cut material.