Laser-assisted machining of compacted graphite iron

Compacted graphite iron (CGI) is a material currently under study for the new generation of engines, including blocks, cylinder liners, and cylinder heads. Its unique graphite structure yields desirable high strength, but makes it difficult to machine, thus resulting in a machining cost. Laser-assisted machining (LAM) is adopted to improve its machinability and hence machining economics. The machinability of CGI is studied by varying depth of cut, feed, and material removal temperature and then evaluating resultant cutting forces, specific cutting energy, surface roughness, and tool wear. At a material removal temperature of 400 °C and a feed of 0.150 mm/rev at a cutting speed of 1.7 m/s, it is shown that tool life is 60% greater than conventional conditions at a feed of 0.100 mm/rev. Surface roughness is improved 5% as compared to conventional machining at a feed of 0.150 mm/rev. CGI microstructure evaluated post machining by sectioning and polishing shows no change. An economic analysis shows that LAM can offer an approximately 20% cost savings for the machining of an engine cylinder liner.