Research on coated wiper insert for milling of compacted graphite iron

Compacted graphite iron (CGI) is increasingly used in industrial production due to its excellent mechanical property, especially in the field of high-performance automotive engine manufacturing, and has become a substitute for gray cast iron (GCI). However, the hard-to-machine problem caused by its excellent physical properties was the main issue affecting the surface quality of the CGI workpiece. As a new type of tool, the wiper insert could effectively improve the surface quality. In order to develop a long lifespan and high-stability wiper insert tool for CGI milling, this study conducted a series of experiments, including tool design and simulation, coating preparation and testing, and tool cutting performance testing. In the optimization of simulation analysis of tool geometric parameters, it was found that the numerical value of curved cutting-edge radius had a more significant impact on the cutting performance of wiper insert. In the coating test, AlCrN-coated wiper insert C with a coating thickness of 2.84 µm had the best load bearing and fracture toughness performance in the coating mechanic test and had the best coating bonding performance in the scratch test. In the milling experiment with a cutting speed of 125.7 mm/min, a feed rate of 0.15 mm/r, and a cutting depth of 0.5 mm, the coated wiper insert C had the longest tool life and the best machined surface quality of the workpiece. Compared to other coated tools, the tool life was extended by at least 15.7%, and the effective cutting area was increased by 20%, which means it was the most suitable tool for machining CGI.