Increasing machinability of grey cast iron using cubic boron nitride tools: Evaluation of wear mechanisms

摘要

This paper presents the analysis and experimental results on the complexity of machining grey cast iron in a high production automotive industry, where surface quality, tolerances and productivity are the most specified customer requirements. The machining of a central housing of turbo charger unit in high speed turning process using polycrystalline cubic boron nitride (CBN) tools coated with titanium nitride (TiN) has been evaluated. The main limitations of machinability are appearing of burr, adhesive wear and flank wear mechanism. The cutting tool geometry and feed rate have been varied while the other parameters, such as cutting speed and depth of cut, are kept fixed. After the flank wear on the tools is monitored, it is concluded that for a certain number of work-pieces machined, the wear process on tools is less severe with using of positive tool rake insert. The machinability is additional increased with improved cutting strategy in the way of burr appearance and with rolling of formatted burr. The worn surfaces are analyzed with an electronic microscope.