Workpiece structure deformation caused by high speed cutting

The hard turning and grinding of High Speed Steel (HSS) materials with hardness of 61 HRC significantly changes structural properties. Estimators of the cutting conditions are surface roughness, dimensions, tolerances and required structure of the surface layer. Vacuum heat treatment of HSS for cold working applications was used as yielded material with greater toughness, while the hardness was maintained constant or even increased. HSS-BRM2 material that was vacuum quenched and tempered was machined. After the machining with that kind of tool property, the surface layer of the workpiece can be completely damage-free. Practical implications assume that a hard turning is a semi finishing or finishing process relevance. Surface roughness is a consequence of both cutting instability and of tool/workpiece loading condition. Originality of this paper is in an analysis of sources and prevention of workpiece material structure damage while reaching high machined surface quality and workpiece geometrical tolerances. [Received on 18 November 2005; Accepted on 12 February 2007]