Size Effects on Surface Generation in Micro Milling of Hardened Tool Steel

This paper presents the results of an extensive experimental investigation concerning size effects on surface generation by ball nose and flat end micro milling hardened tool steel. Cutting parameters were selected on the basis of a modular description of the uncut chip geometry. A theoretical model of the generated surfaces was used as a reference and compared with measurement results and visual inspection using an SEM. Two main effects have been observed on the tool-work material interaction at micro scale. These are responsible for the limited reduction of the roughness amplitude parameters with tool diameter and occur when the cutting edge radius to uncut chip thickness ratio becomes critical.