Investigation of critical edge radius effect for the variation of ultra-precision machining results of difficult-to-cut materials

摘要

The effects of properties of difficult-to-cut materials on the behaviour of critical cutting tool edge radius for the variations of machining results have been investigated. In ultra-precision machining, when undeformed chip thickness (a) becomes smaller than cutting tool edge radius(r), the governing parameter identified as relative tool sharpness, RTS (a/r). At smaller RTS, with highly negative effective rake angle, the intense compressive stress of the rounded cutting edge transforms material removal phenomena from shearing to "extrusion-like" deformation mechanism. The variations of machining forces, surface finishing, material flow stress, microchip morphology and surface microstructure quantifies the effective machining performance of the difficult-to-cut materials like Ti6Al4V alloy and Inconel 625. The results of this study will enhance the current knowledge of precision to ultra-precision machining industries to support the emerging fields of aerospace, electro-mechanical, oil field and biomedical applications.