Improvement of surface flatness in face milling based on 3-D holographic laser metrology

This paper presents two approaches to improve the flatness of face milled surface based on 3-D holographic laser measurement. The first approach, cutting depth compensation method, generates a compensation cutting profile that is ideally a mirror image of the surface profile from a straight cutting path. The surface profile describes the machined surface along the feed direction and is extracted using surface decomposition technique developed in this study. Issues of back-cutting and gouging, which limit the applicability of this approach, are also addressed. The second prescribed approach is the feed rate optimization method. In this technique, the tool feed rate is altered to match the axial force on the cutter with the local compliance of the workpiece. This is performed with the aim of reducing force-induced distortion. Experiments using aluminum workpieces and 50.8 mm diameter face mill demonstrate that the surface flatness can be reduced from 32 to 7 μm with the cutting depth compensation method. With the optimized feed rate, the flatness can be reduced by 19 μm with the same cycle time as that of the original constant feed rate.