Study of micro ball end mill geometry and measurement of cutting edge radius

Cutting edge radius plays an important role in conventional micro machining process, as it is of the same order as uncut chip thickness. Therefore it is important to measure the edge radius accurately. There is no recommended methodology, as of now, to measure edge radius of a ball end mill. An attempt is made in this paper to study edge radius of ball end mill at normal and transverse planes on a virtual ball end mill generated using kinematic relations in CAD environment. In the present study, non-destructive methods using confocal microscope and stereo microscope are used to measure edge radius. These measurements capture the edge radius on the transverse plane. For confirmation, the tool sectioned in the transverse plane by a low speed diamond saw is examined under scanning electron microscope and the radius is assessed using suitable software. Among the non-contact approaches proposed in this work, confocal method appeared to be more reliable considering the reproducibility aspect.