Machinability study of biolox forte ceramic by milling microchannels using rotary ultrasonic machining

Rotary ultrasonic machining (RUM) shows capabilities in several manufacturing applications specifically for fabrication of high-quality features on ceramic materials. However, surface fracturing and edge chipping are the persistent issues during the RUM of ceramic materials. This research reports an experimental investigation to analyze the machinability of the biolox forte ceramic by milling microchannels using RUM. Machinability is studied by analyzing the performance measures such as the surface roughness, surface morphology, edge chipping and tool wear. The effects of the five major RUM input parameters including spindle speed, feed rate, depth of cut, vibration amplitude, and vibration frequency are taken into consideration on the machinability of the biolox forte material. An attempt has been made to characterize the material removal behaviour within the microchannels. The results reveal more brittle fracturing and deep pits on the channel bed as compared to the channel sidewall due to the difference in the cutting action of the RUM tool. Furthermore, it is observed that the channel sidewalls always show a coarse machined region near the top edge and a relatively smooth machined region up to the channel bed. The energy dispersive spectroscopy (EDS) analysis reveals that no change in the composition of the biolox forte occurs and no traces of tool material are observed in the microchannels. The scanning electron microscopy (SEM) analysis of the tool shows that the plastics deformation, attritious wear, and the tool edge rounding and chipping are the primary tool wear mechanisms. By selecting the appropriate RUM parameters, microchannels with good surface finish (Ra = 0.21 mu m), smoothed morphology and minimal edge chipping (16.3 mu m) can be milled on the biolox forte material.