Machinability study of Zr-Cu-Ti metallic glass by micro hole drilling using micro-USM

Metallic glasses are the new class of materials researched and developed extensively for their applications in fabrication of micro components because of their exceptional mechanical properties. Micro machining of metallic glass to the required tolerance without any structural damage is a challenging task. Micro-ultrasonic machining (micro-USM) is a nontraditional machining process which can machine micro features in hard and brittle materials without heat generation. In present research work the machinability of Zr60Cu30Ti10 metallic glass is investigated by micro hole drilling using micro-USM. Machinability study is carried out by analyzing the performance measures like overcut, edge deviation, taper angle, material removal rate (MRR) and tool wear rate (TWR) with respect to the input machining parameters such as feed, abrasive grit size and concentration of abrasive slurry. The edges of the drilled holes are analyzed using scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) to study the micro structural changes which are taken place in metallic glass due to micro machining. SEM and EDS analysis revealed that the amorphous structure of metallic glass is not affected during machining by micro-USM. A range of feed rate, abrasive grit size and slurry concentration are recognized for micro-USM drilling in metallic glass using multi-objective optimization on the basis of ratio analysis (MOORA) method. The micro-USM drilling in metallic glass provides a new horizon for the precision machining of glassy alloys otherwise which are very difficult to machine conventionally without any change in its amorphous structure.