Ultrasonic Machining of Tungsten Carbide Stellite and Diamond

Abstract

This thesis presents an experimental and theoretical analysis of ultrasonic machining (USM) process with respect to machining characteristics and material properties of the work piece. Experimental work has been conducted on tungsten carbide, stellite and poly-crystalline diamond. Titanium alloys (TITAN 12, TITAN 15 and TITAN 31) have been used as the tool materials and aluminium oxide, silicon carbide and boron carbide as the abrasive slurries. The machine used for the experiments was ultrasonic drilling machine (SONIC-MILL, Albuquerque, USA). The data compiled during the experimentation has been used to get the responses in respect of material removal rate (MRR), surface roughness (SR) and tool wear rate (TWR). Further, the results have been modeled for their application in manufacturing industry. In this investigation, the mathematical models considering the material properties have been employed to study the effects of operating parameters such as: power rating, abrasive slurry concentration, grit size of abrasive particles, type of abrasive slurry, tool material and work material .The model formulated in this work has been found to be much simpler in comparison to FEM and the results show an improved correlation with the experimental data. Moreover, the models developed have been capable of predicting the measure of performance for the USM process. For USM processes, graphical representation of MRR, TWR and SR with operating parameters has been shown and compared with available existing results related to ultrasonic machining of titanium alloys. The application of taguchi method and F-test effect for the optimization of the process has been incorporated which was less explored by the previous researchers. By accounting for these phenomena, improved theoretical results have been obtained and consequently better correlation with experimental data is observed. From the experimental observations and with the help of basic power model, the multi-variant co-relation has been established for material removal rate, surface roughness and tool wear rate by varying the power rating, abrasive slurry concentration, grit size of abrasive particles, type of abrasive slurry, tool material and work material. The analysis of results and mathematical model has been developed with the help of statistica 7.0 software. Data related to MRR, TWR and SR for different experimental conditions has been presented. The significance of the responses also has been shown by graphical models. The degree of correlation between the analytical and experimental results is found to be quite satisfactory. Besides the study of surface roughness by stylus method, the machined samples have been studied by scanning electron microscopy (SEM).The photomicrographs demonstrate a typical nature of machined surface, which is hardly evident from conventional stylus measurements, or transverse sections of the machined surface. These studies confirm the conclusions of the previous investigators regarding surface topography and material removal mechanism.