Defect Modelling and Tool Selection for Ultrasonic Machining Process Using Finite Element Analysis.

The machining performance of an ultrasonic machine mainly depends on the ability of the design of ultrasonic tool. A tool is a significant component in the ultrasonic machining process that contacts the abrasive particles to remove the material from the workpiece. The present investigation has considered the design of three different tool profiles as cylindrical, conical and stepped. A defect is introduced in three different orientations namely longitudinal, perpendicular and inclined about the vibration axis in all the respective tool profiles. The effect of vibration frequency during the machining on the defective and non-defective tools is analysed using numerical simulation technique. The study also presents the modal analysis to obtain the mode shapes and natural frequencies of the tool profiles with and without the defect. The induced stress is computed by performing the harmonic analysis for the defective and non-defective tools. Out of the three profiles analysed in this investigation, the conical tool profile without defect results in a maximum stress of 133 MPa and the same in presence of the internal defect in the inclined orientation is 537 MPa, which is 35% higher than the ultimate tensile strength of the tool material. The comparison of the tool profiles demonstrates that the stepped tool results in maximum Eigen frequency of 134.24 kHz with maximum stress of 453 MPa with the defect in the inclined axis at 30 kHz excitation frequency. [ABSTRACT FROM AUTHOR]