Single abrasive particle impingements as a benchmark to determine material removal modes in micro ultrasonic machining

The modes under which the material is removed, whether it is brittle or ductile, can be controlled in micro ultrasonic machining through setting of machining conditions and process parameters at desired levels to improve the process productivity as well as surface quality. However, the micro ultrasonic machining process lacks in fundamental understanding of brittle and ductile modes of material removal which is the key to develop predictive process models. In this paper the approach of single abrasive particle impingement is presented for the first time in micro ultrasonic machining with the purpose of providing insights into material removal modes. The morphology of the craters formed by single particle impact at various vibration amplitudes and with different particle sizes is studied using confocal imaging profiler, field emission scanning electron microscopy and atomic force microscopy. The significance of this method lies in catering a benchmark for determining brittle and ductile removal conditions under various process parameters. Also, the outcome of this study can be used to validate the predictive model for brittle and ductile material removal modes, which takes into account kinetic energy of the impinging particle as well as threshold kinetic energy of the material and is crucial for estimation of material removal rate in micro ultrasonic machining.

► We presented a method to determine the material removal modes in micro USM.
► We studied the morphology of craters formed by particle impact in micro USM.
► Conditions for ductile and brittle removal modes in Si material were studied.
► Impacting by 0.37 μm particles at 3 μm amplitude caused a purely ductile removal.
► Particle size and vibration amplitude of 3 μm caused a partially ductile removal.