Murali M. Sundaram

Micro Ultrasonic Machining Using Oil Based Abrasive Slurry

Advanced engineering materials posses excellent properties such as high wear resistance, and inertness to corrosion and chemical reactions. Since these materials are usually hard, brittle, chemically inert, and electrically nonconductive, they pose serious machinability challenges. Micro ultrasonic machining (Micro USM) is an emerging method for the micromachining of hard and brittle materials without any thermal damage. This paper presents the results of micro ultrasonic machining using oil based abrasive slurry. Details of the in-house built experimental setup used to conduct the experiments are explained. The influence of process parameters such as slurry medium, slurry concentration, and abrasive particle size on the performance of micro USM are reported. It was noticed that the evidence of three body material removal mechanism is predominant for micro USM using oil based slurry. In general, the material removal rate increases with the increase in the abrasive particle size for both aqueous abrasive slurry and oil based abrasive slurry. Further, material removal rate is consistently higher for experiments conducted with aqueous abrasive slurry medium. On the other hand, it is noticed that the oil based slurry medium provides better surface finish. It is also noticed that the smaller abrasive grains provide better surface finish for both aqueous, and oil based abrasive slurry mediums. Role of slurry concentration is ambiguous, as no clear trend of its effect of on process performance is evident in the available experimental results.Copyright

Generation of High Aspect Ratio Micro Holes by a Hybrid Micromachining Process

Drilling a micro hole with an aspect ratio above 10 is a challenging task for any-micromachining process. In micro electro discharge machining (micro EDM), a proven metallic micromachining process, this is due to the problems associated with debris removal. In such cases, where the capabilities of existing macro machining methods are constantly being challenged, innovative micro manufacturing approaches are required to make progress. Hybrid micromachining is one such approach in which the synergy of constituent processes is exploited to achieve desired results. In this paper, the results of ultrasonic vibration assisted micro electro discharge machining process are presented. This hybrid process is capable of deep hole drilling with aspect ratio of 20 in austenitic stainless steel by overcoming the limitations in the debris removal faced in the typical micro EDM process. Other benefits of ultrasonic vibration are the savings in machining time, and less tool wear. It is also noticed that the ultrasonic vibration causes some shape distortion and produces rougher machined surface.Copyright