Developmental and Experimental Study of Rotary Ultrasonic drilling process

The proper selection of machining conditions and machining parameter is an important aspect, before going to machine a brittle material by rotary ultrasonic drilling process Because these conditions will determine such important characteristics as; Material removal rate (MRR) and Surface roughness (SR). The purpose of this work is to determine the optimal values of machining parameters of rotary ultrasonic drilling process. The work has been based on the effect of three design factors: Tool feed rate, vibration frequency and grain size of abrasive particle on such characteristic like material removal rate (MRR). This work has been done by means of the technique of design of experiment (DOE), which provides us to perform the above-mentioned analysis with small number of experiments. In this work, a L9 orthogonal array is used to design the experiment. The adequate selection of machining parameters is very important in manufacturing system, because these parameters determine the surface quality and dimensional accuracy of the manufactured part. The optimal setting of the parameters are determined through experiments planned, conducted and analyzed using the Taguchi method. Keywords: RUSM, Material removal rate, Drilling, Taguchi method

Precise Drilling of Holes in Alumina Ceramic (Al2O3) by Rotary Ultrasonic Drilling and its Parameter Optimization using MOGA-II

Alumina is an advanced ceramic with applications in dental and medical sciences. Since ceramics are hard and brittle, their conventional machining is expensive, arduous, and time-consuming. As rotary ultrasonic machining is among the most adequate and proficient processing techniques for brittle materials like ceramics. Therefore, in this study, rotary ultrasonic drilling (RUD) has been utilized to drill holes on alumina ceramic (Al2O3). This study investigates the effect of key RUD process variables, namely vibration frequency, vibration amplitude, spindle speed, and feed rate on the dimensional accuracy of the drilled holes. A four-variable three-level central composite design (thirty experiments on three sample plates) is utilized to examine the comparative significance of different RUD process variables. The multi-objective genetic algorithm is employed to determine the optimal parametric conditions. The findings revealed that material removal rates depend on feed rate, while the cylindricity of the holes is mostly controlled by the speed and feed rate of the spindles. The optimal parametric combination attained for drilling quality holes is speed = 4000 rpm, feed rate = 1.5 (mm/min), amplitude = 20 (µm), and frequency = 23 (kHz). The validation tests were also conducted to confirm the quality of drilled holes at the optimized process parameters.