This work focuses on studying the impact of process parameters on the machining performance of rotary ultrasonic drilling of BK-7 glass and improving the machining efficacy by simultaneous optimization of conflicting output responses using utility approach. Taguchi based L9 array has been employed for framing the experimental work and to optimize output characteristics individually. Feed rate, tool rotational speed and ultrasonic power have been elected to understand their impact on material removal rate (MRR) and surface roughness (SR). Analysis of means (ANOM) has been implemented on raw data to identify the % contribution of statistically significant factors. Utility approach has been executed for simultaneous optimization of performance attributes. Middle level of feed along with highest levels of tool rotation speed and ultrasonic power, were predicted as optimal solution for superior performance. Feed was found to have maximum impact on MRR and SR followed by tool rotation speed and ultrasonic power. All the predicted results agreed well with experimental results at 95% confidence level. SEM micrographs of machined surfaces showed the presence of plastically deformed regions at lower levels of feed; whereas higher feed led to dominance of brittle fracture. Further, SEM micrographs revealed the occurrence of grain pullout, grain fracture and bond fracture of lateral as well as end face of the tool.
Kumar, V., & Singh, H. (2019). Optimization of rotary ultrasonic drilling of optical glass using Taguchi method and utility approach. Engineering Science and Technology, an International Journal, 22(3), 956–965. https://doi.org/10.1016/j.jestch.2019.02.004