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Shape memory alloys (SMAs) have been well known for their superior and excellent properties which makes them an eligible candidate of paramount importance in real-life industrial applications such as; orthopedic implants, actuators, micro tools, stents, coupling and sealing elements, aerospace components, defense instruments, manufacturing elements, bio-medical appliances, etc. In spite of their exceptional properties, the effective processing of these alloys is always seen as a challenge by researchers around the globe. The present article has been therefore attempted to explore the numerous studies conducted to process these alloys by employing the principles of electrical discharge machining (EDM) and its allied approaches. The NiTi-based SMAs have been revealed to be explored majorly among the several types SMAs. The several investigations carried out in the domain of EDM, Wire-EDM, and some conventional processing of various types of SMAs have also been critically reviewed and reported. It also highlights the numerous experimental, theoretical, modeling, and optimization-based researches attempted in EDM of SMAs. It was also reported that the proper selection of process variables, tool electrode, and the dielectrics can substantially improve the overall process effectiveness. Among the various accessible EDM variants used for the processing of SMAs, attempted by the umpteen investigators, the wire-cut EDM process has been revealed as the most explored one for cutting SMAs than the other allied processes such as: die-sinking EDM and powder-mixed EDM. The micro-machining applications of EDM have also been deliberated briefly. The last section of the article reports about the opportunities and the challenges for future research.

Macor ceramic has been well recognized as an eminent engineering material which possesses enlarged industrial usage owing to its excellent and versatile properties. However, its fruitful and economic processing is still unanswered. This article has targeted to experimentally investigate the influence of numerous process variables on machining characteristics in rotary ultrasonic machining of Macor ceramic. The impact of different input factors, namely, spindle speed, feed rate, coolant pressure, and ultrasonic power has been appraised on process responses of interest, that is, material removal rate and chipping size. The experimental plan was designed by employing response surface methodology through central composite rotatable design. The variance analysis test has also been performed with a view to observe the significance of considered parameters. Microstructure of machined samples has also been evaluated and analyzed using scanning electron microscope. This analysis has revealed and confirmed the presence of dominated brittle fracture that caused removal of material along with the thin plastic deformation in rotary ultrasonic machining of Macor ceramic. The reliability and competence of the developed mathematical model have been established with test results. The multiresponse optimization of machining responses has also been done by utilizing desirability approach, and at optimized parametric setting, the obtained experimental values for material removal rate and chipping size are 0.4762 mm 3 /s and 0.3718 mm, respectively, with the combined desirability index value of 0.937.

Quartz ceramic has been well observed as one of the highly demanded advanced ceramics which is receiving enlarging industrial approbation owing to its excellent and superior properties. However, its fruitful processing with traditional and non-traditional machining methods is still a challenge. The current article has aimed to experimentally investigate the influence of several process variables, namely, spindle speed, feed rate, coolant pressure, and ultrasonic power on machining characteristics of interest, i.e. chipping size, and material removal rate in rotary ultrasonic machining of quartz ceramic. Response surface methodology has been employed to design the experiments and the variance analysis test has also been performed with a view to observe the significance of considered parameters. Microstructure of machined samples has also been evaluated and analyzed using scanning electron microscope. This analysis has revealed and confirmed the presence of dominating brittle fracture that caused removal of material along with the slighter plastic deformation in rotary ultrasonic machining of quartz ceramic. The soundness and competence of the developed mathematical model have been established with test results. The multi-response optimization of machining responses has also been done by utilizing desirability approach, and at optimized parametric setting, the obtained experimental values for material removal rate and chipping size are, 0.6437 mm 3 /s and 1.3326 mm, respectively, with the combined desirability index value of 0.949.