State of the art in processing of shape memory alloys with electrical discharge machining: A review

Abstract

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.

A comprehensive review on metallic implant biomaterials and their subtractive manufacturing

“…Besides high toughness and strength, some of the significant challenges in the traditional machining of metallic implant biomaterials lie in the extreme sensitivity of these materials such as Mg (due to high flammability), NiTi (due to susceptibility to the temperature-induced transition of phase), and Ti-based alloys (due to high hardness) towards cutting-induced temperature variations, high strain-rate, and consequent phase transformations [ 54 , 135 , 176 ]. In this regard, the advanced manufacturing processes constituting the non-traditional subtractive manufacturing techniques such as laser machining (LM), waterjet machining (WJM), and electric discharge machining (EDM) are the potential alternatives for effective machining of Nitinol [ 177 , 178 ]. The non-traditional subtractive manufacturing techniques subtract unwanted and surplus material by different electrical, chemical, mechanical, thermal, or combinations of these energies without applying the cutting tools used in traditional machining techniques.…”

Fatigue performance of surface ground and wire electrical discharge machined TiNi shape memory alloy

“…Published research on the EDM of SMAs have largely focused on the wire-EDM (WEDM) configuration and have primarily involved investigating the effect of key operating parameters on resulting workpiece surface and subsurface characteristics together with material removal rate (MRR). 14 When evaluating the WEDM of a ternary TiNiCu (titanium-nickel-copper) based SMA, Narendranath et al 15 reported that workpiece surface roughness generally increased with higher peak current (5 A) and pulse on time due to the greater discharge energy and spark intensity, although surface roughness was found to decrease with increasing pulse on time at lower peak current (3 A). Non-linear trends however were observed for MRR due to the interactions between the process parameter levels (peak current, pulse on time and pulse off time) employed, which led to variations in material melting and re-solidification rates in the spark gap as well as flushing efficiency.…”

Parametric investigation of tool wear rate in EDM of Fe-based shape memory alloy: microstructural analysis and optimization using genetic algorithm

“…Under certain conditions, superelasticity (in alloys) or viscoelasticity (in polymers) is also commonly observed. Arne Olander first discovered SMA or “smart alloy” in 1932, and Vernon first described the term “shape memory” for his polymeric dental material in 1941 (Singh et al , 2020). A broad range of SMAs in solid , film and even foam shapes have been developed presently.…”

“…A broad range of SMAs in solid , film and even foam shapes have been developed presently. Among them, there are mainly three alloy systems reported, namely, NiTi-based, copper (Cu)-based (CuZnAl and CuAlNi) and iron (Fe)-based alloys (Singh et al , 2020). The demand for SMAs has been quite increasing in respect of engineering and technical applications in a number of commercial fields such as in consumer goods and industrial applications, structures and composites, automotive, aerospace (Singh et al , 2018), mini actuators, micro-electromechanical systems, robotics, biomedical and even in fashion (Singh et al , 2019a, 2019b).…”