Electrical discharge machining characteristics of nickel–titanium shape memory alloy based on full factorial design

Abstract

Among many shape memory alloys, nickel-titanium (NiTi) alloys are popular due to their superior properties in shape memory effect and superelasticity. They are presently often used in microengineering and medical technology especially in orthopedic and orthodontic implants due to their specific properties. In this study, the electric discharge machine characteristics of NiTi shape memory alloys have been fully investigated by full factorial design. Analysis of mean showed that the material removal rate of NiTi in the electric discharge machine process significantly related to the electrodischarge energy, involving the pulse current and pulse duration. Many electrodischarge craters and recast layers were observed on the electric discharge machine surface of NiTi samples. In addition, there was no significant difference between copper (Cu) and tungsten-copper (W-Cu) electrodes in material removal rate but work stability of W-Cu electrode was longer. On the contrary, quantity of impurity on the surface of the Cu electrode was lower. The specimen's hardness near the outer surface could reach 1200 Hv, which originated from the hardening effect of the recast layer. Here, the microstructure, composition, and hardness of electric discharge machine surfaces are also discussed.

Evaluation of wire electro discharge machining characteristics of Ti50Ni50−xCux shape memory alloys

“…The formation of the alloy compounds observed from the XRD analysis, which in turn causes higher surface hardness. These findings also support the investigations carried out by Alidoosti et al 16 From Fig. 8(b), it is observed that for a fixed pulse on time of 120 ls, pulse off time of 62 ls, and for varying SV the CuZn peak intensity reduced to very low and some peaks are disappeared.…”

“…The layer may exhibit hard brittle nature, stresses caused to produce cracks. 16 C. XRD analysis of SMA after WEDM process Fig. 8(a), for a fixed higher pulse off time and SV, the TiNiCu peak intensity is decreasing with increase in pulse on time.…”

Structural analysis of HyFlex EDM instruments

“…It was also interesting to note that EDM instruments did not exhibit surface pollution from the EDM electrode materials (e.g. Cu or Cu-W alloys), a defect reported for ED-machined NiTi wires (Alidoosti et al 2013). This observation proved the high quality of the manufacturing process of these instruments.…”

“…Cu or Cu‐W alloys), a defect reported for ED‐machined NiTi wires (Alidoosti et al . ). This observation proved the high quality of the manufacturing process of these instruments.…”

Design and Industrial Manufacturing of SMA Components

“…The drawbacks of laser cutting can be overcome by electro discharge machining (EDM), which allows similar tolerances but avoiding HAZ because the melting is promptly followed by an almost instantaneous vaporization of the material. 31 Some contaminants are, however, present on the cuts surface because of the used dielectric medium and the Cu electrode. The EDM limits are mainly because of the low productivity and the width of the cut that is directly related to the electrode diameter: 0.1e0.3 mm.…”