Processing of curved profiles on Ni-rich nickel–titanium shape memory alloy by WEDM

ABSTRACT

In wire electrical discharge machining (WEDM) process, to the machine, sharp corner without error is an extremely challenging issue which is vital for precision machining. Owing to the presence of huge wire deflection, the accuracy of the machined corner is undesirably affected. The aim of this study is to explore the effect of process parameters namely, spark on time, spark off time, wire tension, wire feed rate, and spark gap voltage on corner error for acute angle (60°), right angle (90°) and obtuse angle (120°) triangular profiles during WEDM of Ni_50.89Ti_49.11 shape memory alloy (SMA). Owing to the effect of discharge concentration, corner error for acute angle profile is predominantly affected by spark on time, spark off time, and spark gap voltage. Wire tension was the most influencing parameter for corner error of obtuse and right angle profile due to the effect of wire deflection and wire vibration, whereas wire feed rate has trivial effect for all type of profile. In order to reduce the corner error, pulse modification technique was utilized. At low pulse parameters, corner error for 60°, 90°, and 120° profile was reduced by 43.38%, 31.12%, and 29.04%, respectively, as compared to high pulse parameters.

KEYWORDS:

• WEDM
• SMA
• corner error
• wire deflection
• S_ON
• S_OFF
• SV