Surface integrity of NiTi-SMA during WEDM: effect of spark parameters

Abstract

ABSTRACT The current study looks at surface integrity measures for example surface crack density, surface roughness, recast layer thickness, and foreign elements content in wire electric discharge machining (WEDM) of the Ni55.95Ti44.05 shape memory alloy (SMA) with purposefully varied spark parameters (spark frequency, spark energy density, and spark gap voltage). Surface roughness has a similar tend to surface crack density, which increases with an increase in spark energy density and decreases with an increase in spark gap voltage and spark frequency. As the spark energy density declines and the spark gap voltage and spark frequency rise, foreign elements content and recast layer thickness decrease. Scanning electron microscope (SEM) and optical profilometer observations of the surface topography of SMA following WEDM show the presence of lumps, voids, pockmarks, discharge craters, microcracks, and a layer of melted material that has resolidified. Energy dispersive spectroscopy (EDS) studies show that foreign elements are deposited on machined surfaces from wire electrode and dielectric fluid.