Powder mixed electrical discharge machining (PM-EDM) is a technological advancement in electrical discharge machining (EDM) processes where fine powder is added to dielectric to improve the machining rate and surface quality. In this paper, machining of Nimonic-90 was carried out using fabricated PM-EDM, setup by adding silicon powder to kerosene oil. The influence of four input process parameters viz. powder concentration (P_C), discharge current (I_P), spark on duration (S_ON), and spark off duration (S_OFF) has been investigated on surface roughness and recast layer thickness. L9 Taguchi orthogonal and grey relational analysis have been employed for experimental design and multi-response optimization, respectively. With the addition of silicon powder to kerosene oil, a significant decrease in surface roughness and recast layer thickness was noticed, as compared to pure kerosene. Spark on duration was the most significant parameter for both surface roughness and the recast layer thickness. The minimum surface roughness (3.107 µm) and the thinnest recast layer (14.926 μm) were obtained at optimum process parameters i.e., P_C = 12 g/L, I_P = 3 A, S_ON = 35 μs, and S_OFF = 49 μs using grey relational analysis.

Shape memory alloys (SMAs) have exceptional properties, namely, shape memory effect, superelasticity and other enriched physical and mechanical properties. The conventional machining of these alloys is associated with several severe difficulties. Electric discharge wire cutting (EDWC), an advanced machining process, is utilized to machine Ni_50.89Ti_49.11 SMA under this investigation. The aim of this investigation was to reveal the effect of EDWC variable parameters such as pulse on time ( T_ON), wire feed (WF) rate, spark gap voltage (SV), wire tension (WT) and pulse off time ( T_OFF) on recast-layer thickness (RLT) and a foreign element atomic content (FEAC) using the one-factor-at-a-time approach. Scanning electron microscope equipped with energy dispersive X-ray spectroscopy facility was utilized to analyse RLT and FEAC. RLT and FEAC are varied linearly and nonlinearly respectively with T_ON, T_OFF and SV. A thick recast layer with a high percentage of FEAC was formed on the machined surface of Ni_50.89Ti_49.11 SMA at a higher T_ON and a lower T_OFF and SV. However, RLT and FEAC are slightly varied with WF and WT.

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.

Surface characteristics are the major challenges faced by the manufacturing industry when materials are machined with electrical discharge machining. Magnetic Field assisted powder mixed electrical discharge machining (MFAPM-EDM) is hybrid machining process which has shown the good potential of improving the surface characteristics. In this present paper, machining of aluminium 6061 alloy was carried out with aluminium powder mixed in EDM oil and in presence of magnetic field using EDM process Magnetic field, spark on duration, spark off duration, pulse current and powder concentration were selected as variable machining parameters and surface roughness as a response. Box-Behnken design approach based on response surface methodology was used for performing the experiments. In the present analysis, current was observed as the most significant parameter followed by spark on duration, powder concentration and magnetic field on surface roughness. Improvement in surface roughness with lesser voids and craters were observed under the influence of magnetic field and aluminium powder mixed in EDM oil.