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Powder mixed EDM is getting popularity due to its improved machining efficiency. The properties of powder particles play an important role in influencing the process. Therefore, the present work is focused on the phenomenon of electrical discharge machining (EDM) process for different dielectric conditions. Experiments on EDM have been performed using plain deionized (DI) water, nonconductive Al2O3 powder mixed DI water, and conductive Al powder mixed DI water as the dielectric. The experimental result shows that the conductive powder mixed EDM process is more stable and is able to generate better surface topography compared to other processes. To explicate the observation, sparking behavior, bubble formation, and interelectrode gap (IEG) for the different dielectric conditions have been investigated using high-speed camera. The average interelectrode gap was measured as 0.05 mm, 0.1015 mm, and 0.1392 mm in conventional EDM, nonconductive alumina powder mixed EDM, and conductive aluminum powder mixed EDM process, respectively. Similarly, mean sizes of bubble diameter in conventional EDM, alumina powder mixed EDM, and aluminum powder mixed EDM are observed as 0.1583 mm, 0.17789 mm, and 0.20621 mm, respectively. [ABSTRACT FROM AUTHOR]

In this paper, an attempt is made to explore the possibilities of modifying the dielectric by adding alumina (Al2O3) nanopowder for improving the machining performances. The performance of newly developed nano powder-mixed electrical discharge machining (NPMEDM) process is compared with conventional EDM. Peak current, gap voltage and pulse-on time are taken as considerable process parameters to investigate material removal rate (MRR), surface roughness (SR), recast layer thickness, surface morphology, surface topography and induced residual stress. It is observed that the nanopowder-mixed dielectric medium gives better surface finish and higher metal removal rate as compared to conventional dielectric. The value of MRR increases from 32.75 to 47 mg/min and surface roughness improves from 2.245 to 1.487 μm. Thereafter, atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM) investigation of the machined surface reveals that presence of micro-crack, micro-hole and uneven deposition decrease substantially during NPMEDM process. Also, induced tensile residual stress on the machined surface significantly reduces in this modified process. Further, the basic mechanism of these processes are investigated by analysing pulse train discharge waveforms and reveals the better sparking stability of NPMEDM process, which results in the higher MRR and better surface quality. [ABSTRACT FROM AUTHOR]

The work presents the surface integrity of TiN/TiAlN coated surfaces produced using hexagonal boron nitride suspension in the dielectric fluid through the micro-electrical discharge coating (μ-EDC) process. The performance of the coated surfaces is evaluated on the grounds of surface topography, wettability, indentation depth, layer height, crack density, roughness profiles, residual stress, and composition analysis. The recast layer height varies between 1.53 μm and 13.38 μm, while the water contact angle lies in the range of 91.28° to 118.23° (hydrophobicity is induced). The residual stress generated due to the presence of micro-cracks on the coated surfaces prepared at a maximum voltage (60 V) and powder concentration (12 g/L) varies between 225.87 MPa and 300.93 MPa. The occurrence of Ti, Al, Cu, Zn, V, B, N, and O in EDX plots affirmed the transfer of tool and dielectric material to the work surface. The indentation depths obtained in the study lies within the range of coating thickness. The surface roughness parameters, i.e., R a , R q , R z , R sk , and R ku are also evaluated in this work. Such micro-deposited surfaces find application in lab-on-chip devices where selective surface modification is needed. • Modified layer of TiAlN/TiN formed on Ti-alloy using hBN powder mixed dielectric micro-electrical discharge coating. • Surface integrity and residual stress analysis conducted on the coated samples. • Increase in residual stress observed with increasing duty factor. • Water contact angle varies from 91.28° to 118.23° for the coated samples. • Metallurgical transformations account for hard and lubricating coatings. [ABSTRACT FROM AUTHOR]

The study acclaims the generation of hard, wear-resistant, and lubricating layer on Ti alloy using molybdenum disulfide (MoS2) powders mixed in dielectric (deionized water) using a brass tool electrode (diameter 800 μm) through the micro-electrical discharge process. The deposition rate, micro-hardness, recast layer, and surface roughness were studied for the surface generated through the process and correlated with the XRD, AFM, electron probe micro-analyzer, EDS analysis, and FESEM images. Results indicate that a higher voltage (60 V) and powder concentration (12 g/L) increase the material deposition rate in the form of intermetallic compounds deposited on the recast layer. The coated layer formed shows an increase in micro-hardness ranging from 426.42 to 714.25 HV, which is more when compared to the base material hardness of 417.61 HV. In addition to this, lower micro-cracks were seen at high powder concentration, voltage, and duty factor with improved surface quality. The pin-on-disc wear test of the coated samples was performed, and results indicated that the specific wear rate decreased with the increase in duty factor due to the formation of hard and wear-resistant intermetallic compounds as confirmed from the EDS and XRD plots. [ABSTRACT FROM AUTHOR]