Study of surface crack density and microhardness of Aluminium 6061 alloy machined by EDM with mixed powder and assisted magnetic field

Magnetic field assisted powder mixed electrical discharge machining (MFAPM-EDM) has emerged as hybrid electrical discharge machining (EDM) technique which improves machining performance by the addition of powder in dielectric and under the influence of magnetic field. In the present article, Aluminium 6061 alloy was machined through fabricated MFAPM-EDM set-up considering the one-parameter-at-a-time method. The individual effect of process parameters, namely pulse on duration (PON), pulse off duration (POFF), discharge current (IP), magnetic field strength (MF) and powder concentration (PC) on surface crack density (SCD) and micro hardness (MH) has been studied. Pulse on duration was observed as the most dominating process parameter accompanied by peak current, powder concentration and magnetic field for both SCD and MH. Lower SCD (0. 0063 µm/µm 2 ) and higher MH (188. 21 HV) on machined surface were observed at PON= 90 µsec, POFF=45 µsec, IP=13 A, PC =10 g/l and MF= 0. 3 T. Machining of AA6061 with MFAPM-EDM process revealed 85% and 76% improvement in SCD and MH, respectively. XRD analysis witness an increase in MH due to the presence of oxide as well as carbide layer on machined surface.

Wire Electric Discharge Machining Induced Surface Integrity for Ni55.95Ti44.05 Shape Memory Alloy

The current study unveils the variation of surface integrity aspects (micro-hardness, surface crack density, and surface characteristics) for Ni55.95Ti44.05 shape memory alloy (SMA) with wire electric discharge machining (WEDM) process parameters, namely, pulse off time, wire tension, spark gap voltage, wire feed rate and pulse on time. The experimental results reveal that micro-hardness displays direct relationship with spark gap voltage, pulse on time, and pulse off time whereas surface crack density shows direct relationship with pulse on time and inverse trend with spark gap voltage and pulse off time. Wire tension and wire feed rate show trivial effect on both surface crack density and micro-hardness. Machined surface comprises crater, micro-cracks, micro-voids, pockmarks, and lumps of debris while inspecting through a scanning electron microscope (SEM). During energy-dispersive X-ray spectroscopy (EDS) analysis, the foreign elements namely carbon, oxygen, copper and zinc were also detected on the surface. The high energy density at higher pulse on time adversely affects the surface morphology. The formation of large size craters (deep and wide) with more cracks on the machined surface were observed at lower pulse off time as compared to higher pulse off time.

Effect of process parameters on the surface crack density of AISI 304 in PMEDM

Purpose In this study, powder mixed electro discharge machining (PMEDM) has been performed for the machining of AISI 304 stainless steel by using the tungsten carbide electrode when silicon carbide (SiC) powder is mixed with kerosene. The purpose of this study is to find the optimal value and ascertain the effect of significant machining parameters on surface crack density (SCD) of a machined surface of AISI 304. Design/methodology/approach A face-centered central composite design-based response surface methodology has been adopted for designing this experiment. Findings An increase in peak current and powder concentration decreases SCD, which is the main goal of this investigation. Originality/value From this investigation, an optimal value has been achieved to minimize the SCD and prevent fatigue and corrosion resistance of the workpiece.

A Study on White Layer Thickness and Surface Crack Density in Rotary EDM of RENE80 Nickel Superalloy

In this paper, rotary electrical discharge machining of RENE 80 nickel super alloy is carried out to study the effect of process parameters like peak current, pulse on time, pulse off time and rotational speed of electrode on surface integrity characteristics like white layer thickness and surface crack density. The number of experiments, optimum levels of the parameters and their effects are studied using Taguchi method. The significant process parameters are identified using analysis of variance. It is found that the responses are affected mainly by peak current and pulse on time. The experimental results reveal that white layer thickness increases with increase of peak current and pulse on time whereas the surface crack density decreases with increase of peak current and pulse on time.