Wire electrical discharge machining of AZ91 magnesium alloy; investigation of effect of process input parameters on performance characteristics

Abstract

Magnesium alloys have wide application in aerospace and automotive industries due to their high strength to weight ratio and desired mechanical properties. In this present research, the effects of three input parameters of the wire electrical discharge machining (WEDM) process, including pulse on time, pulse current, and servo feed rate were studied on the performance characteristics namely; material removal rate, kerf width, and surface roughness during machining of AZ91 magnesium alloy. This research is the first comprehensive study of the electrical discharge machining of magnesium alloys and aims to analyses the machinability and behavior of materials with low melting point and high thermal conductivity during WEDM. For this purpose, 15 experiments were designed by the design of experiments technique. Using response surface methodology, mathematical models were developed and the contribution percentage of each variable input parameter on output parameters was found. Analysis of variance results revealed that pulse on time and pulse current have the most effect on process output parameters, respectively, while the effect of the servo feed rate was insignificant. The experimental results showed that the material removal rate and the kerf width during the WEDM of magnesium is considerably higher than hard materials and it can be reached to about 180 mm 3 min −1 while kerf width and surface roughness are about 0.450 and 4.683 μm, respectively. Despite the high cutting rate, the surface roughness is appropriate and comparable to hard materials, indicating high machinability of magnesium alloys by WEDM. To study the surface topography and microstructural changes, atomic force microscope, scanning electron microscope and EDX analysis have been used. SEM micrographs show that the number of microcracks, indicating the surface damage, is low in the machined surface which shows WEDM capability in producing nondamaged work surfaces. The maximum recast layer thickness is about 6.91 μm and minimum is 3.09 μm.

Analysis of electrical discharge machining parameters for H13 steel using OVAT technique

“…The effect of pulse-on-time on EDMed H13 steel is disclosed in figures 8-10 at a discharge current 9 A and spark gap voltage 50 V, keeping other parameters as constant. Figure 8 illustrates that the material removal rate amplified with an increase in T on due to more pulse energy generated in the working area [28]. It is observed that MRR decreases at a higher value of T on (above 250 μs).…”

The effects of different types and ratios of reinforcement, and machining processes on the machinability of Al2024 alloy nanocomposites

“…This happens due to the melting of the electrode and the machining material during machining, leading to the accumulation of Zn elements from the electrode on the material surface. 42 Figures 17(a) and (b) illustrate the elemental analysis (EDS) of an Al2024 metal matrix nanocomposite with 2% SiC added. As seen in the figures, in addition to the primary metal components, Si, Cu, and Zn elements are also present.…”

Analysis of control factors and surface integrity during wire-EDM of Inconel 718 alloy using T-GRA approach

“…Simultaneously, several studies can be reported in literature that discusses the challenges correlated with precision machining of different materials with wire-EDM [17]. The findings of magnesium alloy in view of efficient machining operation with different facets of the performance and reliability of the magnesium alloy are discussed using wire-EDM [18], [19]. The findings of an experimental study on the selection of processing conditions that decide performance of wire-EDM using aluminium alloy and the optimization abilities of some output responses in wire-EDM of reinforced ZC63 metal matrix composite are discussed [20], [21].…”

“…The quality of finished surface depends on variety of the mechanical and physical characteristics of the test surface particularly, resistance to corrosion, friction, fatigue stability, and loading competency [19], [31]. Thus, the quality of surface obtained throughout the machining of test piece is interpreted by the average roughness height (Ra) and termed as surface roughness (SR).…”