Preetkanwal Singh Bains

Fabrication and Machining of Metal Matrix Composites: A Review

Intrinsically smart, metal matrix composites (MMCs) are lightweight and high-performance materials having ever expanding industrial applications. The structural and the functional properties of these materials can be altered as per the industrial demands. The process technologies indulged in fabrication and machining of these materials attract the researchers and industrial community. Hybrid electric discharge machining is a promising and the most reliable nonconventional machining process for MMCs. It exhibits higher competence for machining complex shapes with greater accuracy. This paper presents an up-to-date review of progress and benefits of different routes for fabrication and machining of composites. It reports certain practical analysis and research findings including various issues on fabrication and machining of MMCs. It is concluded that polycrystalline tools and diamond-coated tools are best suitable for various conventional machining operations. High speed, small depth of cut and low feed rate are a key to better finish. In addition, hybrid electrical discharge machining has proved to be an active research area in critical as well as nonconventional machining since last few years. This paper incorporates year-wise research work done in fabrication, conventional machining, nonconventional machining, and hybrid machining of MMCs. Conclusions and future scope are addressed in the last section of the paper.

Study of Magnetic Field Assisted ED Machining of Metal Matrix Composites

The present study deals with an investigation of the hybrid electric discharge (ED) machining process executed in a magnetic field for improving process performance. Previous magnetic field-assisted electric discharge machining (MFAEDM) techniques, however, are limited to use with a class of magnetic workpieces. In this particular study, the magnetic field was coupled with the conventional EDM plasma zone to test the hybrid process on Al-based metal matrix composites (MMCs). The machining parameters, for instance, peak current as well as duration of pulse-on were selected to nail down thereafter effects on the response parameters like the material removal rate (MRR) and the surface integrity. The experimental results show an improvement of 12.9% MRR and reduction in recast layer formation at higher spark energy in the magnetic field environment. As the experimental outcome implied that the MFAEDM imparted appreciable process stability, a highly efficient pertinent process of EDM with high quality of the machined surface could be accomplished to satisfy modern industrial applications.

Investigation of magnetic field-assisted EDM of composites

ABSTRACT The Electrical Discharge Machining (EDM) technique was performed under the magnetic field influence to determine the material removal mechanism as well as surface roughness (SR) of nonmagnetic material. This study presents an exploration of the hybrid EDM technique assisted by magnetic field, with an aim to improve process performance. Herein, magnetic field intensity, peak current, duration of pulse-on/off, tool electrode material, and SiC percentage distribution were opted as the machining parameters. The chosen parameters were analyzed for their effects on the material removal rate (MRR) and SR while machining of SiC-reinforced aluminum-based metal matrix composites. Taguchi methodology was adopted for optimization of process parameters to achieve better MRR and lower SR. The experimental results witnessed improved surface finish and enhanced material removal ability of the process and also inferred that the magnetic field-assisted EDM facilitated the process stability.

Magnetic Field Assisted EDM: New Horizons for Improved Surface Properties

The current research study for hybrid machining of Al-based metal matrix composites (MMCs) employs magnetic field coupled traditional electrical discharge machining (EDM) to address the manufacturing demands in aeronautics, automobile, medical equipment, etc. The input processing parameters, for instance, magnetic field intensity, pulse-on/off duration, peak current, variant of electrodes as well as workpiece were evaluated to determine their after-effects on the responses in terms of microhardness (MH) and recast layer formation while machining of Al-SiC composites. The experimental results show 22% decrease in the surface microhardness values and thinner recast layer formation at magnetic field coupled higher spark energy. The results demonstrate the process stability and exhibit a good accord with experimental verification.

On the thermal conductivity of bimodal SiC/A356 composites fabricated via powder metallurgy route

ABSTRACT The present study investigates the thermal conductivity of bimodal SiC particulate distribution in aluminum matrix composites fabricated via powder metallurgy route. The effects of the SiCp reinforcement size distribution and processing parameters such as sintering time and temperature on the thermal conductivity have been examined. The Box–Behnken experimental array was employed to identify the effects of selected variables on the thermal conductivity of the composite. A reasonable augmentation in the thermal conductivity was observed with an increase in sintering time and %volume fraction of fine SiC particulates. It has been demonstrated that the matrix doped with fine SiC particulates (37 µm) occupied interstitial positions and formed continuous SiC–matrix network resulting in minimizing the micropores that contributed for good thermal conductivity, that is, 235 W/mK. Scanning electron microscopy (SEM) and x-ray diffraction (XRD) were conducted to evaluate the microstructure architecture and interfacial phase formation.

Application of MCDM Techniques on Nonconventional Machining of Composites

This study has been carried out to assess the impact of electrical discharge machining parameters on the SiC-reinforced aluminum metal matrix composites. The criteria in machining process including electrodes material, current, pulse time, and dielectric medium were diversified to evaluate their effect on material removal rate (MRR), surface roughness (SR), and residual stresses. The residual stresses induced due to subsequent heating and cooling shocks during the electric discharge process are of primary concern while machining process. The magnitude of residual stresses induced on the machined surface was estimated via X-ray diffraction method. The process conditions that influenced the responses were recognized and optimized synchronically using multiple criteria decision-making and statistical techniques. In this study, analytical hierarchy process (AHP) and a multi-objective optimization analysis (MOORA) will solve process condition problem. This approach confers the combination of process parameter settings suitable for the machining of such composites.

Investigation of Surface Properties of Al–SiC Composites in Hybrid Electrical Discharge Machining

In this research study, hybrid AJEDM (abrasive jet-assisted EDM) had been employed on the aluminum–silicon carbide composite (Al–SiC) material with an aim to attain high surface finish along with the higher material removal rate and lower tool wear rate. SiC abrasive particulates mixed EDM oil was used as a dielectric medium for flushing from the center of the tool electrode. The input parameters, for instance current, pulse-on/off, dielectric medium, and tool hole diameter were considered. It has been observed in the research work that MRR is significantly affected by the machining parameters such as peak current, pulse-on/off as well as type of flushing conditions and MRR enhanced significantly with the increase in spark energy at lower pulse-off time whereas the flushing by dielectric mixed with SiC particulates lead to sharp reduction in MRR. However, surface finish improved steeply in SiC-assisted dielectric flushing conditions. But surprisingly, the tool erosion rate drastically reduced with SiC-assisted flushing of dielectric fluid along with thinner recast layer. The selected parameters like current, hole diameter, and pulse-on/off time showed insignificant effect on the TER and SR. Furthermore, the results were advocated with various SEM and EDS images.