Investigation of Machining Characteristics of AA7050/Gr/CNT Composites
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Nagaraja T. K
Sasidhar Jangam
Abstract
In this investigation, an effort was made to use the Electric Discharge Machining (EDM) technology to process the hybrid composites AA7050/Gr/CNT. The tool wear ratio (TWR), material removal rate (MRR) and surface roughness (Ra) were detailed as outcomes. The experimental runs were planned exploiting the Taguchi mixed orthogonal array. The composites were made through the stir casting technique and machined by varying current, tool materials, powder concentration, and pulse on time. The results showed that improvement in MRR was due to the bridging effect, TWR depends on the physical property of the electrode and Ra depends on the flushing of the machined debris. The densification of plasma channel and machined debris occurred at the higher parametric value of current and Pulse on time. The microstructure of samples machined with a brass tool exhibited cracks, craters, globules, remelted layers, and black spots, indicating thermal and chemical effects of the EDM process, while aluminum tool machining showed deeper craters, uneven surfaces, and clustered globules, attributed to aluminum's properties affecting material removal and solidification behavior, whereas Copper tool machining resulted in larger globules due to its high thermal conductivity, along with craters, pinholes, remelted material, cracks, and pits. The ANOVA table revealed that Pulse on was the supreme process parameters trailed by the powder concentration. The PROMTHEE revelaed that with 5% Al2O3 integrated dielectric medium, composites machined with 7A current and 20µs Tonne using the brass tool provided the best machining performance.
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