PARAMETRIC OPTIMIZATION OF Al-SiC 12 % METAL MATRIX COMPOSITE MACHINING BY ELECTRICAL DISCHARGE MACHINE
In the present study, pure aluminium alloy is mixed with 12% SiC on weight basis to fabricate the metal matrix composite (MMC) material. The objective of this paper is to investigate the effect of process parameters such as pulse on time(Ton), peak current (Ip) and flushing pressure (Fp) on metal removal rate (MRR), tool wear rate (TWR) and surface roughness (SR) during electrical discharge machining (EDM) of Al-SiC12% MMC .The experiment is followed by Central composite design (CCD) method under different combination of process parameters .In this paper Response surface methodology (RSM) is used to develop the mathematical model and to correlate the process parameters with the response. Also Analysis of Variance (ANOVA) technique is used to check the significance of the model and confirmation test is conducted to compare the experimental data with the predicted data to identify the effectiveness of the proposed method. From the main effective plot it is found that peak current is the most significant parameter among the other. Further the morphology study of the composite is carried out by the Field emission Scanning electron microscope (FESEM) of the surface after machining to make a relation with the model.
Influence of dielectric and machining parameters on the process performance for electric discharge milling of SiC ceramic
Silicon carbide (SiC) ceramic has been widely used in modern industry because of its superior mechanical properties, wear, and corrosion resistance even at elevated temperature. However, the manufacture of SiC ceramic is not an efficient process by conventional machining methods. This paper employs a steel-toothed wheel as the tool electrode to machine SiC ceramic using electric discharge milling. The process is able to effectively machine a large surface area on SiC ceramic. To further improve the process performance, three kinds of emulsion are proposed as the dielectric in this paper. The effects of dielectric, tool polarity, pulse duration, pulse interval, peak voltage, and peak current on the process performance such as the material removal rate (MRR) and surface roughness (SR) have been investigated. Furthermore, the microstructure of the machined surface is examined with a scanning electron microscope (SEM), an energy-dispersive spectrometer (EDS), and X-ray diffraction (XRD).
Bodies Politic : Disease , Death and Doctors in Britain , 1650-1900
In spite of its intellectual, literary and comic brilliance, this book contains a dark and disturbing, but revealing, message. In some ways, my melancholy reading of Bodies Politic has inevitably been shaped by Roy's recent untimely death. Roy Porter was without doubt the finest social historian of medicine this country, or indeed the world, has produced. Expansive, humorous, intelligent, and incisive, his broad range of historical works has excited and educated several generations of students of history over the past thirty years. His death leaves an unfillable void within the global history of medicine. At the same time, however, this book itself, completed well before his death, is haunted by elements of despair and uncertainty that should make us carefully reconsider not only the purpose and direction of our professional inquiries but also our own mortality.