An intelligent and automated system for EDM hole drilling of super alloys
This paper introduces an intelligent and automated system proposed for EDM hole drilling of super-alloys in manufacturing and re-manufacturing stages of products used in aerospace, die/mold and medical surgery. The system is a user-friendly computer-based program, which guides the end-user in order to perform sustainable and effective process. To accomplish the goals of the work, a well-planned workshop tests have been performed via drilling of micro and macro-scale holes (0.4-3 mm) on Ti-6AI-4V and Inconel 718 alloys, which are commonly used in aerospace industry and medical sector for manufacturing of highly critical components. The experimental data was refined and analysed using ANOVA to obtain parameter's relations and mathematical modelling for optimisation. ANFIS has been adopted to correlate the EDM hole drilling parameters (i.e. pulse current, pulse duration/interval, capacitance, material removal rate, electrode wear and surface roughness) for fulfilling reliable, cost/time effective and efficient hole making operations.
Effect of SiC and rotation of electrode on electric discharge machining of Al–SiC composite
Abstract Metal matrix composites (MMCs) contain certain amount of secondary reinforcement, which makes it difficult to machine with conventional cutting tools and methods. The present study analyses the effect of electric discharge machining (EDM) parameters namely polarity, current, electrode material, pulse duration, and rotation of electrode on metal removal rate (MRR), tool wear rate (TWR) and surface roughness (SR) value in EDM of Al–SiC MMCs with 20 and 25 vol.% SiC. Irrespective of the electrode material, polarity of the electrode and volume percentage of SiC, the MRR increased with increase in discharge current and for a specific current it decreased with increase in pulse duration. Increase in the volume percentage of SiC had an inverse effect on MRR, and positive effect on TWR and surface finish. Increasing the speed of the rotating electrode resulted in a positive effect with MRR, TWR and better SR than at stationary. Optimum parameters for EDM drilling were also developed to summarize the effect of machining characteristics such as MRR, TWR and SR.
American Insurgents, American Patriots: The Revolution of the People
This is a story of rumour, charity, vengeance, and restraint. "American Insurgents, American Patriots" reminds us that revolutions are violent events. They provoke passion and rage, a willingness to use violence to achieve political ends, a deep sense of betrayal, and a strong religious conviction that God expects an oppressed people to defend their rights. The American Revolution was no exception. A few celebrated figures in the Continental Congress do not make for a revolution. It requires tens of thousands of ordinary men and women willing to sacrifice, kill, and be killed. Breen not only tells the history of these ordinary Americans but, drawing upon a wealth of rarely seen documents, restores their primacy to America's road to independence. Mobilizing two years before the Declaration of Independence, American insurgents in all thirteen colonies concluded that resistance to British oppression required organized violence against the state. They channeled popular rage through elected committees of safety and observation, which before 1776 were the heart of American resistance. "American Insurgents, American Patriots" is the stunning account of their insurgency, without which there would have been no independent republic as we know it.