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.
Machining of Inconel 718 with a defined geometry tool or by electrical discharge machining
Inconel 718 alloy is the most used nickel-based superalloy owing to its characteristics of excellent mechanical and chemical properties at high temperatures and relatively low cost in comparison with other alloys. Nevertheless, the mechanical properties and components with intricate geometric shapes usually lead to difficulty in machining this alloy. This article reports a literature review on the machining performance of Inconel 718 alloy using conventional machining processes as well as electrical discharge machining. Based on the literature review, it is possible to highlight that for conventional machining, non-uniform flank wear and notch at the depth of cut are the leading causes for cutting tool failure when machining Inconel 718. Abrasion is the prominent wear mechanism, followed by diffusion, adhesion, and chipping. Regarding the assessed literature, 65 % used cemented carbide as cutting tool material, 20% used ceramic cutting tools, and 15% applied CBN tools. For ED-machining, copper is the most used material as a tool electrode, followed by brass and graphite. Regarding the electrical variables, discharge currents applied are from 10 to 20 A, and the pulse duration varies from 50 to 200 µs. The thickness of the white layer, varying from 3 to 50 μm, depends directly on the combination of process parameters, which involves the variation of discharge current and pulse duration.
SR topography of plastically deformed Fe-Si bicrystals - observation in situ and post mortem
SR reflection topography was applied to study the interaction of slip dislocations with the grain boundaries in Fe-4at%Si bicrystals deformed by compression. Three experimental settings with either a white or monochromatic beam were used and the corresponding orientation contrast analysed. Dislocation transmission through the grain boundary was observed in bicrystals with favourable geometry of the slip systems.