STUDY OF MATERIAL REMOVAL RATE OF DIFFERENT TOOL MATERIALS DURING EDM OF H 11 STEEL AT REVERSE POLARITY
Electric Discharge Machining (EDM) is a non-traditional machining process that involved a momentary spark discharges through the fluid due to the potential difference between the electrode and the workpiece. In EDM, improper choose of the electrode material may cause poor machining rate (or) performance. This is due to material removal rate characteristics. Less material removal rate (MRR) needs more time for machining process and become waste which is not good for production. Hence in this study, the effect of input parameters of EDM process ie. electrode type, peak current, gap voltage, and duty cycle on material removal rate of H11 steel are experimentally investigated. A L18 Taguchi’s standard orthogonal array is used for experimental design. Conventional Copper (Cu) and powder metallurgy (PM) copper tungsten (CuW) are used as tool materials. It was found that conventional copper tool electrode gives maximum MRR and best parametric setting for maximum MRR was found at, Cu (99% Cu) tool electrode, 9 ampere current, 50 volts gap voltage and 0.92 duty cycle. ie. A1B2C2D3.
Optimization of Electrical Discharge Machining Process Parameters using SCM420 low alloy steel by Response Surface Methodology
Electrical discharge machining is a nonconventional machining process which enables machining of complex and intricate shapes, hard materials that are precise and difficult to machine such as heat treated tool steels, composites, super alloys, ceramics, carbides, heat resistant steels etc. The process involves spark erosion in the presence of dielectric fluid. In this work SCM 420low alloy steel is the material used for the machining purpose with electrolyte copper as tool. This work investigates effect of process parameters peak current (IP), Pulse on time (Ton) and gap voltage (Vg) on Material removal rate (MRR) and surface roughness (Ra). Response surface methodology is used for experimental design. The suggested model can be used in the different manufacturing firms by selecting right combination of process parameters to achieve optimal values of output responses.
Experimental investigation on migration of material during EDM of die steel (T215 Cr12)
Abstract This paper presents the Scanning Electron Microscopic (SEM) investigation on changes in chemical composition of resolidified layers of both the tools and the workpieces as well as debris. An investigation has also been made on variation of micro-hardness, depth of resolidified layer and heat affected zone (HAZ) with pulse current and electrode rotation. This change in chemical composition occurs due to migration of material from either of the electrodes during electro-discharge machining of high carbon high chromium die steel (hardened) with rotating copper-tungsten tool electrode. The machining characteristics of the material depend on the various machining parameters like discharge current, pulse duration, voltage, dielectric and electrode materials. The rotation of electrode during machining also contributes towards these. The experiments were conducted by varying discharge current and electrode rotation to study the effect of these parameters on alloying of tool and workpiece surfaces. An effort has also been made to compare these results with that of stationary electrode. The experiments were statistically designed and a mathematical model of the process has been developed. It is found that appreciable amount of elements has migrated from the tool electrode to workpiece and vice versa and got alloyed in the resolidified layer. The chemical composition of debris also changed due to the pick up of elements from both the electrodes.