MMM LECTURE NOTES FINAL.pdf

The use of a computerized nc system enabled large

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of hard alloys is a typical application of EDM drilling. The use of a computerized NC system enabled large numbers of holes to be accurately located Sawing. ED sawing, shown in below figure is an EDM variation that employs either a special steel band or disc. The process cuts any electrically conductive material at a rate that is twice that of the conventional abrasive sawing method. The cut produced has a smaller kerf besides being free from burrs. Cutting of billets and bars is a typical application
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Modern Manufacturing Methods Machining of dies and molds . EDM milling uses standard cylindrical electrodes. Complex cavities are machined by successive NC sweeps of the electrode down to the desired depth. The simple-shaped electrode (Fig. 5.19) is rotated at high speeds and follows specified paths in the workpiece like the conventional end mills. This technique is very useful and makes EDM very versatile like the mechanical milling process. The process solves the problem of manufacturing accurate and complex-shaped electrodes for die sinking of three-dimensional cavities shown in given figures. EDM milling enhances dielectric flushing due to the high-speed electrode rotation. The electrode wear can be optimized because of the rotational and contouring motions of the electrode. The main limitation in the EDM milling is that complex shapes with sharp corners cannot be machined because of the rotating tool electrode. the die sinking process. These numerous and time-consuming steps are greatly reduced using EDM milling as shown in below figure. EDM milling also replaces the conventional die making that requires the use of a variety of machines such as milling, wire cutting,and EDM die sinking machines
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Modern Manufacturing Methods Plasma Beam Machining Introduction When the temperature of a gas is raised to about 2000°C, the gas molecules become dissociated into separate atoms. At higher temperatures,30,000°C, these atoms become ionized. The gas in this stage is termed plasma . Machining by plasma was adopted in the early 1950s as an alternative method for oxy-gas flame cutting of stainless steel, aluminium, and other nonferrous metals. During that time the process limitations regarding the low cutting speed, poor machining quality, and the unreliable equipment were clear. Recently machining of both metallic and nonconductive materials has become much more attractive. An important feature of plasma beam machining (PBM), is that it is the only fabricating method that works faster in stainless steel than it does in mild steel. Machining systems In plasma machining a continuous arc is generated between a hot tungsten cathode and the water-cooled copper anode. A gas is introduced around the cathode and flows through the anode. The temperature, in the narrow orifice around the cathode, reaches 28,000°C, which is enough to produce a high- temperature plasma arc. Under these conditions, the metal being machined is very rapidly melted and vaporized. The stream of ionized gases flushes away the machining debris as a fine spray creating flow lines on the machined surface substantially higher than those of conventional single-point turning operation. Plasma machining systems are divided into plasma arc, plasma jet, shielded plasma, and air plasma
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  • Fall '12
  • JeraldBrevick
  • EDM, conventional machining processes, Jet Machining

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