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Because EDM erodes metal with electrical discharges instead of with chip machining cutting tools, the hardness of the workpiece does not determine whether or not a material can be machined by EDM. A relatively soft graphite or metallic electrode can easily machine hardened tool steels or tungsten carbide. This is one of the many attractive benefits of using the EDM process. Rather than machine a workpiece before heat treating, it can be EDMed afterward. This eliminates the risk of damage or distortion which could scrap an expensive workpiece during heat treating.
The basic principles of wire-cut EDM are essentially the same as diesinking EDM described above. The major difference is that instead of using an electrode with a complex shape, in wire EDM the electrode is a simple wire, typically .006" to .012' diameter, which follows a horizontal path through the workpiece. Instead of using dielectric oil as in die-sinking EDM, wire EDM uses deionized water.
DEVELOPMENT OF EDM IN THE MIST
This paper examines the machining properties of a new EDM process which takes place in a sprayed mixture of gas and liquid. It, namely EDM in the mist or mist EDM, does not require a tank for working fluid like in conventional EDM. The most distinctive feature of it is non-electrolytic machining even if electrically conductive water is used as a fluid. Therefore, water or water soluble cutting or grinding oil can be used for working fluid so it will become easier to combine EDM with traditional machine tools.
EDM BY POWDER SUSPENDED WORKING FLUID
This paper presents some effects for finishing electrical discharge machining which uses powder in working fluid. Appropriate powder use gives 0.8 mmRmax surface with the area of 25 cm2, and also shortens the finishing time extremely. It is verified in some experiments that powder suspension brings about stable EDM even under micro-electrical condition because of large gap distance and good dispersion of discharge current.
THE PROPER CHOICE OF HYDROCARBON DIELECTRIC FLUID FOR EDM APPLICATIONS, A COMPREHENSIVE COMPARISION
The commercially available large variety of dielectric fluids for EDM applications mades the choice rather difficult. Are there any advantages or disadvantages using one or another product? This paper describes a comparison test of 35 different hydrocarbon dielectric fluids in machining various metals using several different electrode materials.
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