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Tungsten carbide is one of semented carbide materials , that are known as metal carbides. Tungsten and carbon are the elements of WC, W 2C and W 5C3 that is
stable only at higher than 2535°C. Among above mentioned three combinations of Tungsten, the stability of mono Tungsten
carbide (WC) that briefly named Tungsten carbide is better, so, it is more important. The plastisity of Tungsten carbide is high and in comparision with steel its modulus
of elastisity is three times bigger. Its hardness is bigger than that of steel, even in very stream conditions, so that it doesnt's make any noticable changes at high temperature. Because of its high resistance to wear and good shockness, it is used in various kinds of carbide dies and
cutting tools. Although the machining of Tungsten carbide with conventional methods is almost successful in
comparision with machining of Silicon
carbide, but because of complexity of the shape of workpiece and high needed accuracy in machining, the conventional machining methods cannot achieve them.
Among non-conventional machining methods EDM is an especial case in machining of cemented carbides. With consideration of instability of ED
machining of Tungsten carbide process, this paper tries to give some instructions
that leads to more stable machining process. About the machining of different grades of Tungsten - carbide, open circuit pulses are more than 500/0 and Arcing are
less than 150/0 with different pulse durations. In these materials, increasing the
pulse duration, increases machining instability. In nearly all grades of
Tungsten- carbide, the size of the grains on the machined surfaces become bigger and
show the gathering much more resolidified materials. The presence of cobalt nearly on everywhere of the machined surface
patterns, may be because of resolidification
of cobalt and recombination with Tungsten or Tungsten - carbide on the surface of the workpiece. The elimination of the cobalt
and Tungsten together from arcing area,
make holes which are suitable places for carbon to remain and grow and afterwards make arcing.