Version 1.0, August 31, 2001, Copyright, Hugh Jack 1993-2001

58.1 WIRE EDM

 

· A thin wire of brass, tungsten, or copper is used as an electrode.

 

· Deionized water is used as the dielectric.

 

· The process is similar to standard EDM,

 

 

 

· Slowly cuts groove in shape of wire.

 

· Wire is consumed and is slowly fed.

 

· This process is much faster than electrode EDM.

 

· Machine speed is,

 

 

· Higher currents, and lower rest times increase the speed of this process.

 

· Relations between groove width and speed are shown in the graph below.

 

 

· This process is well suited to production of dies for plastic molding, progressive dies, etc.

 

· Summary of EDM characteristics,

  1. - mechanics of material removal - melting and evaporation aided by cavitation
  2. - medium - dielectric fluid
  3. - tool materials - Cu, Brass, Cu-W alloy, Ag-W alloy, graphite
  4. - material/tool wear = 0.1 to 10
  5. - gap = 10 to 125 micro m
  6. - maximum mrr = 5*103 mm3/min
  7. - specific power consumption 1.8 W/mm3/min
  8. - critical parameters - voltage, capacitance, spark gap, dielectric circulation, melting temperature
  9. - materials application - all conducting metals and alloys
  10. - shape application - blind complex cavities, microholes for nozzles, through cutting of non-circular holes, narrow slots
  11. - limitations - high specific energy consumption (about 50 times that in conventional machining); when forced circulation of dielectric is not possible, removal rate is quite low; surface tends to be rough for larger removal rates; not applicable to nonconducting materials