Copper Tungsten Properties & DC Arc Resistance
If you ask experienced EDM technicians about their most most expletive-inducing, EDM related frustrations, you can bet pitting will be up there among the top five.
Pits happen when sludge made up of the worn electrode material and the removed workpiece material is not properly filtered out of the dialectic fluid. When enough particulate builds between electrode and workpiece, it can convert the AC current to a DC current. Acting like an electrode, this waste attracts a spark, which then arcs across the fluid and creates a concentrated discharge, ultimately causing a pit in the material.
DC arcing has the potential to undo months’ worth of lengthy, careful preparation in a matter of cycles as it often goes completely undetected until it’s too late. The most prevalent cause of pitting is poor flushing conditions, and machinists are necessarily preoccupied with one micron filtration systems and software that can respond to the detection of DC current and adjust cutting parameters accordingly.
How do Tungsten Copper Electrodes Improve Conditions?
Sometimes, however, poor flushing conditions can be hard to avoid–especially for particularly difficult burns. And in these situations, a copper tungsten electrode can be hugely beneficial. Pure copper has such remarkable structural integrity that it can produce exceptional surface finishes, even without specialty polishing circuits. It’s general resistance to DC arcing combined with the high melting point and density of tungsten make an electrode with unmatched wear resistance.
Although EDM is often thought to be a process that produces no direct or macro force, the thousands of tiny sparks the material is subjected to do have an affect on overall production. The structural integrity of a material determines its ability to withstand these violent micro forces and ultimately the quality of the workpiece. An electrode material with unparalleled wear resistance, notable resistance to DC arcing–even in poor flushing situations–can mean the difference between a job well done and a job scrapped.
For more on copper tungsten blanks for Sinker EDM applications, download our free white paper!