Wire EDM uses deionized water as the dielectric medium compared to Vertical EDM’s that use oil. The dielectric system includes the water reservoir, filtration system, deionization system, and water chiller unit. During machining, the dirty water from cutting is drained into the dirty, unfiltered side of the dielectric reservoir, where the water is then pumped and filtered to 3 microns through a mineral bed vessel, and returned to the clean side of the dielectric tank. When the vessel approaches its capacity and reaches a set pressure, the unit automatically back flushes the material (swarf) into a separate decant tank, where the material decants (settles) in the water. This is an exclusive ONA patented maintenance free, lifetime filtration system. You never have to purchase paper filter elements or worry about their disposal. This equates to tremendous cost savings per year.
Following filtration, the clean water is measured for conductivity, and if required, automatically passes through a vessel that contains a mixed bed of anion and cation beads. This mixed bed resin (ion exchange unit) controls the resistivity of the water to set values.
Note: Deionized water is an efficient insulator. Untreated water is a conductor and would cause unstable cutting, wire breaks and not be usable in the EDM process. The clean, filtered water now flows into the clean side of the dielectric reservoir and proceeds to the cutting area. Used water is drained and returned to the unfiltered, dirty side of the dielectric reservoir to complete the cycle. A water chiller is also provided as standard equipment to keep the dielectric, workpiece, worktable, control arms, and fixtures thermally stable.
The quality of the water is constantly measured. During the cutting process the chips from the material that is being eroded, gradually change and increase the water conductivity level. When this level becomes too high, the water is automatically directed to pass through the deionizing resin.to bring it to the correct level. Resistivity levels of the water are set at the control according to the cutting requirements of the workpiece material being machined. Another additional cost savings and benefit ONA provides is their patented “EKOADD”. By using this additive, the polarity of the eroded particles in the dielectric are “neutralized” causing them to cling and be joined together. This additive extends the life of the resin by 50% or more, and also helps clean the precision guides and power feed contacts while providing cleaner water.