An oil-based dielectric fluid allows a smaller spark gap (i.e., the gap between the wire electrode and the workpiece at the time of electrical discharge) than a water-based fluid. This facilitates precision machining of narrower slot widths and smaller corner radii. These wire EDM machines are equipped with Makino’s newly developed SPG II machining circuit that provides significant improvements in best surface finish and finish machining efficiency. A surface finish of 0.2 mRz is obtained under standard machining conditions for 20-mm (0.79") thick workpieces measuring up to 100 x 100mm (3.93" x 3.93").
Another advantage of an oil-based dielectric system is that there is no softened HAZ layer produced when processing carbide, nor will any surface corrosion occur on machined surfaces. In long-run applications where the machined parts must remain submerged for extended periods, this can be critical in controlling corrosion or oxidation layers on parts that are susceptible to these effects. When cutting carbide materials in deionized water, for example, an electrolytic corrosion can occur. These materials can range from various grades of tungsten carbide to traditionally recommended EDM-grade carbides. When this happens, the result is cobalt binder depletion in the workpiece. By using oil dielectric instead of water, this electrolytic damage is eliminated, thus extending edge quality, edge life and overall cutter life. Oil dielectric fluid is well suited to the machining of hardened materials and polycrystalline diamond (PCD).
In carbide machining testing performing as burns, the UPV machines have proven to be up to 22 percent faster than Makino’s current water-based machines, and up to 78 percent faster than Makino’s prior oil-based technology, with good sealed flushing.
Both UPV machines are fitted with PICO precision wire guides that have a proven record of high performance on Makino’s DUO and Uj-Series WEDMs. The UPV-3 has XY-axis travels of 14.56" x 10.63" (370 x 270mm), while the UPV-5 provides XY-axis travels of 21.65" x 14.56" (550 x 370mm).