Tips for Controlling Oxidation and Pitting on a Wire EDM
Additives, machine settings, workpiece materials and current technology are factors in avoiding common problems with unwanted rust and surface defects.
Additives do help in controlling oxidation and pitting of a variety of materials. These products help a great deal when cutting a workpiece with pre-polished surfaces.
Set the water conductivity to 5 microS or less, which is typically recommended for carbide, PCD, titanium, and fine finishes (<10 micro inches). This will also help keep bluing to a minimum on older non-anti-electrolysis generators.
Check water pH. Acidic detergents used to clean parts and tank will have a dramatic effect on parts rusting and will reduce the life of the deionization bottles.
Mix Workpiece Materials
With all the new and old types of alloys available, material incompatibility may cause surface issues. However, EDM field technicians have yet to document an instance where this situation has occurred.
Most current wire EDMs are equipped with Anti-Electrolysis generators, some better then others. It basically comes down to how good the technology is and how fine of a surface finish the generator is capable of producing. A machine that is capable of producing a super fine finish (< 5 micro inches) can generate optimum surface integrity.
One example is the GF AgieCharmilles CUT 1000 that can machine parts with zero corrosion. The CUT 1000 is available in an oil version. With this feature, there is absolutely no electrolysis, corrosion and virtually zero recast.
A shop specializing in wire EDM for large mold components now offers EDM “turning” of small, intricate parts. Despite the potential risks involved in early adoption of new technologies, the shop believes this practice gives it a leg-up on the competition and lets it gain experience with alternative machining techniques before offering them to customers.
A new breed of power generators for wire EDMs has options for reducing, even eliminating, one of the unwanted side effects of this very versatile metalcutting process.
By systemizing die making into repeatable steps, Dies Plus, a division of Otto Engineering, is using its machinists to effectively make dies. This solution relies on a paperless color-coding system to convey the tolerances machinists need to hit in order for tool and die makers to do the final fitting.