We are currently using COMMONWELTH 244 dielectric fluid and have been since over 10 years. Can anyone tell me if it needs to be changed or are the filters able to clean it up and last forever? We are running MITS EX type and have heard that synthetic is much healthier on the human skin but man is it costly. any help is appreciated
As good and long-lasting an oil as Commonweath 244 is, 10 years old is likely way past its prime, even if you don't do a lot of roughing. It's good that you keep the oil clean with regular filter changes, but like the oil in your car, even if itís clean, it breaks down from use. Mostly from heat but also from oxidation (from water created by condensation every time you start a cold engine) and various chemicals changes that occur along with contaminants that cannot be filtered out. As it breaks down, it loses its lubricity and it must be changed.
Similar things occur to EDM oils too, expecially since the temperature of the spark is thousands of times higher than that of an auto engine. As an EDM oil ages, there is also oxidation, chemical changes and contaminates that can't be filtered out, but when an EDM oil breaks down, it loses its dielectric strength, an important attribute in efficient and predictible machining.
I suggest you contact your local supplier and tell him you'd like an education on EDM oils - how they work and how long they can last. Through this you will also learn if you need a synthetic or not (sorry 'bout their prices).
Hope this helped,