ECM for hobby use?

[medved]

Hello to all.



I am intrested in using ECM (electrochemical machining) for hobby use. As I understand it easier to control conditions in ECM than it is in EDM, so I think ECM is a first choice for hobby experiments.
What is so attractive in these techniques is that they are "non-contact" techniques, meaning that it is possible to machine parts with hobby mills which otherwise arent rigid and strong enough to work with classic(milling)techniques.

Has anyone here experiences with ECM?


My idea is to use electrolyte soultion that ACCELERATES passivisation of the anode(=workpiece) together with grinder which removes thin unconductive film and so SELECTIVELY causes removal of material only on spots where you want it to be removed. So this would not be "trully non-contact" technique but more ELECTROCHEMICAL GRINDING, yet my idea is to use common mill-bit as a cathode and grinder in one(instead of special -and I guess expensive grinders- made of condcuctive material). Mill-bit would remove only thin nonconductive film and let the electrolyte do the job of actually removing hard material on so exposed surface. Precondition for this is of course that this thin film is actually soft enough to be easily removed with mill(and is not equaly hard or even harder than workpiece material itself). Another precondition is the abbility of steppers/servos to do small enough steps, so that only upper layer=unconductive film is removed and not the workpiece material itself(this might be a real problem ---how thick is such film actually?)
Can anyone comment on this idea - is it feasible?


As I understand water and (sea)salt isnt appropriate electrolyte because it doesnt induce passivisation on workpiece. The only salt I could find in the literature was NaNO3 -Sodium Nitrate. Are there some more salts that do induce passivisation and arent exocitc, expensive, poisonous, explosive or otherwise dangerous- that is, they are easily available?


Thanks for any feedback

[budP]

Hi
I sure would like to know why you would want to use this process
It is really expensive, high specific energy consumption (about 150 times that required for conventional processes), several years ago we tried this just for resurfacing and I still have the transformers, 55 volts @ 200 amps, high dollar stuff.
another high cost item was the centerfuge to clean the electrolyte

budP