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Can water be too clean?

bob

Titanium
Joined
Aug 12, 2002
Location
Regina, Canada
The meter on my old Elox never worked but generally machine works ok so never bothered to fix it. Came across a new meter installed was reading about 30 so I ran the filters and resin got it down to 12. All hell breaks loose. Machine stutters and breaks wire, wtf. Turned off resin and suffered through till reading came back up and machine worked like before. The result was sure not what I expected just wondering if I don't understand the theory.
Bob
 
Hello!

I personally never seen anything negative while the water was "too clean". Our Mitsubishi machines have a bad relay, so they ran the resin pumps all day. It's not rare that the water is bellow 15 microsiemens (we tend to froget shut the pumps down manually if the water is good). But it can be the case, some older machines have a way worse tolerance for water conductivity.
 
Hi Bob:
Yes it can.
Most people are not aware that pure water is a very poor conductor and it's important to know that.the water in a wire EDM has several functions, one of which is to act like a dielectric fluid in a capacitor.
So the conductivity of the water needs to be maintained within a range such that the current can jump the gap from the wire to the workpiece.

This is done by leaving enough ions in the water to bring the dielectric constant into the correct range, then stripping out the excess ions in the water as they are created by the cutting process and by the introduction of any conductive contaminants like salts into the water.

So the DI system is constantly trying to strip out enough of those ions to bring the conductivity of the water into the proper range; the conductivity is measured by a probe and water is diverted into or out of the DI circuit which binds the ions produced by cutting, into a tank filled with resin beads doped with its own ions that are trapped in the resin and cannot escape into the water.
They will grab any ions of opposite electrical charge, gradually poisoning the resin bed until it cannot hold any more ions and needs to be replaced.

So the water needs to be kept just the right amount of dirty: too clean, and the water is not conductive enough; too dirty and the water is too conductive.
Both conditions will create the kinds of problems you're describing with stalled cuts and broken wire.
You need to be in the conductivity range where the water is "just right" for your generator.

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining
 








 
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