Re: Home-built EDM

Here is some info on how the EDM process works.


http://www.edm-products.com/Dielectrics/ifase/table_of_contents.htm








--- In CAD_CAM_EDM_DRO@yahoogroups.com, "turbulatordude" <davemucha@j.
..> wrote:

> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Marcus and Eva"


> <implmex@a...> wrote:


> > Hi All:


> > You don't want much conductivity in the dielectric.


> > What you do want is just enough conductivity and close enough


> proximity


> > between the workpiece and the electrode that a controlled amount


> of current


> > at a predetermined voltage will jump the gap and knock a bit of

the

> > workpiece away as it does the jump.


> > The dielectric is ionized locally in the process, both by the


> energy of the


> > discharge and by the contaminants that are produced by the

erosion

> of the


> > workpiece and electrode.


> > Commercial wire EDM's go to great lengths to get the ions back

out

> of the


> > dielectric (they mostly use water as a dielectric) so it won't be


> too


> > conductive.


> > The conductivity should be such that several amperes at 30 odd


> volts is


> > needed to traverse a gap of roughly 0.001", and should stay that


> way as much


> > as possible throughout the burn.


> > Dumping salts into the water will make it far too conductive to


> work.


> > Cheers


> >


> > Marcus


>


> This is espically true for an RC circuit. the conductivity of the


> dielectric can prevent the cap from charging.


>


> In this months EDM rag of the trade, they are offering cleaning of


> your EDM fluid. you ship out your old stuff and they will clean it


> and return you stuff 'as good or better than new'


>


> For us garage and basement guys, water works acceptably. and as

Jon

> advised, some solutions work much better.


>


> Dave