EDM Electrode Cutting Technics

[roland_1]

Hi

I don't do so much of EDM sinker but I saw different techniques of electrode cutting in two companies. Its not important to me but I would like to hear what others think. So if you want you are welcome to share.

Mainly, in company where I was we would design electrode with overburn size and then in programming just cut it with negative stock to leave for overburn in both x-y and z. that was completely logical to me.

But now I saw company where they cut electrode without negative stock to leave at all. but thing is that they put just smaller diameter value for tool in program (which is double then desired ovrerburn/means overburn comp on radius). but they don't compensate nothing in Z. If I try to imagine cutting in 3D toolpath that looks like distorted geometry shape to me.

What you guys think about that? What are your practices? If I think there is possibility to even do it on third way for example to scale electrode. somebody tried that?

[Redfire427]

Scaling will definitely not work. Spark gap is constant whereas scaling your model will totally distort the spark gap.

 

I have always programed with negative stock. I just extract the surface that comprise the electrode area and then machine it with negative stock on all areas. The only difficulty is when programming with a sharp corner tool. You cannot go to a negative stock condition with a sharp corner tool on a 3D toolpath. The work-around here is to program the tool with a corner radius equal to the spark gap.

 

Carmen

[Millertime]

Negative stock to leave on all surfaces.If you comp off of the tool dia. you will not get and exact offset for youre overbun on fillets and irregular shaped surfaces commen in moldmaking.

[roland_1]

Yes, I also did neg. stock to leave on all surfaces when I was programming electrodes. I don't know what these guys are doing. only thing that this looks much easier to program. but interesting thing is that I just checked one of trodes, and the one with shape of half cilinder. on that shape destortion should be obvious but on comperator it is perfect semi cilinder. so there must be so comp. in Z. or is cheating on pickup.

[toddm]

we mainly design electrodes already with overburn subracted from the electrode. this way we cut at zero, leaving tool libraries standard.

on ocassion there are electrodes that cannot be offset in soildworks, then we just subract the overburn from the cutters....it makes all small difference on the geometry, but we like to keep Z zero , at zero.