Hi Zahnrad Kopf:
I'm curious; have you had good results with wire EDM cut carbide for cutting tools?
I've always been disappointed with their longevity compared to ground ones.
There have been a few threads on PM where this has been discussed, and one in particular where Carbide Bob and I got into a bit of a doctoral dissertation about root cause but I can't find it again.
Short version is that the water dielectric leaches the cobalt out from around the corner tungsten carbide grains leaving them hanging in space where they get wiped off and booger the cutting edges.
So the serious cutting tool and punch tool guys use oil dielectric in their wire EDM machines.
When I was still young and cocky, I thought it was all bullshit...now not so much anymore, having wasted many hours on fancy cutting tools that didn't perform for shit because all the cutting edges crumbled prematurely.
I've tried a few approaches, and the best I've been able to do with carbide is to wire the shape a tiny bit oversized (tenths), glass bead them and then surface grind 0.002" to 0.005" off the rake to hopefully knock off the loose tungsten carbide grains right at the cutting edge, but I still have never been thrilled with what I ended up with.
I went back to cobalt HSS and seem to get better performance out of it than I can get from wire cut carbide.
My GO TO grade now is REX T15...tougher than a woodpecker's lips and wire cuts just fine; I make pretty much all of my form tools out of it now.
Food for thought before you spend a lot of money on carbide!
Cheers
Marcus
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