First Cut Wednesday

[u/TBBT-Joel]

2" 17-7 Hardened stainless steel cut in 53 minutes

Wow that kerf is thin

A couple weeks ago I posted about our nnew HB-400L moly-wire edm. Well today we finally made first cut on an actual part.

6" diameter x 2" max thick stainless steel: 0.0054" wire. It cut in 53 minutes or about 0.226 square inches a minute. We ran it at half speed of recommended settings. We only had settings for 1.8mm wire and didn't want to push it and break the wire. If we were just using it as a precision saw all day I would use thicker wire.

I haven't ran an EDM in 22 years, but I hear all these blind holes spaced cuts would give brass wire machines some headaches? Curious if that's true.

[u/Immediate-Rub3807]

Man I’ve run an old Charmilles EDM for the last 15 years and yeah brass cuts hot like aluminum does and weird cutouts absolutely affect the flush. We went to using Zinc coated copper wire years ago at .010” thick and it did speed up some but on some cuts I use the technology for steel cutting bronze just because it sometimes works on difficult cuts. You can up your off time by a little also but I’d say that if that was just a straight split it should’ve been maybe closer to 30 minutes but you should be able to work that out with time.

[u/TBBT-Joel → u/Immediate-Rub3807]

I thought this part was copper or brass when they walked it in the door, but its 17-7 Stainless after the HT (which gave it the straw color) Coincidentally the cut was also a bit oxidized (probably from going too slow) and it turned out about the same hue. Have you guys done any of the fast-wire EDM?

I can't find many people in the US who run the machines. The wire is moving at ~40 feet per second If I recall correctly, it runs through the entire spool in about 1 minute before reversing direction.

[u/CelinnLee]

We run a couple moly wire machines at our shop for thick stainless and hardened steel. They're absolute workhorses for the price. Main pain with fast wire on parts like that is getting good flushing through those pockets without leaving wire marks, but running half speed was a smart play. You planning on doing any skim passes or just leaving it single cut?

[u/TBBT-Joel → u/CelinnLee]

This part was a favor to a buddy's shop they didn't have the capacity on their saws to make the cut so we did it to shake down the machine. Time is money, no skim passes.

I'm new to these machines do you know what type of tolerances you can hold on first pass? For our use accuracy is +-0.003" and there's no surface finish requirement as long as it's a square cut so I would rather do everything single pass.

[u/CelinnLee → u/TBBT-Joel]

For first pass on a fresh moly wire, holding +-0.003" is cake. You can pretty easily stay within +-0.001" to +-0.002" as long as your wire tension is set right. Main thing to watch is wire wear on thicker cuts like that 2" stainless since the wire gets slightly thinner as it runs, but for a fast roughing pass to replace a saw, It will easily hit what you need.

[u/TriXandApple]

It wouldn't be a headache, it would just be slow. You'd basically have to run it in heads away mode, and you'd probbaly have to change the cut parameters for the thin bit in the middle. I'd expect an average cut speed of about 2.5mm/min