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Help Choosing CNC for Copper Electrode cutting

007Rob

Aluminum
Joined
Sep 24, 2015
Hi Everyone,

I work for a small mold shop that has been busier than ever for the last 6 months, and it looks like this next year is on track to be even crazier.

We're looking at picking up a couple new machines to support the increased workload, and to also improve our efficiency. Like many shops we've been finding it hard to find skilled help as we grow and we're hoping we can make up some of the difference with automation and new technology. Will be making another thread in the near future regarding our search for a 20x40 class VMC (or?) for mold base machining.

Our current electrode machine is a Mikron HSM500 high speed CNC, it has an HSK40 spindle w/ 40k rpm and holds 36 tools. This machine shares duties between cutting copper electrodes to keep our sink edm machines running, and hard/soft milling of core and cavity inserts along with any other mold parts that come along.

We are happy with the performance of this current machine, just need to increase capacity and would like to find a machine to dedicate to cutting electrodes only. This would free up the HSM500 for more hard milling jobs and other work and also offer other advantages like not having to share tools between copper and steel cutting etc.

We would also like something that can be used with a pallet changer or possibly some type of robotic parts changer. It looks like most of the dedicated electrdoe machines are meant to be used this way, since they have smaller table sizes I don't see how else you could keep them running overnight unless you have really long running electrodes?

We aren't using any real automation in the toolroom right now, but we like the idea of adding a CMM for checking electrodes and connecting with our sink EDM in a "cell" type of arrangement. I will admit that's probably a little ambitious but we would at least like the option of growing into this type of setup in the future.

I sent off an email this morning to our Mikron guy, I see they have an "HSM200" machine which looks like it could fit the bill. Small table, automation friendly, 50k rpm. Sounds great, but would still like to explore what else is available.

Some other names we are looking into:

Roeders - Comes highly recommended by someone here. Have them coming by soon
Makino - Also have a salesman coming by to talk with us
Okuma - do they have anything small enough?
??????


There's so many different machines out there, wondering if there's any other manufacturer we should be looking at, or any other advice? Thanks in advance!
 
Roku. Maybe Brother, not sure what spindle options they have that go up into the range you want.
 
If you have that much electrode work, maybe time to look into one that is sealed up for graphite machining. They can still be steel capable machines if you like. Makino has some graphite options in their line up.
 
Roku. Maybe Brother, not sure what spindle options they have that go up into the range you want.

Thanks, I'll take a look at the Roku machines. I badly want a Brother to play with, but not sure if they're really suited for the long run times with smaller tools at high rpm.

If you have that much electrode work, maybe time to look into one that is sealed up for graphite machining. They can still be steel capable machines if you like. Makino has some graphite options in their line up.

Our Mikron was originally built as a graphite machine it's the "mold master" version but we strictly use copper for our electrodes so the dust extractor was removed and just run a mist extractor instead.
 
Roku. Maybe Brother, not sure what spindle options they have that go up into the range you want.

I love Brother, but their available highspeed spindles and surfacing may not be a good fit here. For mold base stuff, the Okuma genos 560 is a fatastic looking machine. We work with a mold shop that has one and they churn out some quality work, even with its somewhat limited spindle. More of a brute force spindle, than speed. I have to think that you should weigh your needs and perhaps a smaller 5axis machine could help alleviate some of your EDM needs for smallish inserts/subinserts. I may be way off base with the price of entry... But those Mikron HSM500 are pretty pricey too right?
 
A Willemin-Macodel 308S2 is only a bit smaller work envelope than the HSM200. 38S2

What's your biggest chuck/electrode size? Around ITS50 or bigger stuff?
 
I love Brother, but their available highspeed spindles and surfacing may not be a good fit here. For mold base stuff, the Okuma genos 560 is a fatastic looking machine. We work with a mold shop that has one and they churn out some quality work, even with its somewhat limited spindle. More of a brute force spindle, than speed. I have to think that you should weigh your needs and perhaps a smaller 5axis machine could help alleviate some of your EDM needs for smallish inserts/subinserts. I may be way off base with the price of entry... But those Mikron HSM500 are pretty pricey too right?

Yeah I have been looking the MB560 and seen the glowing reviews on here. Will be definitely doing some more research on this in the near future. We kind of like the idea of a small horizontal machine for access to drilling waterlines and side setups bust most of those machines are big $$$ and meant for heavy production so not sure if there's something in the middle ground that would suit our needs.

The whole new machine idea just came up the last few days, and now we are considering 5-axis machines also, the idea of shifting insert work/trickier electrodes to a 5-axis and doing the easier stuff on the current 3-axis makes a lot of sense.

A Willemin-Macodel 308S2 is only a bit smaller work envelope than the HSM200. 38S2

What's your biggest chuck/electrode size? Around ITS50 or bigger stuff?

Those machines look really nice, I remember seeing them come up on here once before, thanks for the reminder. The only thing that could be an issue is it looks like they don't have any presence in Canada? NY state isn't too far but it could be hard to get service up here.

We use 3r stuff but 50mm x 50mm is about the biggest size trode we make on a regular bassis, the vast majority come from .750" and 1" round.
 
Fellow Mikron/HSM machine user, so some bias assumed.. But it is a great little package. I'd probably skip the HSM200 and jump up to the HSM400.

There's a decent argument that any gains from changing MTB would be negated through proliferation of control/process. It's hard to imagine much gains, not much room to improve on the HSM series for this application.
 
Fellow Mikron/HSM machine user, so some bias assumed.. But it is a great little package. I'd probably skip the HSM200 and jump up to the HSM400.

There's a decent argument that any gains from changing MTB would be negated through proliferation of control/process. It's hard to imagine much gains, not much room to improve on the HSM series for this application.

For sure, we really like the HSM500 and are definitely leaning towards another Mikron if we can find the right one. Just need to make sure it's the best choice for us.

We are completely on board with the benefits of standardising controls. It would probably be easier when we want to add some automation as well staying with the GF stuff gives them one less thing to blame when things don't work right ;)
 
I'll second the suggestion to skip the HSM200 for a HSM400. Unless your location is space limited the HSM400 is a better deal. Last time I checked the factory pallet pool was a ridiculously cheap option at ~$30k.
 
Hi Rob007:
I cannot advise you on a good electrode milling machine other than to say if you want to be efficient with your EDM work you really want to go to graphite trodes in spite of their drawbacks.

Graphite is so much better for trodes than copper is; probably the single biggest reason people like you and me shy away from using it is the godawful mess cutting graphite creates and second is the outrageous cuter wear you get unless you use pricey diamond coated cutters.
But if you do anything more than the casual occasional tiny burning that I do, the gains from graphite will so hugely outweigh the drawbacks that there really shouldn't be an argument about which to use.

I'd put my pennies on a trode material switch if you're doing any reasonable amount of burning...get good at knowing what graphite demands on your sinker and leave your old style of burning with copper in the dust sucking wind.
So I'd be bringing that Mikron back into the fold as a graphite machine and get a nice tight 5 axis mill for milling steel.
Between the two, you'll be so far ahead for productivity that you won't recognize your shop anymore...less burning because of the 5 axis and its capabilities, and way faster burning when you just can't mill it.

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining
 
I'll second the suggestion to skip the HSM200 for a HSM400. Unless your location is space limited the HSM400 is a better deal. Last time I checked the factory pallet pool was a ridiculously cheap option at ~$30k.

We have the GF guy coming up next week to go over some options, looking at the published specs we can't figure out what the big difference is in the HSM400 vs. the HSM500?

Other than the availability of a 5-axis model of course, looks like the travels and spindles are the same with the only difference being a pallet receiver table on the HSM400 vs a T-slot table on the HSM500.

Sounds like the pallet pool is a few more dollars up here in Canada but still very reasonable...



Hi Rob007:
I cannot advise you on a good electrode milling machine other than to say if you want to be efficient with your EDM work you really want to go to graphite trodes in spite of their drawbacks.

Graphite is so much better for trodes than copper is; probably the single biggest reason people like you and me shy away from using it is the godawful mess cutting graphite creates and second is the outrageous cuter wear you get unless you use pricey diamond coated cutters.
But if you do anything more than the casual occasional tiny burning that I do, the gains from graphite will so hugely outweigh the drawbacks that there really shouldn't be an argument about which to use.

I'd put my pennies on a trode material switch if you're doing any reasonable amount of burning...get good at knowing what graphite demands on your sinker and leave your old style of burning with copper in the dust sucking wind.
So I'd be bringing that Mikron back into the fold as a graphite machine and get a nice tight 5 axis mill for milling steel.
Between the two, you'll be so far ahead for productivity that you won't recognize your shop anymore...less burning because of the 5 axis and its capabilities, and way faster burning when you just can't mill it.

Cheers

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

That's very interesting. I will admit I'm not much of a moldmaker myself, I'm a transplant from the tool and die world who is just starting to feel like I "get it" when it comes to molds thanks to some of the more experienced toolmakers I'm lucky enough to work with.

The copper vs. graphite material question is something I've questioned before but I've never really found a definitive explanation of the differences. It sounds like speed of burning is the main advantage, but would electrode wear be greater requiring a greater number of electrodes?

We already use diamond cutters on the copper electrodes and love them. I've got almost 400 hours on a 2mmx10mm loc Ballnose, at 40,000rpm and 80inches per minute!

I just went and had a chat with out EDM guy, who has worked with graphite before and he feels it could cause us problems machining because of the amount of small/fine detail our electrodes often contain. Not unheard of for us to have ribs .010" thick by the time you add spark gap, and that sort of thing.

Of course toolmakers often have that way of justifying their own personal preferences, maybe he just doesn't want to deal with the mess :scratchchin:


The more we look at things getting a 5-axis machine does seem like a better and better idea. It would help for the trickier electrodes too. I'm cutting some electrodes this morning with .012" corner rads than go down .375" deep at 6 instances per electrode. Times four electrodes, they should be done in 10 hours or so. Would be soo much easier if I could tilt them and use the corner radius on a bullnose endmill :nopity:
 
Hi again 007Rob:
The main issue with using copper vs using graphite for trodes is that copper cannot take much power compared to graphite.
Copper melts at a much lower temperature than the sublimation temperature of graphite and graphite wears far more slowly at typical burn rates.
So burning with copper will always be slower than burning with graphite except within a narrow window of power settings and cavity geometries.
Copper will also typically need more electrodes to burn to print because of the higher wear factor.

A second issue that often gets overlooked, is the incredible tendency of copper to leave big honker burrs when you cut it, so to clean those up perfectly takes time and I've found the increased trode prep time to be substantial.
As I'm sure you know by now, leaving burrs on a copper trode can give you fits when the whole burn stalls because of a tiny little hanger in the corner shorting the job and driving you batty until it's found and removed.

To be fair, there are advantages to copper and they are useful ones.
Your fellow toolmaker is correct; highly detailed burns can benefit from the finer finishes that can be obtained with copper or copper tungsten.
Fragile electrodes will have less of a tendency to lose a bit of trode and have it rattling around in the burn making Holy Hell in your cavity.



Some features are FAR easier to process in copper; wire EDM cut electrodes are a doddle in copper and can be a hair-tearer in graphite.

But as a general rule, the principle holds; graphite overall will cut a good quarter to third off your overall EDM processing time compared to copper.
If you are willing to pony up for POCO Angstrofine graphite for your most critical burns you'll find it's as good or better than copper for fussy detail burns too, but it's pricey stuff.

And then there's the mess!!
Nothing quite like coming home after a day's work and blowing a ton of black crap out your nose holes while visualizing what the insides of your lungs must look like, never mind the insides of all your computers and machine slides and.....

Be aware though, even after all this lecturing I've just done about the benefits of graphite, I run Telco copper.
I just can't face the mess of graphite.
However, my EDM work is not a profit center for me; I still build the odd mold here and there but not even remotely full time; so if I'm inefficient so what!!
My little sinker burbles away in the corner while I do other things and I rarely ever face a time crunch because of it.

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining
 
Hi again 007Rob:
The main issue with using copper vs using graphite for trodes is that copper cannot take much power compared to graphite.
Copper melts at a much lower temperature than the sublimation temperature of graphite and graphite wears far more slowly at typical burn rates.
So burning with copper will always be slower than burning with graphite except within a narrow window of power settings and cavity geometries.
Copper will also typically need more electrodes to burn to print because of the higher wear factor.

A second issue that often gets overlooked, is the incredible tendency of copper to leave big honker burrs when you cut it, so to clean those up perfectly takes time and I've found the increased trode prep time to be substantial.
As I'm sure you know by now, leaving burrs on a copper trode can give you fits when the whole burn stalls because of a tiny little hanger in the corner shorting the job and driving you batty until it's found and removed.

To be fair, there are advantages to copper and they are useful ones.
Your fellow toolmaker is correct; highly detailed burns can benefit from the finer finishes that can be obtained with copper or copper tungsten.
Fragile electrodes will have less of a tendency to lose a bit of trode and have it rattling around in the burn making Holy Hell in your cavity.



Some features are FAR easier to process in copper; wire EDM cut electrodes are a doddle in copper and can be a hair-tearer in graphite.

But as a general rule, the principle holds; graphite overall will cut a good quarter to third off your overall EDM processing time compared to copper.
If you are willing to pony up for POCO Angstrofine graphite for your most critical burns you'll find it's as good or better than copper for fussy detail burns too, but it's pricey stuff.

And then there's the mess!!
Nothing quite like coming home after a day's work and blowing a ton of black crap out your nose holes while visualizing what the insides of your lungs must look like, never mind the insides of all your computers and machine slides and.....

Be aware though, even after all this lecturing I've just done about the benefits of graphite, I run Telco copper.
I just can't face the mess of graphite.
However, my EDM work is not a profit center for me; I still build the odd mold here and there but not even remotely full time; so if I'm inefficient so what!!
My little sinker burbles away in the corner while I do other things and I rarely ever face a time crunch because of it.

Cheers

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

Thanks Marcus. I will consider all of this as we decide how move forward. For sure a 25% or more decrease in burning time would make a noticeable difference when the EDM machines have been running day and night for the past six months!
 
HI again Rob:
Don't forget, if you're used to running copper, you will have to re-learn what makes your machine happiest and most productive as you go to a new trode material.
There will be experiments.
There will be pissing and moaning
There will be screwups and messed up jobs until this gets figured out.

Your best bet, if you have modern equipment that is still supported is to invite the application engineers from the machine tool builder in to help you get your process running as good as it can be made to run before you go hog wild and make the big commitment.
If the gains are not as grand on YOUR gear as I made them out to be, you need to know that before you dive in with both feet, so calling in the tech boys for consultation would be my first step.
Show them what you do and let them tune your process on your gear with your trodes and your workpieces.
Make up some simple representative trodes (or get Saturn or someone to make them up for you to keep the mess out of your shop) and burn some steel.

There's a lot to learn in order to make this a clean transition.
Above all, cut your guys some slack...all the details of running the new trode material to best advantage need to be learned and that takes experience with the details and sadly, the odd disaster.
Things like what orbit and overburn allowance, how skinny can you go, how close can you go roughing and still clean up finishing, what trode material for when, how much poop to give it roughing, what's your best possible finish, what can you get away with for flushing, etc etc etc.
It's not gonna go brilliantly simply by issuing a directive from above but it will go better in the end if every stakeholder learns it thoroughly.
One nice reassurance though, (if your machines are modern) is that the controls are super intelligent and the settings from the factory are usually pretty good right out of the gate.

Cheers

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

Edit: Here's a link to a shill piece from POCO, but it's not badly written and offers a nice comparison of the two materials, bearing in mind, of course, that POCO wants to sell you lots of graphite!!

http://edmtechman.com/library/EDM-107855-0814 Cooper vs Graphite.pdf

MC
 
As a Roeders user I wouldn't look anywhere else, the accuracy is jaw dropping and I love the control. Although it's their own control and I was a bit wary of it coming from Heidenhain, after a few weeks of getting used to it I would never look back.
 
Hi all. First time to post here. I was really excited to see this topic come up. I've been building molds for over thirty years using graphite for electrodes. Where I work we have a hsm 400 lp with a erowa pallet system. We have pallets set up for 6 position erowa Chuck's for small trodes and pallets with single Chuck's for larger trodes. It is set up this way so we also can hard mill or cut graphite. Simply an awesome machine. We are shortly looking for another machine set up just for graphite to replace 3 bostomatic 12G's . Single station Chuck , feeding electrodes not changing pallets. I've heard great things about the Roeders. Just wondering how big of tool changer and what kind of automation you are using.

Sent from my XT1585 using Tapatalk
 
Hi all. First time to post here. I was really excited to see this topic come up. I've been building molds for over thirty years using graphite for electrodes. Where I work we have a hsm 400 lp with a erowa pallet system. We have pallets set up for 6 position erowa Chuck's for small trodes and pallets with single Chuck's for larger trodes. It is set up this way so we also can hard mill or cut graphite. Simply an awesome machine. We are shortly looking for another machine set up just for graphite to replace 3 bostomatic 12G's . Single station Chuck , feeding electrodes not changing pallets. I've heard great things about the Roeders. Just wondering how big of tool changer and what kind of automation you are using.

Sent from my XT1585 using Tapatalk

Not sure if this is aimed at me but we had the extended 40 position tool changer and the RCE2 robot. with 7 positions for its 148 and 31 positions for ITS 50.
 
Not sure if this is aimed at me but we had the extended 40 position tool changer and the RCE2 robot. with 7 positions for its 148 and 31 positions for ITS 50.
Yes, thanks!! With the hsm 400 lp we have a 60 position tool changer . I think 40 would be fine for our application. On long run sets we can put timers on our tools and have fresh backups . What size of machine are you running, and what size of tool holders. We are currently in the start of a 90 mold package with a lot of burning on each tool. Automation in electrode machining is the key.

Sent from my XT1585 using Tapatalk
 
The machine was the RXP500DS (5X) with the automation but I have also ran the 3x version and RXP801, all were HSK40. The Roeders control works with tool names rather than numbers. so you can have any number of the same tool in the magazine. Then at the end of tool path, you can set the machine to check the out going tool for breakage and wear, if the tool is broken the machine will unload the part and bring in the next part. If the tool is worn you can either have the machine carry on to the next tool path or re-cut that tool path again with a sister tool, the tool will also be automatically measured if there are no length or diameter in the tool data page.
 








 
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