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Sinker EDMing Moldmax (beryllium copper)

keurb

Plastic
Joined
Dec 10, 2014
Location
Rockford, MI
I was wondering if anyone has some experience burning moldmax that might have some tips or suggestions to help.

I have burned moldmax a few times but it has taken a really long time and I have had to double or even triple my electrode quantity due to wear.

We have 4 Charmilles sinkers and I will most likely be using the roboform 550 to burn these jobs. I'm not burning any ribs but I am burning a good amount of material.

Does anyone know if Charmilles has specific technology settings to burn this type of alloy? And what type of graphite would be best to use? I have read that Poco C3 (copper impregnated) might be the best choice but it's also very expensive.

Thank you in advance for your help.
 
Hi keurb:
My experience with Moldmax has been about like you are describing and I don't think there are any magic bullets that will turn this stuff from a PITA job into a gravy job.
I had no better success with C3 than with any other premium graphite; even POCO Angstrofine didn't make a noticeable difference other than costing the earth.
I've also tried Telco copper and copper tungsten also with no great magical improvement.

My single biggest gains have been to mill everything I could as close as I could, make an undersized trode I could drop into the mold cavity as close as possible to the bottom and orbit the trode out to present as much surface are as possible so a decent amount of current could go into the job while keeping the burn path short.
I'd just pour the coals to it knowing I was going to wipe out details from wear anyway, and plan to pick them out later
I found also that flushing the snot out of it was a winning strategy, even when it meant more complicated electrodes with flushing channels.
Breaking up the trodes into simple elements that were easy to cut and re-cut helped me to avoid stressing about the wear rate.
No matter what you do though, I feel your pain.
Make sure your boss knows that you can't win on this job; it'll take what it takes and everyone has to accept that.
Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
www.vancouverwireedm.com
Clarus Microtech
 
implmex:

Thank you for the reply. It sounds like you have some experience burning moldmax and this was exactly the type of feedback I was looking for.
I will now feel confident with how to go about this. I will ask my CNC team to cut as much as they possibly can. I will stick with our standard graphite while making it undersized as much as I can and pouring the coals to it while also getting as much flushing to it as possible. I will also let my boss know that their is no easy way around this.

I really appreciate the feedback.

Brian
 
Actually Moldmax can be quite simple to burn. It is definitely a different animal-and can be frustrating to burn initially. I have had great success with burn rates and electrode wear rates with some simple setting adjustments. I actually have had no issues with Mid-Grade Graphite.

Negative Polarity is a MUST, Reduce on time in half throughout your program, and put as much flushing as possible, and blast it in there. Lastly, I also shut the FUZZY off.

I used to do crazy deep rib details with great success and never any issues.

I run Mits Sinkers, but should be the same on yours.
 
Well that does seem like some pretty simple adjustments. I will most definitely try this. I appreciate the feedback.
 
Hi SteveEX30:
That's very interesting; I've never tried negative polarity because I always assumed the electrode wear would be even worse.

So do you find you have to make more trodes than you would normally, or can you get away with 3 trodes in Moldmax where you'd use 3 trodes in steel?
Do you run them all negative polarity or just the roughers?
Is dropping the "ON" time a strategy to improve the dielectric recovery time or is there some other reason why you find it working so well for you?
This is great information: I really appreciate it because I've always looked on burning Moldmax with dread.
I'll definitely try your recommendations next time I have to burn it.

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
www.vancouverwireedm.com
Clarus Microtech
 
Marcus,

I would edit the Epacks, first one would look something like this. I would carry the POL and ON TIME values throughout.

POL -
IP 5.1 (or 4.5 for smaller details)
ON 2.0
OFF 6.0

JU 4
JD 2

I used same program for Rough/Fin. In a normal situation where I would need 2 trodes in Steel, I would definitely cut 3 possibly 4 detail depending. I was honestly never worried about cutting an extra trode because it was a trade for some very stable and what I considered impressive burn times. I had enough confidence in these settings that I would run "lights-out" with the Toolchanger all night with the FUZZY OFF.


Yep, the lower ON TIME was for DI Recovery and Stabilizing the Burn. I agree with you that you can't put too much flushing into it. Unlike steel, I found the more and higher pressure, the better.

Let me know if you find these settings help. Moldmax was something I worked with almost daily years back. Doesn't seem to be as popular as it once was so I don't deal with it as much. But when I do, I pull up the same damn program each time.
 
you are the best, don't even know, that worked awesome...messing with this stuff for a week on a Makino, switched I over to the mitz..
 
On the Charmilles machines they have a tech file for Fine Graphite to Ampcoloy. These use negative polarity and low On-Times. The best electrode material is a copper impregnated material Like Poco EDM C-3 or C-200 based on the detail. These will get less electrode wear and machine about twice as fast as standard graphites. If you have any questions contact Poco's application engineers and they will be glad to help with machine settings for several brands of machines.
 
Thanks for the reply

Mine is Agie Mondo Star, are they the Feedrate and timer speed?
 

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