Copper Vs Carbon

[JIMMY]

Does anyone machine copper instead of carbon? My general manager wants my to look into it. Any information would be appreciated.

[widgitmaster]

Must be an EDM type question!

Copper is easy machining just like carbon is!

[JIMMY]

What about cutting time. I have cut a lot of copper before but I think it will take alot longer to cut copper than carbon.

[dannystooblue]

Your tooling and machine will make all the differnce in the world as far as time goes. If you have a solid machine with good tooling then you should do pretty well. Copper will not machine as fast as carbon for a couple reasons, number one getting the chip out is not as fast as carbon as carbon turns to dust as it is fractured off, the other is the attention to the stock where carbon is more forgiving when you slam a cutter in to it the copper won't be nearly as friendly. We don't use copper much, it seems like lead times on larger pieces of copper were really long.

Are you trying to get a better finish in the burn, is this the reason for the copper electrode, or is it to reduce the number of electrodes to be machined? If it is for the total number of electroded machined, remember that the more overburn you use, the less wear on the electrode. You might concider making a rougher with more overburn on it and a finisher to clean it up. If it is for finish, remember that the finish on the electrode will be transfered in to the part, so the electrode will have to be polished pretty well as well as a tighter step in your surfacing which may eat up more time in the carbon machine. When it comes to over all time we have had really good luch with carbon, when it comes to finish, copper is needed for extremely good finishes as well as alot more time for the edm orbiting.

Do you use diamond coated tooling to cut your carbon? Do you have a high speed mill as well? Is it one that is suited to machining copper as well? They do not like to machine copper in our carbon machine.
Danny

[Garypl]

Using copper for electrodes is still popular in europe and can have it's place here. the three reasons that I still consider using copper could be.
(1) For extremely small spark side gap (SG) situations. Areas that have no or very small draft and less than .001 SG.
(2) Very narrow slots. graphite can beo too fragile for some situations when features are .005 or less thick and 3/8 or more deep.
(3) fine finishes. with machines capable of 4 micron finishes or better copper is still the king.

I still follow the belief that copper is not better because of using fewer trodes. they take longer to machine, (some times deburr and polish) and much longer to burn with. Unless the shape is simple like a logo or trade mark.

Graphite electodes have the upper hand because of speed (in machinning and edm time) and selection of types of graphite. We can use extremely small grain structure for small gap fine detail situations Poco has a great selection for this, I believe it is called AF series or Poco 4x.
we have large grain sturcture for high amp burning like poco 1.

With poco 3 being a great average grade.

if you still want to use copper get a low sulphur type, I do not have a name but if you are interested I can supply that too.

Usually the reason that I have heard for using copper is because of the way the EDM is being used. a person with good EDM knoledge only uses copper in certain situations. we have high amperage high off time cycles that are incrediable for buring fine narrow and deep extremely fast. use that type of process play amperage you can exceed 50 ampes per in in graphite, wear trodes bur burn really fast.
I really believe that everyone should try a lots of out of the box things and coppper is there. there is also copper impregnated graphite and depending on the type of generator this is decent for reducing wear and limiting the number of trodes.
Gary

[Cruiser]

I have done some copper electrodes in the past in lathe, The primary is to use the most open positive insert possible ! lots of room for the chip to flow then you can rough taking a major depth with hard feed and chip will flow off and pop ! if you push it too tight it will pile up and blow the end off of the tool. And as for pollishing, i used 220 then follow up with good ole brass-o, then it'll shine better than a new penny, and be worth a hole lot more. in the mills they used the same basic principal, lots of possitive !

[Megraster]

Originally Posted by JIMMY Does anyone machine copper instead of carbon? My general manager wants my to look into it. Any information would be appreciated.

Are you referring to EDM? The reason I ask is a 2 Fl EM will rip Through Copper. I haven't used the EDM (Wire Burner) yet, but I remember the other guys talking about changing nozzles and solutions.

[PARESH]

Originally Posted by JIMMY Does anyone machine copper instead of carbon? My general manager wants my to look into it. Any information would be appreciated.

Dear sir,

We provide copper master machining services from Mumbai, India. We are supplying Copper Masters to many Tool Rooms in India on sub contract basiS.

Please find some of images done by us...

It will be our pleasure to work with you.

Thanks & Regards

Paresh Panchal

[Nivec]

I have used both. I currently use copper on Mitsubishi sinker EDM's with great success.

I have 10+ years experience with graphite (carbon) and when I started work with my current employer I almost went completely nuts with the long lead times from using copper. Between the longer machining time to cut the trode and the much longer burn times I was pulling my hair out. I pushed to have my employer switch to graphite a while ago and we gave it a try. We first tallied up what it would cost to make the change. There was a heavy cost in machining since we had to buy a dedicated NC instead of sharing the same machine used for cutting steel. And of course there is the need for dust collection and containment. There is also a big, big difference in raw material cost from Graphite to Copper. Copper cost as much as 6 times what a good grade graphite will cost. And the cost of Copper is sky rocketing. There is also the issue of the number of electrodes required to complete a burn and the degree of detail definition. You simply can't beat Copper's wear rate and surface finish! We found that some burns that I could get away with 1 copper trode required 3 graphite trodes.

So with all these issues taken into account we wanted to make sure the difference at the end of the day would make the switch worth it. So we found a shop to cut graphite trodes for us for a couple jobs. I was very pleased with the results and and so was my employer. But my employer also grew very fond of the idea of having some one else cut the graphite trodes and deal with the mess instead of us. So that is what we do now.

All new jobs that require significant EDM time are done with graphite trodes cut by someone else. We currently use a shop in Michigan who does a fabulous job cutting trodes for us at a very reasonable price. Any other job that requires only a few trodes get done in Copper as well as engineering changes to exisiting tooling.

So what's my point? I go home at the end of the day from my clean shop with clean hands!!

[JIMMY]

I want to thank you all for all the information. I will pass it on to my GM.