machining graphite

[dang]

I've settled on using Diamond Coated End Mills. Even though they're QUITE EXPENSIVE, I've read accounts that state that 4, maybe 5 Graphite projects can be eaked out of diamond end mills. This is where POSSIBLY only 1 out of conventional end mills, maybe not even that.

Here I thought that Graphite would be easy to machine. Like butter. It's tougher than I thought. Guess I was wrong. At least I'm accustomed to it.


Worse than that, I found like 400 lbs of EDM Graphite for FREE on Craigslist! By the time I called it was all gone. Oooooooh the agony.

Where dust is concerned, I'm thinking of building an enclosure. I'll pump coolant in to catch the dust as it emerges from behind the cutting tool. I've seen accounts of this working as well.

Thanks for all the input.

My new question is whether or not I can cut Graphite on a CNC'd Sieg X2 Mill. The mill runs under 4000 rpm's. I don't know if that'll be an issue or not.
I do know that if it is possible, that it would kick serious butt!

[K&Y]

I've settled on using Diamond Coated End Mills. Even though they're QUITE EXPENSIVE, I've read accounts that state that 4, maybe 5 Graphite projects can be eaked out of diamond end mills. This is where POSSIBLY only 1 out of conventional end mills, maybe not even that.

Here I thought that Graphite would be easy to machine. Like butter. It's tougher than I thought. Guess I was wrong. At least I'm accustomed to it.


Worse than that, I found like 400 lbs of EDM Graphite for FREE on Craigslist! By the time I called it was all gone. Oooooooh the agony.

Where dust is concerned, I'm thinking of building an enclosure. I'll pump coolant in to catch the dust as it emerges from behind the cutting tool. I've seen accounts of this working as well.

Thanks for all the input.

My new question is whether or not I can cut Graphite on a CNC'd Sieg X2 Mill. The mill runs under 4000 rpm's. I don't know if that'll be an issue or not.
I do know that if it is possible, that it would kick serious butt!

Yep. diamond coated endmills will give you longer life, most definitely, but with the PCD alternative, you can re-lap the diamond when it's cutting edge has worn out, thus increasing tool life even further. I didn't know if you had a speed/feed rate chart to use as a reference, but I thought I'd post one up for you as per PCD usage. Hopefully, this will help.

[svenakela]

Here I thought that Graphite would be easy to machine. Like butter. It's tougher than I thought. Guess I was wrong. At least I'm accustomed to it.

It is easy to cut, but it will make the tools dull very fast.

[dang]

It is easy to cut, but it will make the tools dull very fast.

Thanks for clearing that up for me.

[rakker16mm]

At the risk of bumping an old thread... I am machining some graphite for a rocket by Team Phoenicia

[nomedia="http://www.youtube.com/watch?v=h7U20yCmgjw&feature=player_embedded"]YouTube - Engine for the Zephyr Aurora[/nomedia]

About 30 years ago at my first paying job as a machinist I had to cut graphite. The dust was awful and I had black goobers in my nose for the entire job run. My boss was this crotchety old guy from Czechoslovakia, a great machinist but not too big on the idea of dust masks or even safety glasses. I didn't stay long...

Anyway this time around I thought I would do things my way. I am using a wet/dry shopvac pulling through a water trap. Really it is a glorified hooka and it is very effective. Nearly all the dust is sitting at the bottom of the bucket as black sludge.

[awemawson]

I was suprised to see in an earlier post in this thread about the graphite dust being very abrasive. Powdered graphite is used as a lubricant so I wouldn't have expected that to be a problem - anyone know for sure as I will be machining EDM electrodes in the new year on my Beaver Partsmaster for use on my die sinker?

AWEM

[svenakela]

I was suprised to see in an earlier post in this thread about the graphite dust being very abrasive. Powdered graphite is used as a lubricant so I wouldn't have expected that to be a problem - anyone know for sure as I will be machining EDM electrodes in the new year on my Beaver Partsmaster for use on my die sinker?

AWEM

Read the thread again, there are several people with the knowledge that posted info about what you are asking for. That's the main reason for using high end mills.

Just because there is a lubricant powder made of graphite it doesn't destroy your end mill? Wrong assumption my friend.

[awemawson]

Not bothered about the end mill - they are expendable - it's the machine slides etc that I'm more concerned about.

There is a world of a differance between carbon and graphite despite them being chemically the same - after all diamond it carbon as well. Carbon used for the electrodes of a battery is usually very hard and brittle, wheras carbon brushes on motors are usually soft. It's that later form I use for EDM electrodes.

AWEM

[svenakela]

You should evacuate or catch the dust in any case, so the guides aren't a problem.

[packrat]

The graphite used in edm is a byproduct of oil refining. The graphite for lubricating is the mineral graphite. Two completely different things with the same name.

When I ran a edm most of our electrodes were form ground on a surface grinder. We would have a set-up electrode to get the correct dimension on, then take the rest of the electrodes to size with one cut each. Talk about dust

[rakker16mm]

The graphite used in edm is a byproduct of oil refining. The graphite for lubricating is the mineral graphite. Two completely different things with the same name.

When I ran a edm most of our electrodes were form ground on a surface grinder. We would have a set-up electrode to get the correct dimension on, then take the rest of the electrodes to size with one cut each. Talk about dust

I can smell the oil after the cut. Fortunately the water trap works wonders for keeping the dust under control and I don't have a black nose. It gets nearly all the dust expect for the lager bits which escape the vacuum. I still need find a way to cover the ways on the lather though.

[awerby]

is that the dust conducts electricty. It's used to make motor brushes and conductive paint, among other things. So if you let it float around your shop, it will get into your computer, with results you may not be happy about...

Andrew Werby
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