Graphite machining/grinding

[chad fisher]

Hey folks, need some help on graphite. We are about to buy a EDM sinker and we are going to move it and a wire edm into a enclosed room of about 20 x 16 with a surface grinder. My question is can you run coolant on graphite if you grind it or does it still get in to the air, should i remove the grinder from the room? Also on machining of graphite what is the best grade to get and how does coolant react while machining and what effects does it have on the machining centers? Most of the time we will try to use

copper for making our electrodes. I have never ran a sinker nor do i have experience with graphite so if any of you can give me any pointers i would greatly appreciate it.

Thanks in advance, Chad

[mold100]

Chad I could go on for hours with you and this topic,NO never use coolant on graphite,If you use a descent graphite you shouldnt even need to think about using copper If you are worried about the dust carbon makes hook up a sucker system,even if its only a shop vac.Graphite is very abrasive so if it gets in the ways of a machinig center the LONG term effect probably isnt good but what I have found worse is graphite is HIGHLY conductive so if it can find a way to controller or computer boards it will,

there are thousands of graphite manufacturers alot of people say only POCO,screw that its way overpriced but it is good,start with a company in rochester N.Y. M.W.i corp,great service and cost.Every application has a differant use.Their EC-15 is an o.k. large cavity graphite then EC-16 is better and so on.These grades can be purchased copper impregnated but I only use that where thermal conductivity is real high like in Beryllium.you want to definetly keep graphite out and away from your coolant,not only does it make it dirty and grity,it will change its chemical properties again use a shop vac or sucker system.Like I said I can ramble for hours if you have something specific e-mail me.

 

[ 10-17-2002, 12:29 PM: Message edited by: mold100 ]

[Tony]

Back in 93' friends at work called me

"Crazy Sambo" I did only Carbon Mfg.

 

Can you run coolant on graphite?

Yes but then you have to "Bake them " to get them dried out. (Not worth the hassle)

 

What is the best grade to get ?

We use AR-8 carbon mostly.

We Get all are Carbon Ground to are shops Standard fixture sizes. Like .250 x1.500 x3.000

etc. From Ohio Carbon Blank 800-448-8887

Avoid the hassle of Whacked out Carbon sizes

From human error,Buy it To size.(Is Cheap)!

 

I go Copper impregnated when the Electrode is really tall and thin as in Fragile .

The copper in it Makes it Stronger or

Use it for Better wear resistance like

If you are burning someone's Logo that has

A lot of small Crisp detail.

 

You also have to change your EDM machines

Power settings to "Copper"

When you burn with Carbide you change the settings to "Carbide"

Or it wont burn very well,and you will be wondering what is going on?

 

I have shorted out Two spindle motors

over the years because the dust would rain down on them and collect. one day you hit cycle start

And you hear a CRACK!And lightning comes out of the top of the Machine (Dude....,Awesome)....!

 

Use any Paper/Cartridge style filtration.

Even a Large Shop vac.I was using a "Bag" style

Collector.They are for grinding grit not 1/2 micron dust that carbon is. The finest carbon dust will get past the cloth in those style collectors.

 

Carbon Will pack and Grind when trapped in holes etc.So you will have to lightly blow it out of the holes while machining it too.

One nice thing you can Plunge right into it

with reckless abandon ,No entry hassles.

 

I have a VMC dedicated to Carbon.

I do not want it in my other machines coolant ever.It tears up all the seals.

Good Luck

Tony

 

[ 10-17-2002, 04:33 PM: Message edited by: Tony ]

[Guy Arseneault]

Hi Chad,

 

I agree with Mold100 and Tony. We use a vacuum system on our grinders and shop vacs at the milling machines. We also have a Bostomatic for high feed and high speed milling of graphite only. We use Graphel 3800 series mostly.

 

Have plenty of soap around to wash hands, it is very dirty and messy shi*.

 

Guy

[chad fisher]

This is getting pretty interesting! These are the things the tool salesmen neglect to tell you.

We plan to get the machine and i am pleased with the responses i am getting. If by chance you all have some more "do's and don'ts" i would really like to hear them. Thanks so far!

[Kevangel]

I use a 20 gal. shop vac. for carbon.Works great,BUT use special bags rated for fine dust(like drywall dust) and I also ordered the fine dust cloth pre-filter (circular, $15 dollars-ordered from factory form inside box for accesories).Have a total of 3 filters inside cannister.Every so often I shut vac off and bang it against floor to knock dust off filters(will get many more miles this way). Cheaper carbon material machines easier and sometimes burns faster(I think).

[Brian @ MWI]

Mold100 & Chad, Thanks for the ad!! At MWI, all we do is graphite. All answers above are correct. We do carry a wide variety of grades specifically for EDM; different grades for different applications (i.e. roughing, detail, finish, etc.) Let us know what you're doing. You can contact us at (800) 966 4694 or 585 424 4200. I am in charge of the machine shop here and would be glad to give you advice. I would add to the already-posted comments: coolant is not necessary, use a proper vacuum device. Don't forget, however, that graphite dust is very fine and conductive and will quickly ruin a normal 'shop vac' type motor and/or control cabinet on a CNC machine if not properly ventilated. I'll have one of our sales people call you to inquire about your application. In the meantime, if you have any machining questions, let me know....

[rottncf]

Ditto on the Carbon-only machines--saves much hassle and cleaning time.

A good vacuum system is an absolute must--I used a 5-gallon shop vac and made a custom large mouth intake plenum rather cheaply with some parts from Home Depot--works great.

I also use a low pressure air stream directed across the electrode being machined into the vacuum suction--this helps with tool wear as it will keep the graphite from building up in pockets around the electrode.

Sometimes if I have problems with chipping(sharp features) I will brush a little dialectric on the electrode, and this too can help.

Coolant--NO WAY--It just makes a disgusting mess. The worst coolant stench I've dealt with is graphite contaminated YUCK!!! Although I have seen some graphite coolant systems, it just doesn't seem worth the trouble.

Graphite mfg is a whole different ball of, well, carbon.

 

Les

[crazy^millman]

14 hours ago, sedmondson said:

Would you please give me some ideas on the best wheels for grinding graphite electordes. Thnks

20 year old thread? I have not seen any of these folks on the forum in a long time.

[Fred @ Slate Industries]

120 G was the wheel back then.

Nobody makes them now 

It was a fine grade soft wheel

A 46 is soft but coarse your going to get " clingers" or loose grit bouncing around in the wheel edge leaving a series of dotted lines on your carbon...

They can be removed by lightly pressing wood up against the wheel .

I'm still here but mainly check the obituary thread to see if I'm actually dead and this is actually a dream or something.

 

MERRY CHRISTMAS 

Old Forum Cheers !

[#Rekd™]

8 hours ago, Fred @ Slate Industries said:

I'm still here but mainly check the obituary thread to see if I'm actually dead and this is actually a dream or something.

Great plan of action Tony!!!!!