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What to look for when buying a small hole EDM drilling machine

Mazak Man

Plastic
Joined
Mar 28, 2013
Location
Masontown,P.A.
We are currently in the market for a used small hole EDM. We have a particular job that it is being purchased for.
The machine will be used to drill a .0925 hole 3/8 thru +.002 -.000 the material will be 440c 55rc.
From what I've read I don't need a high voltage machine (under 35 volts)
Does anyone have anyone have any other suggestion on what to look for brands to buy not to buy etc.
I don't need a big table the parts are small.

Any help or suggestions would be greatly appreciated.
 
My experience, you won't hold .002 tolerance consistently. The electrode will be tapered as it is being used, and the guide and electrode needs clearance which will cause some run out. I think you will be lucky to get +/- .003". YMMV.
 
Hi Mazak Man:
If you need a hole of this precision you have two paths forward with EDM.
One is to get a machine that is designed for precision small holemaking.
Makino makes a few models marketed specifically for this application and they can make a hole within tenths.
The second way if it's a through hole, is to hole pop the hole undersized and then wire EDM it out to final size and location.
This will also give you a hole within tenths if you want it.

Other ways not involving EDM are to mill it or drill and bore it.

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining
 
Marcus,
Do the Makino precision EDM drills orbit to maintain size? Or change electrodes? Hard to imagine how they could do it with conventional hole popping technique.

Mike,
Drilling hardened 55R/C material?
 
Hi RJT:
When I last looked (years ago), the Makino precision hole drillers were just a high precision sinker with a high speed C axis and an attachment for wire EDM cutting a spinning silver tungsten electrode to make it perfectly concentric and to whatever size you wanted.
So the trode blank was mounted in a collet, the trode was wire EDM dressed while spinning, and then it was positioned and used.
So far as I know, there was no hole popping technology used, I believe it was standard sinker technology, with some generator mods to allow ultra low power burns.
They made super claims for it when I looked way back when...they were apparently the only ones who could EDM drill holes less than 0.004" diameter to within a micron, but the trode was solid, so no through flushing and no hole popper speeds.
I know they were supposed to be quite a bit better than Sarix who was the other small hole EDM contender of the time.

It looks from the new offerings on their website, that they now offer small hole drilling with a more typical hole popper setup but using dielectric oil rather than water and a hollow trode.
I can't find any references to the old tech they showed way back when ...maybe they've rendered it obsolete with their newer offerings.
Brian Pfluger would be the one to set the record straight...I'm going from memory and I want to say it's from a decade ago.
I did have great machine lust for one, but could never justify the price.

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining
 
After talking to the person that does the the final product assembly and looking at a sample part someone else did. We have more tolerance than I thought (more like plus .004.)So my next question is anyone familiar with Elenix brand small hole machines?
 
Mazak Man,

Makino does offer a special high accuracy EDM Drill machine that is integrated into our high-end EDAF-Series Sinker EDMs, and we call this package Fine Hole EDMing. These EDAF-Fine Hole machines provide a wide range of capability in that they can perform standard 4-Axis Sinker EDM work as well as high precision EDM Hole Drilling. There are many unique items and technologies on Fine Hole machines that are dedicated to EDM Drilling, such as the removable Fine Hole Guide Arm, Electrode Tool Holders, the high-speed rotation C-Axis, and the 10MPa (1,500psi) high pressure pump for thru-electrode flushing.

The Fine Hole machines utilize tube or multi-channel electrodes for machining of holes just like other EDM Drill machines. Tube electrodes are generally available down to 0.004” diameter, and Makino can automatically Tool Change electrodes down to this size. For hole sizes under 0.004”, a solid rob can be used, or the machine is able to discharge dress a solid rod to whatever size is needed, and we’ve produced holes down to 0.0004” diameter before. A key feature of the Fine Hole machines for EDM Drilling is that all machining is performed fully submerged in di-electric oil, as this helps improve machining stability and enhances accuracy due to the finer control over the discharge energy. The EDAF2 or EDAF3 machines can be equipped with the Fine Hole configuration, and the generator being a full-blown Sinker EDM machine brings more technology and capability (more tools in the Toolbox) to EDM Drilling applications, which allows the ability to orbit and size holes if needed (depends on L to D ratio).

I believe you are in Western PA, and if this is correct, you can reach out to Progressive Tool & Die in Meadville, as they recently purchased an EDAF2 Fine Hole machine. Please let me know if you have any questions.

Here is a link to a Makino Webinar that discusses the differences between traditional water-based EDM Drilling and the oil-based Fine Hole process.

Oil vs. Water EDM Drilling Webinar: EDM Hole drilling. Oil versus Water | Makino

- Brian
 








 
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