Making a Part Advise on EDM Needed

Hello, We have been trying to help the OP on the other thread in Abrasive Forum. A couple of us think EDM maybe the way to go.
https://www.practicalmachinist.com/...ng-surface-grinder-wheel-small-radius-353473/ Thanks

Richard King said:

Hello, We have been trying to help the OP on the other thread in Abrasive Forum. A couple of us think EDM maybe the way to go.
https://www.practicalmachinist.com/...ng-surface-grinder-wheel-small-radius-353473/ Thanks

Click to expand...

I think I would fixture it up and use an endmill with a very minor radius on it for the 90Deg part at least. The grinding wheel will break down quickly with such a minor size radius on it. If you EDM it you would have to use a .001" wire to get that small a radius. A .001" wire makes basically a .003" radius. I am not that much of an expert on EDM, as I use mostly .008" wire to do .010" wide slots in SS, but I don't even know if there is .001" wire.

Good luck either way.

Mike

.004" wire would work. That would give a .002" radius. The trick is holding such a small part. Sink EDM may be the way to go.

machineit2 said:

I think I would fixture it up and use an endmill with a very minor radius on it for the 90Deg part at least. The grinding wheel will break down quickly with such a minor size radius on it. If you EDM it you would have to use a .001" wire to get that small a radius. A .001" wire makes basically a .003" radius. I am not that much of an expert on EDM, as I use mostly .008" wire to do .010" wide slots in SS, but I don't even know if there is .001" wire.

Good luck either way.

Mike

Click to expand...

I should have said .0015" radius in mine. And Shanes would be be .003" not .002". Remember you have a thou on either side of the wire. A .008" wire makes a .010" slot in most machines.

You might also want to check with the customer and see if that radius is actually necessary or if it is just there to insure that area does not have a larger radius. Many places use endmills that have a radius on the ends making them lest prone to chipping on the flutes.

Sinking would work, I would start with a pc somewhere around 6" long, sink the required grove, than wire that pc every 3/8" into your individual pcs.. rather than sink 50 small pcs.

Richard,

I would recommend doing this on a Wire EDM, as it will be a faster and more repeatable process. You can use 0.004" wire to achieve the smaller than 0.003" radius. You can also look at using 0.002" or 0.003" wire and achieve a smaller inside corner radii, but the level of difficulty jumps up significantly. Using 0.004" will not be an issue on modern Wire EDM machines if properly maintained. I do not know what your Surface Finish requirement is for the part, but I would recommend performing a 2 or 3 Pass Process to make sure you achieve your geometry radii size target.

The issue I see performing this via Sinker EDM is the need to use multiple electrodes to ensure the radii requirement, as the electrode will break down on a sharp corner detail. Sinker EDM will also require that a fine finish is produced on the part to meet the geometry radii requirements, making the cycle time longer. The electrodes will also need to be redressed and re-machined for each part to ensure consistent quality, so it is the longer cycle time and electrode manufacturing requirements that make Sinker EDM less attractive.

I hope this is helpful!

-Brian