Re: [CAD_CAM_EDM_DRO] orange peel on aluminum

----- Original Message -----
From: Jon Anderson <janders@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Sunday, April 22, 2001 1:20 PM
Subject: Re: [CAD_CAM_EDM_DRO] orange peel on aluminum


> Tom,
>
> Ideally you want both available. Sometimes you need cooling more than
> lubricating, and the water-based are better at that, plus you can get
> more air volume which can help evacuate chips. Case would be some parts
> I machined with a .165 wide slot along the edge of a .350 thick plate,
> 1.4" deep from the edge. The micro-lube did a better job of lubricating,
> but at a mere 20 psi, wasn't clearing the chips well enough. Also, if
> the aluminum got too hot, it would spread apart, opening the slot and
> required a lot of hand labor to squeeze them back in to tolerance.
>
> Regarding orange peel, I just ran into this last night. Had to flycut a
> 3.5 x 11.5 x 5/8 Al plate. Frankly, I had to hang a tool out way too
> far, and sure enough I got orange peel on the finish. This particular
> tool had a small corner radius. While this might generally help the
> finish, it also increases the length of cutting edge engaged with the
> material, which increases cutting forces, which will move a tool hung
> out too far. I put a dead sharp corner on the bit (though at a 45 deg
> angle to the part surface) and ran at 3000rpm and a fairly low feed
> rate. Wonderful finish. BTW, used the SafeTap stick for lube, final pass
> was .002 DOC, wiped the lube stick down the length of the part three
> places.
> Tool corner radius will improve finish only in a rigid setup. If things
> are marginal, sharp is better but you have to slow the feed to keep the
> finished surface smooth.
> And tools must be dead-sharp. I used to think I was pretty good at hand
> honing tools until I looked at one under a microscope. Yikes!
> I coughed up the bucks recently for a Baldor carbide grinder and it's
> one of the best investments in my shop. Lacking this, one would do well
> to consider making something along the lines of one of the knife
> sharpeners that holds the blade/stone at a fixed angle. All it takes is
> ONE slightly off pass with a hone, and you've ruined the edge for really
> fine work.
>
> Jon A.
>
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