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Vibratory Deburring and Polishing
Deburring 6061 Aluminum
This is easily done in a vibrating tumbler or even a rotary style. You need some plastic media. I used media from Grainger that was listed as:
Deburring Media, 3/8 Inch Styrene Triangles, 6 Pounds per
Box, For 6A898 and 6A899
This media was recommended to me by a machinist friend largely because it was similar to what he uses (a 1" wedge shaped product from CandMTopline), but it was available in smaller quantities more suited to my small vibrating tumbler:
My vibrating tumbler was intended for polishing brass for reloaders, but they're all pretty much the same...
I only needed one package of the Grainger media to fill the tumbler. My tumbler was intended for polishing brass for reloaders, but they're all pretty much the same. I chose the one I have largely because it was available cheaply on eBay, and because it had interchangeable "buckets" in case I wanted to purchase more of them.
To use the tumbler for deburring aluminum, fill the bucket with media, add water (I filled mine just below the top of the media), just a little bit of liquid dishwashing soap, put the parts in, turn it on, and walk away. I got a good result after about 5 hours. Here are the parts before tumbling:
Lots of sharp edges and tooling marks...
And here they are afterward, along with a bit of the media:
And after the deburr. Note the nice uniform finish. Tooling marks are all but gone...
The smaller the tumbler, the more time will be needed to achieve the desired effect. In this case, I got a nice even finish over all surfaces. It's best if you can get media large enough that it won't even go into any holes, otherwise it tends to get stuck in the holes and is a nuisance.
I did a whole bunch of scrap parts in the one run. This process really does a nice job replacing tooling marks with a satin finish. If there are gouges or other deep impressions, it won't take those out. However, I did surface a piece with a 3/16" endmill and it pretty well got rid of the tooling marks from that.
This was done with aluminum, which is pretty soft. Mild steel takes longer, and there is some question about whether there's any point in even trying with stainless steel.
Some Vibratory Polishing Tests...
I threw some parts I had in the vibe and left them for 4 days with walnut shells impregnated with green rouge. Here is what I got back:
You can see the polish best in the granite reflection of the edges...
On the left is a part straight off the mill, covered with all sorts of tooling marks. Unfortunately, the flash makes it hard to see when looked at face on. It's hard to photograph these finishes!
Next up is the part marked "deburred". It ran overnight with some deburring media until it had a nice satin finish. There is definitely some grain still on it. In fact, I had some parts that had the vibratory deburr and some that didn't. The ones without were shiny with deep scratches left from the tooling marks. I didn't bother photographing them as the satin finish from the deburr looked better to my eye. Lastly, we have 3 parts on the right that got a 4 day polish in the vibe. There is still some grain visible, so I can't truthfully call it a "mirror", although I notice a lot of people want to call any shiny part a "mirror". But, they are quite shiny. You can see the bottom photo they are reflecting the grain of the granite countertop they're sitting on. All in all it is a nicer finish than the deburr. I suspect it would be nice to have had some grade of abrasive in between the deburr and the polish. I'm not sure what that would be, but there's still too much grain after deburr for the polish to get it to a mirror.
I find when polishing I often have the problem of moving to the next finer grade too soon, only to have it do a wonderful job highlighting scratches that should have been taken care of with the coarser grades. In any event, I am reasonably happy with this first time polishing result. It looks like something you'd buy commercially and think nothing of it. Best of all, I literally forgot about it while the vibe did its work.
I need to experiment a bit more on my exact processes, but I really like this approach. The polished parts also picked up a wonderful smooth feel.
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