SANDBLASTING - do you have a final word?

[mcaswell]

I'm about to finish production of our Anodizing training video, and would like to hear from anyone on how they have prepared the part prior to anodizing.
What is your favorite method?
Has bead blasting or sandblasting caused you grief?

If you've been looking for a highly polished finish, how did you remove the buffing compound?

If there is anything else you'd like to see in the video, now is the time to holler!

[rclint]

I don't have a problem with bead blasting, expect a different outcome on color, you can compare the magazine to the pc base and vq trigger I put up in the anodize pictures.

I also have not had a problem getting buffing compound off, spray it down with full strength simple green, in hot tap water, scrub with a brush, then soak in the hot water/mean green for 10 min or so, then rinse clean, leave in clean water for 10 min or so while I'm working on other things.

Tumbling can be a pain, the media loads with buffing compound, even new media will load up and start working in the wrong direction, coating the part instead of cleaning it in as little as 3 runs of fresh media, this will not come off in my normal simple green cleaning method, I have to buff the part back out on a buffer, I think the tumbler actually embeds whatever the media loads up with in the metal itself.

Just some things I have seen while learning.

Clint

[sswee]

For most parts I prefer a polished part due to the candy color look you get after anodizing.

Bead blasting has caused me to have to strip and rerun parts because the surface was to rough from blasting at too high a pressure and showed alum. through the color. Same as a part with too sharp an edge on the corners and the coating not growing on the corners

I have used thinner but normally use a wax and grease remover for liquid paint work to get the buffing compound off. Then wash in a high concentration of dish washing liquid to pass the water break test.

SS

[rclint]

I know this is not part of you question, but here is what I think would sure help on the video.

Where parts are milled out for letters, serial numbers, name brand. We need a good easy way to be able to mask this, maybe with some type of coating that can be applied then wiped off flush the the letters (that are below flush) will not anodize. I done one and it worked, tried another and it failed. This would be a big step for anodizers to customize some of our work, one more notch on the big commercial people.

Am I the only one who has an interest in this ?


Clint

[acidrain]

I have had good luck blasting with medium (not sure of the sieve) glass beads. My cabinet is a small siphon type beadblaster, with about 35lb capacity. The air pressure is regulated to 60psi, and I use a large compressor with in-line filtration. Water and oil contaminants have not been a problem.
I typically blast in a fairly quick back and forth motion at a distance of ~4inches. I blast only aluminum so that the blast medium is not contaminated.
I tried using aluminum oxide, but found the texture much to sharp, and it often left an ugly blotchy pattern in the finish.

For a polished finish, I machine buff with black compound on a Sisal wheel for the cut, then move to brown compound on a spiral sewn cotton wheel for color. I don't take it any further than that, as the ano process has a dulling effect, and polishing to a mirror finish is a waste of time.
Then, to remove the compound, I've found nothing works better than lacquer thinner and a soft brush. The use of clean solvent is critical, and the disposal of old solvent can be a pain. I live in a large city where hazardous wastes can be recycled by homeowners... no questions asked, so that has not been a problem for me (I am thinking of purchacing a recycling still for this purpose).
After lacquer thinner (and rag dry/polish), a quick dunk in SP degeaser removes any residual traces of contaminants, and water break test confirms cleanliness.