Bead blasting

[Rally]

Second topic of the day....LOL

I have seen some push back for using media blasting alluminum pieces. Reason given was the heat/pressure caused distortion of the said pieces. I have not personal seen anything heat up during this process. Anybody have any ideas or personal experiences?

Thanks

 

[erj-145mech]

Too much air pressure, too large media, too long exposure will distort and stretch thin aluminum pieces. Also, if the pieces are alclad, it will strip it off.

Stripped a couple of airplanes using baking soda blast, and it worked well. We alodined the pieces right afterwards too in order to give some corrosion protection.

 

[Rally]

Excuse my ignorance but I am just trying to learn. What is alclad? Its any anti corrosion in the manufacturing process right? What exactly is it and how does it compare to alodine? I have done acid etch and alodine before and I know acid etch is used to remove corrison and treat the metal for the alodine application. Alodine is a goldish corrison protectant right?

 

[TrafficInSight]

Excuse my ignorance but I am just trying to learn. What is alclad? Its any anti corrosion in the manufacturing process right? What exactly is it and how does it compare to alodine? I have done acid etch and alodine before and I know acid etch is used to remove corrison and treat the metal for the alodine application. Alodine is a goldish corrison protectant right?

Alclad refers to an aluminum alloy with a pure aluminum "clad" surface.

 

[GravityHater]

http://www.airweb.faa.gov/Regulator...86256B4500596C4E?OpenDocument&Highlight=43.13
chapter 6, see 6-12 for some of these answers

I found this:
Alodyne -- a chromic acid conversion process that leaves a corrosion
resistant film on aluminum surfaces.

Alclad -- Alclad is a trademarked process.
Berylium copper aluminum
alloys provide very high strength. These are the 2000 series
alloys like 2024 which are usually used for aircraft. These
alloys have a problem because of the copper in suspension in
the aluminum there are granular boundaries between copper and
aluminum that are rather far apart on the electro scale. In
the presense of an electrolyte, like dirty water, they make a
small battery and one of the poles becomes sacrificial and
corrodes away. This intergranular corrosion is a serious
problem with these alloys. However, pure aluminum will corrode,
but when it does it forms an aluminum oxide coating that serves
as an excellent corrosion barrier.
Someone got the bright idea of coating both sides of the sheet
of aluminum with a thin layer of pure aluminum. There is a
layer about .001 inches thick of pure aluminum on each side of
the sheet.

 

[wooferdog]

Excuse my ignorance but I am just trying to learn. What is alclad? Its any anti corrosion in the manufacturing process right? What exactly is it and how does it compare to alodine? I have done acid etch and alodine before and I know acid etch is used to remove corrison and treat the metal for the alodine application. Alodine is a goldish corrison protectant right?

Rally-
Depending upon the blast media, beadblasting will remove material in a hurry, and, yes, affect material strength. And as another poster said, baking soda blast works very, very good.

The purpose of acid etch is not to remove corrosion, but to create a suitable (read: best) surface for the application of the next layer--be it primer, or alodine.

If you are looking for info on bead blast, or baking soda blast, look at www.grainger.com

For info on alodine, www.aircraftspruce.com

-WooferDog

 

[Rally]

Will Soda blast work in any blasting machine? I have a large bead blasting cabinet.

 

[DieselDragRacer]

Will Soda blast work in any blasting machine? I have a large bead blasting cabinet.

No! It an entirely different and expensive setup.

My dad and I make our own automotive primers, bases, single stages and clears and a nationwide problem right now with the growth of the automotive rustoration market is morons operating mobile soda blast trailers. The soda blasting process itself is an excellent way to strip metal and aluminum IF the process of neutralizing the surface post-soda blasting is understood and followed. Unfortunately it is not and many blasting operators are clueless therefore we along with the major paint companies are telling the automotive aftermarket we won't stand behind our products being applied over a soda blasted surface because there is too much misinformation on the neutralization of the surface.

If you have someone soda blast a plane for you be sure you have proper written instructions that you follow to the letter to follow for your own insurance! Like I said it's a great stripping process IF the surface is neutralized correctly.

I've painted enough bugsmashers to know I sure as hell would not want to have to strip one down to the AL and start over because the surface was improperly neutralized or prepped for any reason.

 

[9GClub]

Clad aluminum looks pretty, but keep in mind that it's slightly weaker than an unclad sheet-- and once you scratch through the 1100 on the surface-- or polish it away, ding it, or otherwise compromise it-- you're essentially back to square one with respect to corrosion. Also, note that it's not clad on the edges, so butt joints or even lap joints are gonna be hotspots for problems unless they're protected.

Bead blasting is also great in theory and in some practical applications, but as the others mentioned and as you know, it requires a rather elaborate setup, plus it'll damage thin metal pretty quickly. You're probably better off just using paint stripper (on metal).

Just my $0.02.

 

[wooferdog]

No! It an entirely different and expensive setup.

My dad and I make our own automotive primers, bases, single stages and clears and a nationwide problem right now with the growth of the automotive rustoration market is morons operating mobile soda blast trailers. The soda blasting process itself is an excellent way to strip metal and aluminum IF the process of neutralizing the surface post-soda blasting is understood and followed. Unfortunately it is not and many blasting operators are clueless therefore we along with the major paint companies are telling the automotive aftermarket we won't stand behind our products being applied over a soda blasted surface because there is too much misinformation on the neutralization of the surface.

If you have someone soda blast a plane for you be sure you have proper written instructions that you follow to the letter to follow for your own insurance! Like I said it's a great stripping process IF the surface is neutralized correctly.

I've painted enough bugsmashers to know I sure as hell would not want to have to strip one down to the AL and start over because the surface was improperly neutralized or prepped for any reason.

DDR: Give us a brief description of how the surface is neutralized and prepped after soda-blasting.