Cleaning Aluminum

[Arc Burn]

I'm welding on a aluminum dump trailer and having a awfull time getting some areas clean enough to weld.I wondered if you can use a spot sand blaster and if so what media would you use?There has to be a way to get into these tight spots to clean better?I can lay a killer bead on clean aluminum(like everyone else )but once you try it in a dirty tight spot you now have a mess to try and grind out etc. etc,,anyways,just wondering?

[Ed Heimbach]

Walnut shells work well with aluminum.
Possibility of silica contamination using traditional blast media.

[Bob]

There are some chemical Al cleaners out there, but I have never had much luck with them. I think Ed has a better approch, "sand" blasting with an unconventional medium. Probably makes a difference what the contamination is ... paint, tar, oxidation, etc.
Bob

[Arc Burn]

It's mostly heavy oxidation.I have done tons of sandblasting with Black Beauty and while i have heard of walnut shells i've never seen them,were should i look?Thanks

[Ed in Ga]

Arc Burn,
I've bought walnut shells for blasting from Northern Tool. Local place only has 1 gal buckets. Use it for alloy heads on motorcycles.
Ed

[Guest]

If ya don't have the luxury of a bead blaster, use a carbide burr, or rotary file, on a drill or high speed air motor.

There's nothin' more frustratin' than a contaminated weld joint.

[lranch]

I'm with Ed, try the blasting if practical. One cheat I have used with mixed results is to get the Al's attention by running the torch across the area without welding it. The high heat will zap most crud and a small wire brush will sweep off the ash. Of couse, this will not work with mig gun, however a Map or Propane torch will losen better than just brush. Hope this helps.

[Roger]

You can buy stainless steel wire brush that will fit die grinder, drills or use carbide burrs.

I'm using electric die grinder at home. Have used lots of noisy air tools but if they have a rear exhaust you can inslall sintered metal diffuser that will muffle exhaust noise. I have installed exhaust hose to keep oily air away from work with muffler on end. The only noise from that tool was bearing noise. Less noise than my electric die grinder.

[Franz]

The makers of Black Beauty also offer Walnut Shell media for blasting.
www.reade.com will get you to their site with plenty of information to digest.

[Arc Burn]

Thanks for the help fellas.

[craig]

i too have tried the chem cleaners. weld-o to be exact. hate the stuff, doesn't do ****. if i'm in a hurry, i hit it with a 4 1/2" angle grinder. even a used disc will clean it up some. may still have pepper flakes on it but at least you'll get penetration. i swear i'm not welding anything but brand new shiny aluminum anymore!

[Ed Heimbach]

Craig, you'll be suprised how soon you forget about your vow never to weld on old aluminum when a trucker shows up at your shop with a fist full of $100's in his hand, telling you that the tailgate,(or sideboard,or the bottom) needs to be fixed yesterday, if not sooner!

[Arc Burn]

LOL Ed!,thats kinda the position i'm in now since i started offering Aluminum,the calls won't stop but most of it is pretty dirty.

[TheOldDude]

Arc,

Wait till you get one with a big old split and still a half a load of
asphalt. You will earn that fist full of $100

But Rocky's approach was the best for me. It takes time but worth it in the long run.

[Arc Burn]

Question-For cleaning in general(any old spot)could you use a aluminum oxide flap disc?have you seen these?are they just gonna make things worse?