yesterday i was making some skid plates at work with some aluminum sheeting and could not get them clean to save my life. welds were shitting all over.
i lightly sanded them and brake cleaned them where i was welding the brackets on, i also tried acetone after the brake clean didnt work.

that is the same process i use for all aluminum, and so for it has worked great.



any ideas as to what i should try??




if it matters the welder is a miller dynasty 200dx. 3/32 2% tungsten, 150amps, 190 freq, tried from 40-75balance

 

don't forget to turn the gas on

 

i have forgotten a couple times but not this time. i even turned it up to 35 to see what ahppened, no dice

 

I always use Simple Green and an abrassive pad then rinse with water. try that and see if theres a difference. it works for me

 

use a grinder then hit it with acetone.
You must weld immediately after cleaning as the protictive aluminum oxide begins reforming on the surface as soona s the air hits it.
You must not use a tungsten that's been sharpened by something that's been contaminated with other metals. You must not use a wire brush / grinder / etc that has prepped for other metals. Stainless steel brushesh only.
scotchbrite pads are good, but not as aggressive as a good grinder, or sand / emory paper.

Stop using brake cleaner. The petrolium leaves residue on the aluminum that must be cleaned off. This is why we use acetone. It's just as bad for your body, but will evaporate from the metal very, very readily. Simplky green, etc are also good, but not as potent as acetone.


Unless you're leaking all your gas away don't turn your flow rate up so high.
15cf/h for a normal cup
7-10cf/h for a gas lens.
Turning it up higher causes turbulance when it leaves the cup / lens and that swirls the atmosphere back into the area, causing more contamination.

 

i don't use abrasives to clean base metals as i find it sometimes leaves the abrasive embeded into the base metal...= contamination. i use a stainless wire brush for everything. i have one for each different base metal... one for stainless, one for ms and one for alum. i keep them labelled so they don't get mixed up. no chemicals either. i don't think it necassary if you wire brush it good enough.

are you sure of the grade of aluminum? i've gotten piping from customers and it must have been from china, because it didn't matter how well i brushed/cleaned it, there was crap in the aluminum that just came out as i welded it. made for very difficult welding as it was constantly contaminated. i try to only weld my own material, that way i can control the quality. i don't offer a lifetime warranty on materials supplied by someone else unless i can verify the material grade.

 

snm95ls and i tried some mothers wheel mist (eagle one etching mag cleaner is the same thing) on an intake manifold. it worked wonderfully. i later tried it on a friend's transmission during his swap to clean it up, the results are amazing. just be sure to use gloves, b/c even though it's a weak concentration, it's still acid. the more you let it sit, the more grime it can take off, and a wire brush can help the process along. it doesn't even need a ton of pressure to wash it off, we used a sponge and just wrung it out over the top of the transmission to wash it.

 

Acid is the only way of cleaning dirty aluminum. MEK it's a strong cleaner and is a great before weld cleaner.

Randy

 

best way to clean aluminum is an aqueous solution of potassium hydroxide

 

If I can't see visible dirt on aluminum, like it's sat in the mud or something, I don't clean it at all.

The plant I work at welds on anodized aluminum all day long. A little oxidation isn't going to hurt you.

Post up some pics of the welds, and it will be a lot easier for people to give good tips.