Cleaning Aluminum

[tom86951]

As the title states, what's the best way to clean aluminum for TIG welding? I've been using acetone for grease and a clean ss brush for the oxidization, but often the aluminum needs a more abrasive cleaning to start. Side grinders and flappers seem to leave grit behind and steel files are slow... What's the best way?

[motolife313]

Try acetone then carbide burr. Then a little preheat before welding.when I acetone then brush I acetone again becuase the second time you acetone after brush the rag will be nasty again from the brush.

[tom86951]

Carbide burr -- on a drill you mean? Won't that chew up the aluminum pretty fast?

[That Guy There]

Flap disc that are made for aluminum work great. If not a flap disc coated every so often with soap or wax of some type to stop clogging.

Is this new or used/ been exposed to the elements aluminum?

A quick wipe down with acetone and let the cleaning action of the arc do the work.

[Willie B]

Some here will be horrified I'm saying this; When I have to grind because of heavy oxidation it leaves fine gouges, if I then wipe with acetone, it leaves little bits of lint from the cloth. I use acetone when the aluminum is smoothest, am careful to only grind the area where filler will stick, any other is done with brass or stainless hand held brush. Zap showed a technique using a stainless toothbrush and acetone. I do use a Norton Blaze disc, but stop as it wears 1/2 way using it for finish work or other purposes. A worn one I believe leaves the residue of the adhesive holding the abrasive to the backer.

[HT2-4956]

Try acetone then carbide burr. Then a little preheat before welding.when I acetone then brush I acetone again becuase the second time you acetone after brush the rag will be nasty again from the brush.

You must be building stuff for NASA.

Most of the aluminum stuff I've built (for use here on the surface of the planet) just gets welded together with out any elaborate cleaning procedures.

[Gamble]

On a rare occasion I use acetone. Can't even remember where it's at, that's how often I use it.
I use nothing for the most part, if it had dross from plasma I willl flap disc it.

[motolife313]

Carbide burr -- on a drill you mean? Won't that chew up the aluminum pretty fast?

Not sure what you mean when you say (or a drill). I use a 1/2 inch double cut carbide burr egg shape on a 1/4 inch shank. I don't put any pressure on it just enough to get to clean AL. Single cut burr will make a clean cut. Sorry I didn't see it said on a drill. Try it in a drill it should spin fast enough AL is pretty weak

[Econdron]

I'm not super educated in this, but I the reason you clean aluminum is because the oxidation on there melts at a temperature 2.5-3 times higher than that of the aluminum. So the weld puddle is not hot enough to melt the oxidation and you get little inclusions in your weld. Oxidation I believe is a form of a ceramic. Ceramics are also what are used in your grinding disks so same goes with grinding residue left in the aluminum. When I clean aluminum, I brush off the oxidation (if there is any), then just wipe with a rag. I would say 99 times out of 100 this is fine. If your welds will be subjected to some pretty substantial testing, if they see any contaminants in the weld, they will fail you. Oh, I also remember seeing a tip that you should only brush in one direction (forward and back, OR side-side) because if you do both, you end up just burying the oxides in the base material.

[Gamble]

You are right, but the AC wave going from negative to positive will break up the oxide layer. There is a technical term for it but I forgot what it's called.

[weldinON]

You are right, but the AC wave going from negative to positive will break up the oxide layer. There is a technical term for it but I forgot what it's called.

You may be thinking of ionic bombardment.

Here is a link that should give some ideas on cleaning aluminum:

http://www.alcotec.com/us/en/educati...ler-Alloys.cfm

[Willie B]

Another term I like is cathodic etching. In the workpiece negative (EP) half of the AC cycle electrons travel rapidly from the oxide coated aluminum object being welded. Simultaneously, ions (atoms with too few electrons to be balanced) bombard the workpiece. It is easier for me to wrap my brain around the concept of an electron exploding from a molten pure aluminum puddle splashing a tiny particle of non melted aluminum oxide away, than the sandblasting effect of returning ions from the tungsten. In either event, let it be understood the cleaning takes place only when electrons flow from the work to the tungsten. Hence the value of balance control in a welder. Experts however, can manipulate even a primitive welder to optimize the etching. Tight arc length, surface cleanliness, good gas coverage, and other technique I know nothing about, make Zap and hundreds of experts turn out flawless despite the lack of technology.

Why then not weld with DC EP all the time. This process works OK with very small parts, at very low heat levels. At higher heat levels, it melts the tungsten, causing arc wander, and worse; tungsten splatter, which ruins a weld. The word penetration is used often, but seldom defined. It means not only welding to the bottom of a joint, but also wetting well with a complete bond with the filler and workpiece. Ratios high in EP don't soak as well, arc is less concentrated, less of the total heat ends up where it is needed, more becomes HAZ.

[AluminumWelder]

Just buy a stailess steel wire wheel around 3" diameter and put it in a cordless drill on slow speed.
that's what I do when I am doing a lot of repetitive work,
most of the time a stainles ssteel tooth brush works fine and isnt' that much slower then the drill.

however the drill is great if you are craking stuff out and need to clean 20 tubes at a time all lined up side by side,

dont' use an angle grinder wire wheel they spin waaayy toooo fast, just smears the metal instead of cleaning it.
also every once in awhile reverse the rotation of the drill so the wire wheel stays like new.

always going the same way will tilt the wires in that direction and makes them less effective.