Cleaning Aluminum 1

[nalves]

What is the right solvent to use for cleaning Aluminum (6082 T6) before welding? The parts to weld have been machined (turning and milling), using cutting fluids. The material has been recently bought, does it steel need wire brushing, after cleaned with the solvent?

Thanks.

 

[NickE]

I wouldnt wire brush it with steel, that seems like it would be a good way to induce Fe particles into the Al.

 

[TheBlacksmith]

You should brush the aluminum with a dedicated stainless steel brush (not used on or contamianted by any other material) just before welding. Aluminum oxides form relatively quickly and have a much higher melting point than aluminum, if left in place, either the aluminum gets overheating by the time the oxides melt or the oxides are entrained in and contaminate the wled.

 

[nalves]

Sorry, for my mistake, I wanted to say:"...does it still (not steel) need wire brushing"

I am asking about wire brushing, because the component is to be anodized (after welding) and as I said previously, the material is recently bought meaning it may have a smooth oxide cover, which mean it could be “easily” removed by the arc itself. (???)

What about the solvent? What to use?

Thanks

 

[rorschach]

99% Isopropyl alchohol or 99% acetone would be the solvents that most readily come to mind.

 

[weldtek]

All sources of contamination must be removed from the joint. It's a good idea to clean back an inch or so, more in cases where the possibility exists for contaminants to melt with the heat of welding and enter the weld area. The solvents mentioned by rorschach will work or MEK is another option. The caution is that these are all flammable. Stay away from chlorinated solvents. As TheBlacksmith notes oxides must be removed by either a chemical compound or by mechanical means ie. wire brushing. As noted use a clean stainless steel wire brush. Cleanliness is absolutely mandantory in producing sound welds in aluminum alloys.

 

[Voyager687]

I weld stuff like this regularly, so here's the trick to good aluminum welds.
1) If your parts are shiny, not dull,they don't need
brushing because they're not oxidized.
2) Brush marks usually look really bad after anodizing
because the color makes them stand out.
3) Almost any solvent will remove more than enough oil
film,but acetone,MEK,naphtha and denatured alcohol
all do very well.
4) The continuous hi-frequency setting on your welder
is what actually cleans away most of the oxidation
anyway.
5) THE ALLOY OF YOUR FILLER WILL AFFECT THE LOOK OF
THE ANODIZED FINISH MORE THAN ANYTHING ELSE. Check
with your supplier about color compatibility.

Alan L. Bass, toolmaker

 

[unclesyd]

Vouager687 makes a very good point concerning the color match with Al welding. If the required physicals allow it it definitely pays to match the base allow for for bare metal appearance and as posted check with the anodizer for matching after anodizing. At times this could take 2 different filler metals.

 

[weldtek]

Voyager687 makes some good suggestions, but I'd like to offer a small clarification to item 4. In GTAW welding the use of Direct Current is not common, rather Alternating Current is the current of choice, that being, because both DC+ and DC- offer certain advantages. DC+ offers the cleaning action referred to by Voyager687. The problem encountered in using Alternating Current is the fact that the current drops to zero and reverses direction twice in each cycle making for an unstable arc. The most common way to get around this problem is to superimpose a high frequency, high voltage current on the regular welding current.