best way to clean/cut aluminium?

[bigwillyz]

hi whats the best way to cut/clean aluminium?
i only ask as at the moment i use 1mm cutting discs
and flap wheels to clean an area before welding.
i keep getting black spots in the weld.
is the cutting disc and flap wheel contaminating the alloy?

thanks mike

 

[hotrodder]

If the discs aren't aluminium specific (cutting) and/or reserved for aluminium only (all abrasives) then probably yes. Plasma cut edges are generally horrible to weld unless sanded back a little too. Couple of places i do aluminium welding for... No idea how they manage it and i've forgotten how many times i've told em that but anything that they've fabbed never welds as nicely as stuff i've done from start to finish even if i go OCD with cleaning it up/pre weld prep.

SCM abrasives are good for prepping large areas of oxidised/old ally, like scotchbrite seams can trap 'fluff' from the disc/pad so best avoided when say repairing a crack or similar. Those clean 'n strip discs work well too. Nice clean new stuff i typically just scrape the cut edges with a knife or deburring tool, everything in between a stainless wire brush is probably the best/simplest

Don't discount filler wire if it's been around for ages, some scotchbrite and a solvent wipe can transform results with old wire. I'm assuming you've played with AC balance and/or not got biased fully towards EN?

 

[chap]

Is it MIG or TIG your using?

I use guillotine, shears, hacksaw, cutting discs.
Do get a bit of contamination with cutting discs, also just having any dust even ali dust, gives a crappy weld.
For best welding i clean any muck with solvent (brake and clutch cleaner; flashes off really fast) and wire brush using a stainless brush.
Do you have sufficient Argon flow?

 

[shenion]

Beware using brake cleaner, you can get phosgene poisoning.

 

[hotrodder]

Brake cleaner in the UK is generally, if not always, the non-chlorinated variety (blend of acetone, hexane etc) so no phosgene but good point, always worth checking the label. Isopropyl alcohol is a nicer alternative but typically have to go out of your way to buy it at sensible prices and/or in worthwhile quantities

 

[graffian]

I have been buying if from Toolstation, there is a branch near and the price isn't bad, under two quid. It's isopropyl alcohol, which you can buy a lot cheaper as a liquid but I find it much more convenient as an aerosol.

 

[davenport]

jigsaw with a T127??? bosch blade i think...

failing that the circular ripsaw with a specificly toothed blade...

VERY NOISY and messy but works VERY well on 3 and 4mm fuel tanks...