The proper method for cleaning aluminum

[Al Wohlstrom]

I know there area few of you that are good at tig welding. What is the proper method for cleaning aluminum prior to tig welding? I use a stainless steel brush that is used only for aluminum, clean with acetone, and then heat with a torch to remove any moisture. Any other tricks?

[Terry Oxandale]

I'm not "good" at TIG welding, but it is vastly improved when I put it in my wife's big oven and preheat it (not possible with larger pieces).

[Al Wohlstrom]

Originally Posted by blueovalz

I'm not "good" at TIG welding, but it is vastly improved when I put it in my wife's big oven and preheat it (not possible with larger pieces).

I know that cleaning is important, and brake cleaner is definitely not to be used, any cleaner or solvent that works the best?

[Garry]

Make sure that the solvent is not toxic when breathed!
Garry

[Terry Oxandale]

Acetone or "low temperature" lacquer thinner (high volatility) works well.

[Phil]

AL:
Aluminum oxidizes almost immediately when cleaned. If the piece is particularly oxidized I use a cleaner that is a mild acid available at any welding supply, and it really strips the metal, then weld asap.
Most pieces can simply be cleaned with a scotch brite then welded. Most of the new welders use a modified arc which produces a cleaning effect in half the ac cycle, and new material can be welded with little or no cleaning.
Glass beading or sand blasting will produce really poor results, and I don't recommend those methods.
The proper tungsten, gas,( or mix of gases), and machine settings all have effects on the quality and appearance of the welds.
Let me know what your setup is and I can give you a few guidelines.
Good luck
Phil

[Al Wohlstrom]

Originally Posted by Phil

AL:
Aluminum oxidizes almost immediately when cleaned. If the piece is particularly oxidized I use a cleaner that is a mild acid available at any welding supply, and it really strips the metal, then weld asap.
Most pieces can simply be cleaned with a scotch brite then welded. Most of the new welders use a modified arc which produces a cleaning effect in half the ac cycle, and new material can be welded with little or no cleaning.
Glass beading or sand blasting will produce really poor results, and I don't recommend those methods.
The proper tungsten, gas,( or mix of gases), and machine settings all have effects on the quality and appearance of the welds.
Let me know what your setup is and I can give you a few guidelines.
Good luck
Phil

Thanks Phil, very nice looking weld. I noticed if you are welding on a large piece it acts like a heat sink and is tough to get hot enough.

[Brian Kissel]

We use argon, with helium added to it. This helps float the impurities out of the weld, and results in next to zero porosity.

Regards Brian

[Phil]

AL:
Very true on heavy or large surface pieces. Also it is necessary to develop a proceedure for thin materials such as when fabbing a tank or welding thin tubing.
Open edges need to be welded first, then work towards them as they will melt away if you just run the bead towards them from a heavier spot.
I usually pre-heat larger pieces to get a uniform weld, and to cut down on current requirements at startup. It is not unusual to start at 175-200 amps and wind up with too much heat even at 100, the material really soaks up heat. It may be necessary to cool the part and go back to it to avoid the excessive heat build up.
Also be careful when handling a really hot piece as gloves can introduce nasty stains in the surface that are hard to remove.
Pre-heat is particularly useful when welding a thin part to a thicker one, until both are close to equally hot.
As Brian mentioned there is a nice helium/argon mix that works well, generally I use straight argon unless the job has certain requirements or I need a particularly nice looking part.
It may also be advantageous to back purge small tanks as you build them to avoid snots and porosity on the inside, this can be done right off your existing gas flow with a Y adapter and a small valve.
Get some scrap pieces and try your hand at different weld configurations to get a feel for the way the material behaves. Positioning means a lot, and you will find that you will get a preference for weld position and direction to produce the best work.
Hope some of this helps
Phil

[Thomas Rouw]

When welding very old or dirty cast alluminium stuff like thermostat housings or 'like last week' a repair/build up weld on a lotus elan cast upright where the circlip groove had almost rotted away completly.
I allways clean up the part really good with a thinner solvent to take most of the embedded oil/dirt out of the pores, then soke it really good with water and degreaser, let dry completly. and then make a few clean-up runs with the torch, 1st with balance quite high and low current, 2nd a little less cleaning action and a little more current and so on until I have a neat surface again to start the build up of material on or to have a neat join-seam on the broken parts to start welding on.

make sure the cleaning runs are done a a very steady pace and don' t put in tomuch heat in this stage or it will crack later on.

on new material, I use 100% argon, and a small or large alloy only stainless brush and a little cleaning action on the balance setting of the machine, when th T70's ready we'll see wheter my recent fab work on the tanks and coolant system will hold up, last months presure testing says it will. :-)

I am by no means an expert welder, just a hobiest with a nice machine.
So it might not be all out correct way of doing it, but it has served me for years, and I have not had a repaired part broken again.

Grtz Thomas

[Al Wohlstrom]

Speaking of machines, what size welder are you guys using. The one I'm using is a Miller 200 Syncrowave. 1/4" aluminum is the ceiling for this machine.

[DaveM]

I've got the same Miller Synchrowave Al. Works great up to 1/4" like you say. Tried the different pulse settings, but haven't been able to analyze what difference they make. Any advice?