Welding Aluminum on DC-

Date 07-30-2013 20:15 Edited 07-30-2013 20:52

Just started welding some aluminum on DC- for the first time, I had to test some welders on some 1/2 thick 6061. Wow is that a cool welding process. I couldnt believe how easy it is to pump heat.

So my question: Why does the aluminum still look contaminated on the surface when I am done? I used a fresh sanding disk and took off all the coating and made a fresh surface, fresh tungsten too. Once the weld was complete just a little wire brush and she was a stack of dime with much more penetration.

Could the coating on the filler rod be the culprit? I dont see how you can be so clean and it still have a dirt to it.

I dont have the best terminology haha so bear with me

Thanks
Jordan

By 803056

Date 07-30-2013 21:46

Jordan;

What type of grinding or sanding disk are you using to prepare the joint? They don't contain aluminum oxide by chance do they?

Al

By MRWeldSoCal (***)

Date 07-30-2013 22:23

Al-
Damn you know what they are aluminum oxide. Duh. should have thought of that one. Whats the best way to prep it for DC?
-Jordan

By aevald

Date 07-30-2013 21:58

Hello Jordan, since you are using DC- to produce the welds you do not have the benefit of the cleaning action of the DC+ side of AC. Even though you have thoroughly cleaned everything prior to welding you will still have an immediate oxidation of the surfaces of the welding area, prior to and during the welding and you will likely also have some of the "soot" from elements of the filler rod as they are consumed/mixed in the arc column and molten puddle during the welding process. I know there is a more technically correct description of all of this, but this is a quick and "dirty" explanation. I hope that I have given some understanding to what you are seeing. Good luck and best regards, Allan

By MRWeldSoCal (***)

Date 07-30-2013 22:26

Allan-

Also a great point, I know the AC does a cleaning job. now if i were to scuff up the filler rod and clean it really well could that cut it own?

By weldwade (***)

Date 07-31-2013 00:27

What shielding gas are you using? One thing you may also need is a dryer for the shielding gas. I built one years ago for less than $20 or you can spend a bunch more on a pre made one. Clean Clean Clean!!! Use a brand new stainless wire brush, don't use a cup brush on a grinder the rpm is way too high and can hurt more than help. If you need to power brush use a low rpm drill. A hand brush works really well. You can also use acetone for the final wipe down of the piece as well as the filler.

By Milton Gravitt (***)

Date 08-01-2013 01:26 Edited 08-01-2013 01:34

What welding process are you using. Are you using Helium if you are that is what making your weld black.
M.G.

By MRWeldSoCal (***)

Date 08-01-2013 15:27

We are using Pure helium, It is making for great looking welds but why the burnt edge on ignition?

By jwright650 (*****)

Date 08-01-2013 15:36

Preflow set long enough to make sure the gas gets there and covers the area before the arc starts?

By Milton Gravitt (***)

Date 08-01-2013 16:50

I think John hit the nail on the hesd. Before starting your weld listen to the cup and make sure the gas is coming out before the arc. We had a machine that would strike an arc before the gas would start. You had to get used to listing before welding.
M.G.

By cddolan74 (**)

Date 08-01-2013 13:38

if this is a inverter type of power source, remember hearing that when welding on DC- it left a cloudy film on the weld instead of the bright clear typically seen in AC. I played with a Mileer dynasty in DC- and loved that I could get a sharper arc off the tungsten in stead of the wide arc seen with AC.