TIG welding aluminum turning black and blobbing

[jtweld]

I have been trying to weld plain mill finish 6061/6063 aluminum angles together. Prior to welding I use a file or stainless steel wire brush to clean around weld area. Shortly after initiating the arc, the joint that I am trying to weld turns black with soot. If I continue with the arc the aluminum anlge at the joint will blob up, and fill with porosity embedded with black soot, this get worse if I try to add filler wire. I Then use a die-grinder with a burr to remove remove the mess and retry. What is going on here? The supplier claims that the aluminum is plain and not anodized. I have welded aluminum with success before, this has me stumped. My welder is a MILLER Syncrowave 180 SD. I am using Argon gas at 30 CFH. The filler I use is either 4043 or 5356. Any assistance here would be great help, my project is starting to look pretty ugly.

[zapster]

the only thing that equalls black soot is contamination...
the puddle "balls up" because of it..its not really "melting" into a puddle rather its just "floating" around on top of it...
your tungestion could be the culprit right off the bat...

are you grinding it on a stone for tungestion ONLY?

acetone everything before you start...
front back sides underneeth..

...zap!

[ZTFab]

Sounds to me like the machine is still on DC .....did you switch the machine over to AC?

[zapster]

Originally Posted by ZTFab

Sounds to me like the machine is still on DC .....did you switch the machine over to AC?

as i smack myself on the side of the head..

i did'nt even think of that..
good catch!

...zap!

[ZTFab]

Ha...I only know because I've done it. After balling my tungsten with DCEP, I've accidentaly left it there and...whoops!!!!

[Joe H]

Black soot and porosity, couldn't those be symptoms of a gas problem?

[riley mcmillan]

I think Joe H is probably right. It is very rare but I have got contaminated argon from time to time. Sometimes the dealer will fill your bottle from a battery of bottles and if they don't purge the lines properly, you can get bad gas. One time by mistake I was given a mixture which I immediately took back.

[ZTFab]

Joe and Riley...that is a definite possibility.

One of the reasons I suggested that it may the wrong setting is that jtweld didn't mention that he tried changing bottles...I ASSumed that he has welded with his current bottle of gas.

I too have received "bad" gas...and boy was I mad!
It was a couple of years ago. I had just exchanged my only bottle for argon on a Friday at closing time (for Airgas not for me, I'm self employed!!!) got back to my shop to finish welding a roll cage...and !!!

[Joe H]

I have even forgotten to open the tank valve before. Took me WAAAAAAY too long to figure it out too. I blame the beer.

[TJS]

30 on the gas seems kind of high. I am assuming you are using pure argon. Sounds like the gas is hitting the work and then oxygen is getting swirled in because of the high velocity of the gas. Try turning it down to 17. Note this is after you have checked all of the above. Please give us some more information on the machine settings. I had a 180SD and it was a great machine to learn on.
Thanks.
T.J.

[gnm109]

Originally Posted by TJS

30 on the gas seems kind of high. I am assuming you are using pure argon. Sounds like the gas is hitting the work and then oxygen is getting swirled in because of the high velocity of the gas. Try turning it down to 17. Note this is after you have checked all of the above. Please give us some more information on the machine settings. I had a 180SD and it was a great machine to learn on.
Thanks.
T.J.

I agree....30 seems high. I do TIG with argon at 20-25 SCFH and it works well. It could very well be contaminated gas also.

[jtweld]

Thanks for all of your input. Had Our Miller rep stop by Wednesday, we found that the fitting for the gas/power cable inside the torch body was slightly loose; which could draw in air, thus contaminating the gas (good call on that). This also explains why it would weld good at times, because of the depending on the position it is held it could leak or not.