Deleted
Deleted Member
Member since January 1970
Posts: 0
|
Post by Deleted on Dec 15, 2013 22:58:26 GMT -5
why does 'lummie require AC to weld?
|
|
jamesp
Cave Dweller 
Member since October 2012
Posts: 35,999
|
Post by jamesp on Dec 15, 2013 23:54:13 GMT -5
I don't know. I welded 10 meter satellite dish reflectors. The skin was 6061 about .10 and we used wire feed w/Argon gas pool. For Scientific Atlanta. 8 hours and nasty air.
Not my words:
Electrons need to flow welding work piece to welding tungsten in order to remove aluminium oxide. Excess workpiece to welding tungsten electron flow builds heat at the tungsten tip therefore alternating this process enables the oxide to be removed and heat to build at the job for penetration. A balance control can therefore give more cleaning or more job penetration by adjusting balance to be more positive or more negative.
No comprende except to remove oxides at job
|
|
Deleted
Deleted Member
Member since January 1970
Posts: 0
|
Post by Deleted on Dec 16, 2013 0:05:21 GMT -5
I can turn that into redneck everyday english.
If you have very oxidized 'lummie, then you need more positive than negative (or the reverse, I am not sure) and to get deeper penetration of the weld and better fill, then you need more of the opposite (whichever that way that works).
For thought experiment:
With basic 60hz AC we get a 50/50 ratio of positive and negative current. Modern square wave machines will allow you to control the length of time you are negative vs. positive that for better penetration or cleaning.
Consider you could still have 60hz AC that is artificially 70% positive current and 30% negative.
Your MIG for 6061 MUST have had AC. My DC machine WILL NOT WELD 'lummie. Plus the wire doesn't have 'sectional strength' to be pushed thru my hose. It binds up from friction.
|
|
jamesp
Cave Dweller
Member since October 2012
Posts: 35,999
|
Post by jamesp on Dec 16, 2013 0:11:50 GMT -5
Always been a stick welder except that 6 month period. It was easy to weld with the argon flow. Lots of black smoke and wood shop buggars.
|
|
Deleted
Deleted Member
Member since January 1970
Posts: 0
|
Post by Deleted on Dec 16, 2013 0:26:03 GMT -5
MIG/Argon is awesome for steel too. The bead is almost TIG-like but smoother. A good TIG weld looks like a stack of nickels. A good MIG weld has much closer ridges in the bead. Love my MIG|GMAW. Want TIG|TMAW, need SMAW lol
love the acronyms.....
|
|
|
|
Post by 1dave on Dec 16, 2013 11:44:37 GMT -5
why does 'lummie require AC to weld? I think the big problem is that warm aluminum oxidizes so readily. In the 60-70's they experimented with using aluminum wire in housing. The damn stuff would turn to aluminum oxide powder inside the plastic insulation and they finally got smart enough to give it up. Lots of homes had to be torn apart and re-wired. |
|
Deleted
Deleted Member
Member since January 1970
Posts: 0
|
Post by Deleted on Dec 16, 2013 13:00:02 GMT -5
why does 'lummie require AC to weld? I think the big problem is that warm aluminum oxidizes so readily. In the 60-70's they experimented with using aluminum wire in housing. The damn stuff would turn to aluminum oxide powder inside the plastic insulation and they finally got smart enough to give it up. Lots of homes had to be torn apart and re-wired. The real problem with home wiring, as explained to my by the fire captain (who is a part time welder) is that aluminum wire physically moves when energized. So after many thousands of times turning the lights on, the wire broke and then soon the house would catch fire from sparking. He knew which neighborhoods the aluminum wires were in and advised against buying in the neighborhood. They are still around all over SoCal. Thanks for the welding info. |
|
#10 - Thou shalt not covet thy neighbor's rocks