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mig welding aluminum

5K views 12 replies 7 participants last post by  NEW INTERIORS 
#1 ·
I practiced mig welding aluminum today. I had a lot of trouble getting a good start to my weld. Once I got going I had what appeard to be a good weld. Can anyone offer a suggestion as to why Im not getting a good start?

Im using a millermatic 210 with a spool gun.
The aluminum is 1/2"
 

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#4 ·
Pre-heat the material. Your problem is that it takes several inches of weld before there is enough heat in the base metal for things to go smoothly. This is the same reason that TIG is the preferred method on aluminum, you use the TIG torch to heat the aluminum at the start of the weld before adding filler rod.
 
#7 · (Edited)
I use a very fine sanding pad,And lightly hit it,When the machine is set right and the alum is clean right,You shouldn't have to pre heat it.You should only have to pre heat it if your machine isn't big enough.Don't be scared to run it a little hot. :)

I like to use these sanding disc.(But make sure it's a fine one).. :)
 

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#9 ·
You can't use 75/25 sorry to say, it sure would make things simpler (and cheaper) if the mix was that versatile but unfortunately it's not.

From the looks of the welds in that pic a tad more heat would probably help and some pre-heat would help also, especially on heavier stock. The reason the weld does not start out very good is, as ericnova pointed out, the material is sinking off the heat too fast and as it becomes hotter from the weld the bead will smooth out, pre-heating would solve this but just welding a little hotter would make a big difference too. Clean throughly with a stainless steel brush and make SURE the brush has never been used for anything else. A common mistake is to grab up a brush that has been used for various other chores thinking because it is stainless it will be fine but if it is contaminated it could easily cause problems, don't use your Aluminum cleaning brush on carbon steel (especially important when TIG welding and critical when using Oxy/Acetylene). Those sanding discs New Interiors mentioned are also an excellent way to clean Aluminum and are my first choice unless a brush is the only thing practical to reach into the joint.
 
#12 ·
aluminum welding

My old neighbor in Calif used to build circle track cars and I always had him do my critical welds. He said some of the made in China sandpaper will contaminiate the metal because of the adhesive they use. He always cleaned the parts with acetone as the last step.
 
#13 · (Edited)
timothale said:
My old neighbor in Calif used to build circle track cars and I always had him do my critical welds. He said some of the made in China sandpaper will contaminiate the metal because of the adhesive they use. He always cleaned the parts with acetone as the last step.

Never had a problem using the pad's,And never had to use Acetone,And never had to pre heat any of the Alum I did, :nono: I did ''ALL'' the Alum work,For one of the biggest (if not the biggest,,I think he is)offshore boat company in the world for about 10 years before I became disabled. :) He also own's a bunch of shipyard's that only build's his boat's. :) 300 foot supply boat's and Ice breaker's.. :)
 
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