Mig Welding Aluminum project Lincoln powermig 350mp & Stronghand BuildPro table

This is part 2 of 2 about mig welding an aluminum fixture using a Lincoln Powermig 350mp on a Buildpro table.

see the part 2 vid below

or click here if you missed part 1

First a recap of part 1.

This part was done to a blueprint and its made from water jet cut pieces of 6061t6 aluminum ranging from 3/8" (.9mm) all the way up to one inch thick ( 25mm). The base plate was 1/2" (approx 13mm) and there was a ton of welding on it...

Right away, I could tell I was going to have a distortion problem...

...so I clamped and tack welded the base plates together so that they would oppose each other.  I have found this to help in the past when welding simple base plates to square tubing.  If there are multiple parts, its a good way to limit distortion because not only is it a stiffener, but as each piece begins to draw, it helps pull the other straight.

After a good heating to 350f using a rosebud, the base plates came out pretty darn flat.

A few words about the powermig...

There are some things we all encounter with mig welding aluminum.

Here a just a few issues common to migging aluminum:

• Soot on  starts 
• cold starts due to high thermal conductivity
• craters that can crack,
  
• wire fusing in the puddle at the end of the weld.
  

This PowerMig has settings to help overcome all these things.

• pre and post flow for shielding gas to make sure the arc is shielded on start and at the end of the weld. ( it only takes a fraction of a second for pre flow and no more than 1 second for postflow)
• a run in setting to prevent wire stubbing on starts, and a hot start setting that lets you set a higher voltage and lower wire speed for about a second to overcome the tendency for cold starts on cold aluminum.
• also, there is a crater fill that is fully adjustable and will fill any crater however you like ...slightly filled just enough to avoid cracks, of fill slap up....very cool.

I am still messing with all the settings to find what works best and I will be  sure to add that info when I nail it all down.  But I am already making better looking welds than when I started.

I am still learning new things...for example, what causes soot, and settings that seem to get rid of it.  One thing is for certain, too much wire speed increases soot.  But not enough wire speed burns up tips.

There are sweet spots in there somewhere and I will find them. It might take a few bottle of argon, but it will be worth it to make this thing sing.

I have often said, that mig welding aluminum is harder than mig welding steel because practically everything that can go wrong on steel goes wrong worse on aluminum.  Finding that sweet spot is harder on aluminum, and temperature of the base metal seems to make way more difference than almost anything else.

With mig welding steel, things stay pretty consistent. Every time you walk away and come back, there are usually no surprises.

With aluminum, it can seem  like a different ball game every time. Changes in humidity, base metal temp, slight changes in wire speed or voltage, all have an affect.

Thats it for this video on the Lincoln PowerMig 350mp you can see part1 here in case you missed it, if you are interested in watching more mig welding videos or welding project videos just click on the words.