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Last spring I took a one week spray pulse MIG welding class at Hobart Institute of Welding Technology. We spent two days welding groove welds on 1" steel and three days on 3/8" Aluminum in all positions. The spray pulse welder made it relatively easy to weld both of these materials out of position. For Steel we used a conventional MIG gun and for Aluminum we used a push pull gun. The steel welds were tested with a side bend test and the Aluminum welds were etched to verify penetration.
With this spray pulse experience behind me, I decided to try it out the spool gun that came with my MIG welder. I used 1/8" Aluminum stock because I have a lot of it and it is the thickness that I most often weld. I did the normal padding beads and welding test coupons to get the parameters dialed in as shown on picture 1. Overall it went well. The following parameters were used on all welds:
Lincoln SP250 MIG Welder
Lincoln A30 Spool Gun
20-25 CFH Argon Shielding gas
Coupons 1/8" x 2" x 6"
No preheat -- welded at room temperature (I actually let the metal cool off before I welded the 2nd side)
Push position of gun
No weave or step ahead
0.035" 4043 Aluminum wire
I noticed that there was a little cold lap at the start of the weld as shown on picture 2 & 3.
I believe that this could be several things could contribute to this:
For my next run, I increased the voltage to 20.5 volts as shown in picture 4 & 5.
This solved the cold lap problem but it created two new problems:
With this spray pulse experience behind me, I decided to try it out the spool gun that came with my MIG welder. I used 1/8" Aluminum stock because I have a lot of it and it is the thickness that I most often weld. I did the normal padding beads and welding test coupons to get the parameters dialed in as shown on picture 1. Overall it went well. The following parameters were used on all welds:
Lincoln SP250 MIG Welder
Lincoln A30 Spool Gun
20-25 CFH Argon Shielding gas
Coupons 1/8" x 2" x 6"
No preheat -- welded at room temperature (I actually let the metal cool off before I welded the 2nd side)
Push position of gun
No weave or step ahead
0.035" 4043 Aluminum wire
I noticed that there was a little cold lap at the start of the weld as shown on picture 2 & 3.
I believe that this could be several things could contribute to this:
- No hot run in setting on welder.
- Preheat of starting point of metal.
- Increase the Voltage
- Use a run in tab
- Metal thicker than 1/8" would be able to tolerated higher voltage.
- Could add some Helium to the Argon
For my next run, I increased the voltage to 20.5 volts as shown in picture 4 & 5.
This solved the cold lap problem but it created two new problems:
- Suck back on back side of plate.
- Undercut on top of weld.
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