Use a MIG welder with spool gun or push-pull gun
Use 100% argon shielding gas
Select aluminum-compatible wire such as ER4043 or ER5356
Match wire diameter to material thickness
Clean aluminum thoroughly with a stainless steel brush
Remove oxide layer, grease, paint, and moisture
Use dedicated aluminum contact tips and liner
Set correct polarity to DCEP
Increase wire feed speed for aluminum
Set voltage and amperage for the joint thickness
Keep the gun cable as straight as possible
Maintain a short stickout
Push the weld puddle, do not pull
Hold a consistent travel speed
Use proper joint fit-up and clamping
Preheat thick aluminum if needed
Practice on scrap before welding the final piece
Inspect the weld for porosity, lack of fusion, and cracking