Aluminum is a very thin metal that most welders would not attempt to braze using the metal inert gas (MIG) process. The reflective heat from MIG welding is, in fact, so hot that it can easily burn through soft aluminum. Using MIG to weld aluminum tubing has its own difficulties in that tubes have circular joints that are not conducive to a straight weld. MIG aluminum welding looks more uniform with a straight weld. To effectively weld aluminum tubes, several small weld puddles must be created after a constant weld speed is mastered.
Things You'll Need
- Spool gun
- Argon shielding gas
- Aluminum wire
Locate the spool gun's weld compartment. Connect the spool gun's weld cable to the positive stud. Remove the cover from the spool gun's canister. Unscrew the contact tip. Cut off six to eight inches of aluminum wire and straighten it with your fingers. Open the tension arm. Follow the spool gun manufacturer's recommendations to thread the length of wire through the gun.
Replace the canister cover. Close the gun's tension arm. Aluminum wire will be sticking out of the tip of the spool gun. Install the contact tip with a width corresponding to the diameter of the aluminum wire. Screw on the spool gun's nozzle.
Test the tension of the aluminum wire before starting to weld. Lay the wire against an insulated surface and feed it through the nozzle. If the wire bends upward without coiling over, then the tension is too loose. Follow your spool gun manufacturer's recommendations to increase tension on the wire. Increase tension and test the wire again. At constant speed feed, the wire will extend from the gun in a continuous coil.
Recess the tip of the aluminum wire by 1/8 inch.
Degrease and scrub the aluminum pieces to be welded with a stainless steel brush. This will remove oxides.
Set your spool gun's voltage and wire speed according to manufacturer recommendations. Align your tubes of aluminum with the welding surface. Point the aluminum wire at a 10 to 15 degree angle to the joint. Keep the spool gun nozzle about 3/4 inch away from the joint of the metals. Start a weld puddle.
Maintain a 10 to 15 degree angle while pushing the weld along the joint between the aluminum tube and its surface. Do not pull or drag the weld. Pushing the weld cleans the aluminum by allowing the argon shielding gas to go in front of the weld puddle.
Use a short, fast stitch motion until the weld is complete. This will require several weld puddles.
Tips & Warnings
- Metal inert gas welding requires the use of at least 14 gauge aluminum or the weld may burn right through the metal.
- Photo Credit welding project image by leemarusa from Fotolia.com
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