Welding aluminum tubing is different than welding other metals due to the greater heat involved and the different properties of the aluminum itself. This article will discuss the proper techniques required for successfully welding aluminum tubing.
Step 1 - Cleaning and Shaping the Aluminum Tubing
Make sure it is clean. Aluminum is coated in a very thin layer of aluminum oxide. This coating is virtually invisible, but it will prevent proper heating and welding of the aluminum. Clean the aluminium by either spraying it with acetone or wiping the acetone on the pieces with a rag. Rinse the aluminum in water to remove any residue from the acetone dip and scrub the pieces to be welded with a stainless steel brush. The aluminum pieces should be shiny after this procedure.
Next, you have to prepare the ends of the tubes. Use a grinding tool and turn the ends of the tubing so that they turn in slightly. This is necessary to allow better fusion to each another.
Step 2 - Line up the Tubing
Line up two pieces of aluminum tubing on top of the heat sinks. The heat sinks are necessary because aluminum melts at such a high temperature that warping or damage to the tubing could result. The heat sinks will draw the heat away from the pieces. Clamp the pieces of tubing securely to the heat sinks and tightly against each other. The less gap between the two pieces of aluminum tubing, the better joint that will be produced.
Step 3 - Weld
Put on the heavy duty welding gloves and make sure that no skin is exposed during the welding process. Again, with the extremely high temperatures required for aluminum welding, it doesn't take long for any exposed skin to suffer damage.
Take the welding torch and welding rod and put a tack at the joint where the tubing connects. Turn the tubing ninety degrees and add another tack. Repeat this until four tacks have been added. Verify that the tubing has not twisted or become misshapen.
Step 4 - Welding the Aluminum Tubing
Now that the pieces of tubing are tacked in place, it's time to do the actual welding. You can use an "uphill" or "downhill" method, whichever is more comfortable for you. The trick to a lasting weld on aluminum tubing is all in the technique. Get the torch lit and have your welding rod ready. Touch the welding rod to the material so as to just leave enough aluminum on the joint. Lift the rod and move the torch forward or back, depending on which way you are welding and repeat the rod touch to the joint. This moving/touching procedure should take one second each time. This will create a strong welded joint.
Step 5 - Cleaning the Weld
After you are finished welding, use a grinding wheel on the aluminum tubing joints to remove any excess aluminum and clean up the joints.