Recently, we received queries on how to braze aluminum tubing.
Brazing, like soldering, is a way of permanently joining metals (including aluminum tubing) using a torch. There are many reasons why you may want to braze aluminum tubing. You can use aluminum tubing for jewelry, sculpture, making furniture, building or repairing bicycles and all sorts of projects for crafts and construction around your home.
Clean the metal. Dirt, grease or grime on aluminum tubing will prevent the brazing wire from melting into the seam or joint you want to braze. When folks have difficulty brazing, it is usually because the aluminum tubing is dirty. If the brazing wire does not flow, stop and clean your aluminum tubing and begin again. Clean any dirt with soap and water. Clean any grease with acetone. Clean any oxidation with sandpaper.
Flux the metal. Flux prevents oxidation from forming at the joint of the aluminum tubing when heated. Paint the seam of aluminum tubing with flux and the metal will not oxidize and interfere with the brazing wire moving into the seam. You can braze aluminum tubing without using flux, but it is easier to braze aluminum tubing using flux.
Arrange the metal. Brazing wire binds the seam of the aluminum tubing by capillary action when subjected to heat from the torch. If the aluminum tubing is flush, then the brazing wire will better melt into place. Use binding wire, a clamp, a third-hand or other other tool to hold the aluminum tubing still if gravity alone will not do so.
Use even heat. Heat the aluminum tubing evenly with your torch before adding the brazing wire. You will know when to place the brazing wire in the seam when the flux begins to bubble and the aluminum starts to turn a chocolate brown.
Melt the brazing wire into place. Place the brazing wire in the joint of the tubing. The brazing wire will begin to melt into the joint. Heat the brazing wire with your torch. Draw your flame along the joint. The brazing wire will melt into the joint until it is secure.
Allow the aluminum tubing to cool to room temperature.
* Use fire safety precautions when handling a torch.
* Work in a well-ventilated space when brazing
For related information on soldering see these GeltDesigns.com tutorials: