Braze Aluminum
Knowing how to braze aluminum can be a useful skill for anyone who is faced with a variety of at-home repairs. Brazing aluminum is a quick and inexpensive option for repairing leaks, cracks, or holes in aluminum and is often found in air-conditioning repairs. When compared to welding equipment, aluminum brazing equipment is inexpensive, portable, and does not require high amounts of voltage.
Steps
- Wear non-flammable clothing, gloves, and safety goggles before you begin the brazing process.
- Clean all dirt, oil, paint, or other residue from the area to be repaired by aluminum brazing. Use a degreasing solvent to get rid of oil and grease. Depending on the size of the repaired area, you may need to sandblast the area or use an emery cloth, grinding wheel, or file.
- Clamp or support the piece to be brazed.
- Use a brush to apply the flux appropriate to the temperatures and the metal. An all-purpose flux covers a wide range of temperatures and is beneficial to have on hand for general purpose brazing. Add flux by dipping the filler rod into the flux. You may also use flux-coated rods to eliminate this step. The flux-coated rods apply the flux during the aluminum brazing process.
- Heat the repaired area with a propane or acetylene torch until the aluminum shows an orange bloom. This happens when the metal gets very hot. Once you apply a flux, it should change colors or turn clear throughout.
- Apply the filler metal by running a brazing rod along the crack or the joint. The heat of the metal will melt the filler into the area needing the repair. Move the flame of the torch on and off as needed to melt the rod.
- Remove the flux after the filler material has solidified by dipping the part or pouring hot water on the repair. The flux will flake off. If it does not come off, use a wire brush to gently scrub the brazed area while wet or still in the hot water.
- Polish the area with an emery cloth after the metal has cooled completely.
- Coat the area with a rust-resistant coating if you are not immediately finished with the area.
Tips
- Heat the entire piece of material and not just the repair area to avoid warping the aluminum.
- Add flux by dipping the filler rod into the flux when brazing aluminum.
- If the filler clumps, run the flame of the torch across the brazed area and remelt it and smooth with the rod.
- If your brazing rod becomes stuck to the repair area, do not pull the rod. This may disrupt your replaced joint or disrupt the repair. Melt the brazing rod with the torch until it releases.
- If you are repairing a large hole, use backing material or the braze may drip into the hole.
- Don't skimp when applying the flux. It protects the metal against oxidation.
- By cleaning the area you wish to braze, you can eliminate the formation of holes. It can also decrease the amount of harmful fumes that form during the brazing process.
Warnings
- Do not apply heat directly to the joint area. Because brazing works by capillary action, heat must be applied uniformly to a broad area surrounding the joint, allowing braze alloy to become fluid and be drawn into the joint area.
- Flux becomes difficult to remove if the metal was overheated or if too little was applied.
- Corrosion, must be use Fluoride Flux not Chloride Flux
- Be careful to have good ventilation wherever you are brazing. Fumes from the brazing process can be harmful.
Things You'll Need
- Non-flammable clothing
- Gloves
- Safety goggles
- Degreasing solvent
- Sandpaper, emery cloth, grinding wheel, or file
- Brazing rod and flux paste or flux-coated rods
- Brush
- Torch
- Wire brush
- Rust-resistant coating (optional)
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