Knowing how to braze aluminum can be helpful when you need to complete a series of repairs. It is a quick and inexpensive alternative in case of leaks, cracks or holes in aluminum composite materials, or very often even when air conditioning appliances need to be repaired. Compared to welding, the process for brazing aluminum is cheaper, more practical and does not require a very high voltage.
Steps
Step 1. Put on non-flammable clothing, gloves and safety glasses before starting the brazing process
Step 2. Remove dirt, oil, paint or other debris from the area where you need to braze
Use a degreasing solvent to remove the oil and grease. Depending on the size of the area, you may need to sandblast it or use an emery cloth, grinding wheel or file.
Step 3. Lock or hold the piece to be brazed
Step 4. Use a brush to apply the appropriate flux to the temperatures and metal
A multipurpose flux works well at various temperatures, so it is useful for any type of brazing. Add it by dipping the filler rod in the fondant. You can also skip this step if you are using flux coated rods, which apply it directly during the brazing process.
Step 5. Heat the repair area with a propane or acetylene welder until the aluminum turns orange
This is the effect that is obtained when the metal reaches high temperatures. Once the fondant is applied, it should change color or lighten all over.
Step 6. Apply the filler metal by melting the rod along the crack or fitting
The heat will melt the filler metal in the area to be repaired. Move the soldering iron flame by turning it on and off, as needed, to melt the wand.
Step 7. Remove the flux after the filler material has solidified by immersing the part in hot water or pouring it over the repair
The fondant will fall apart. If it doesn't come off, use a wire brush to gently scrub the brazed area when it's still wet or submerged in hot water.
Step 8. Sand the area with an emery cloth after the metal has completely cooled down
Step 9. Coat the area with a rustproof coating if you have not completed the work in this part
Advice
- Heat the whole piece, not just the area to be repaired, to avoid warping the aluminum.
- To add flux, dip the filler rod in flux during the brazing process.
- If the filler material thickens, pass the flame from the welding machine throughout the brazed area, to melt it again and smooth it with the rod.
- If the filler rod gets stuck in the area to be repaired, do not pull it. You risk breaking the fitting you made or the repair you made. Free the filler rod with the welding machine, trying to melt the metal that blocks it.
- If you are repairing a large hole, use a backing material, otherwise the molten metal from the brazing can drip into the hole.
- Don't save when you apply flux. Protect the metal from oxidation.
- By cleaning the area you want to braise, you won't run the risk of holes forming. This will also reduce the amount of harmful smoke that is produced during the brazing process.
Warnings
- Do not apply heat directly to the connection area. Since the filler metal penetrates by capillarity between the pieces to be assembled, the heat must be applied uniformly over the entire area surrounding the fitting, allowing the brazing metal to liquefy and flow into the joint area.
- Flux becomes difficult to remove if the metal has overheated or has been applied in minimal quantities.
- Flux fluoride must be used for corrosion, not chloride.
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Brass Al thin plate braze1 Be careful to ventilate the room where you carry out the brazing process well: the smoke that is produced can be harmful.
