72 How to Braze an Aluminum Bumper Reinforcement with Super Alloy 5 Aluminum Rod and Flux Repair Kit
A bumper reinforcement is a solid aluminum bar that reduces the impact of a collision by absorbing force and providing a cushion to the front and rear bumpers of a car. Bumper reinforcements or bumper bars primarily function to keep the internal engine parts safe in case of accident. Replacement parts can cost as much as $2500, so brazing these expensive parts with Super Alloy 5 can be the most cost effective solution. (Never braze a bumper reinforcement that has been bent or damaged, this video features a bumper bar with a cut that is easily brazed)
In this video, an aluminum bumper reinforcement with a 7 inch cut is repaired with Super Alloy 5 and an oxyacetylene torch. Oxyacetylene is required for this repair, since the aluminum part is large and dissipates heat quickly. The aluminum bumper reinforcement must maintain a 600°F temperature throughout the entire repair to properly bond the Super Alloy 5 to the parent metal.
Begin by using a Dremel tool or grinder to bevel the entire length of the crack. This step creates a groove which allows Super Alloy 5 to adhere to the parent metal. Next, braodly heat the aluminum bumper reinforcement to slowly bring the part to the proper working temperature. Briefly heat the end of the rod and dip it into the powder flux, then apply to the repair area. Watch the flux: when it transforms from powder to liquid, this is an indication that the parent metal has reached 600°F. Add the rod to the end of the crack and continue to alternate adding rod and flux to fill the entire crack. If the rod begins to ball up, the parent metal has cooled too much. Heat the parent metal until the rod begins to liquify and then add more flux to flow the rod out.
After completing the entire repair, remove the flux with warm water and a wire brush, then grind it down.
- Always keep your flux bottle as close as possible to the repair area, because every time you move your torch away, the aluminum drops approximately 100 degrees per second.
- Notice the technique: As soon as the rod began to flow, the heat is removed very quickly to avoid overheating the base metal.