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TECH TALK
Demystifying
Aluminum
The process isn’t difficult, just different
S ABOVE: Annealing the aluminum is a critical first stage in cosmetic aluminum repair. This process softens the metal and makes it easier to work with. However, annealing should not be used on structural parts, for exactly that reason.
ince the 1900s, aluminum has been used off and on at least three times for domestic vehicles. A 1910 Model T Ford had an aluminum hood, so aluminum is nothing new to our trade. Now we’re in 2017 and aluminum is being used again. It’s time to learn some new skills and take the mystery out of aluminum repair. We must realize that aluminum, high-strength steel (HSS) and mild steel are very different materials. This makes the procedure for each repair different. Not difficult, just different. The first difference is that aluminum must be annealed before it can be worked or welded. If you don’t do this, the repair will crack. Period. This applies to all types of aluminum, from the 1000 to the 9000 series. Not all of those alloys are used in automotive applications. For more on this, please see “Aluminum Designations” on page 33.
The first step in annealing aluminum is to heat the damaged area up to 400 to 600 degrees Fahrenheit (204 to 315 Celsius). That maximum temperature is important, as the alloying element may fume out. Zinc, for example, is used in the 7000 series and will fume out at 788 degrees Fahrenheit (about 420 Celsius). Less heat is better than more in this case, but you must heat it. The next step in annealing is to rapidly cool the area using a wet cloth or compressed air. A digital thermometer is a great tool to check the temperature. Just point the hand held gun at the surface, pull the trigger and it will read the surface temperature of the aluminum. Annealing essentially softens the area to be repaired. The interesting thing with aluminum is that you can go back as many times as you need to soften the area.
august 2017 bodyworx professional
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