What Makes An Aluminum Stud Welder Different?

(Figure 1) Aluminum studs with a brad on the face, are welded into place to allow straightening of the panel.
(Figure 1) Aluminum studs with a brad on the face, are welded into place to allow straightening of the panel.

Because more aluminum panels are being used on vehicles to reduce weight, you are more likely than ever to have to remove a dent in an aluminum panel where you can't get access to the backside of the panel to push the dent out. Aluminum dent removal equipment is available for pulling dents out of aluminum panels using weld-on studs similar to the way you pull dents on steel panels. But, do you know what's different about the aluminum "stud welders" compared to the steel "stud welders"? Most dent pulling systems for aluminum panels use a capacitor-discharge type of welding technology as opposed to a resistance-weld type stud attachment.

Why are they different? Simple, aluminum is an extremely good conductor of electricity. There isn't as much heat generated with aluminum as there is with steel when the current from a resistance welder is forced to go through the stud where it contacts the panel. Resistance welding needs electrical resistance to make heat, which fuses the metal. It's possible to resistance weld aluminum, but it takes a lot more energy! To overcome the physics, a capacitor discharge welder is used. These welders build up a great deal of electrical energy in capacitors that, when released, create a burst of energy that creates enough heat to fuse the aluminum stud to the panel. To help create enough heat to fuse the stud to the panel without burning a hole in it, the aluminum studs have a small brad on the face of the stud that melts from the surge of energy that is released during the weld, and helps fuse the studs to the panel so they can be used for pulling the dent out of the panel. Following dent removal, the studs are snipped off with side cutters, and ground flush with the panel, and the area is prepared for body filler.


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