Bump aluminum

Aluminum is used more and more often today, including in body shop. For private screwdrivers and do-it-yourselfers, this also increases the chance of having to buckle an aluminum sheet instead of a steel sheet. What has to be considered when bulging aluminum has been summarized in the following guide.

Steel sheet gives way to more and more aluminum

Fuel consumption and exhaust gases are constantly being reduced. Therefore, more and more aluminum sheets are used instead of steel sheets. Until just a few years ago, only individual bodywork areas made of aluminum, complete alu carobes are self-evident today.

The decisive properties of aluminum

However, aluminum has completely different properties compared to sheet steel:

  • higher current conductivity
  • higher thermal conductivity
  • lower strength of welds (50 percent under steel sheet welding)
  • Alteration of the alloy on heating (bulges and becomes porous depending on the cooling)
  • Change of aluminum while driving
  • to some extent easier to recover than sheet steel

Anyone who has already dented sheet steel knows that the material is often driven here, so the structure is changed. Nevertheless, steel sheet retains its resistance. This is not the case with aluminum. Therefore, it should be avoided to drive aluminum or aluminum sheet.

Accessibility of the aluminum sheet from both sides

If the aluminum can be reached from the front and rear, push out the bump carefully and slowly. Use a rubber mallet and slowly knock the bulge outward from the inside. However, do not knock out the bump completely so that the material can not be overstretched.

To avoid is driving with a counter-holder, which is pressed firmly and is not flexible or elastic. This drives the aluminum. Instead, wood can be used to counteract this, but it is only applied loosely.

Accessibility of the aluminum sheet exclusively from the outside

In this case you can weld a bolt and carefully knock it out with a slide hammer together with the aluminum sheet. Again, the material may not be overstretched.

Remove difficult bumps and dents by heating

The heating and deformation of aluminum sheet should only be done if you have the necessary experience. The aluminum is heated until shortly before annealing and then cold quenched. Now it is brittle and can be processed with the Ausbeulhammer.

Then the aluminum is reheated until shortly before the hot spot, but now slowly cooled down. As a result, the aluminum gains elasticity again. This technique requires very good knowledge of aluminum, the heating of aluminum and the processing techniques. Even the slightest mistake can lead to sheet metal areas remaining brittle and simply breaking out over time.

Thesis after bulging

Now the aluminum surface is filled. In particular, the car manufacturers offer here different fillers, which can be applied analogously to the tinning of steel.

Tips & Tricks

This work will require you to sand the aluminum. Bear in mind, however, that an oxide layer will form immediately, making it very difficult for paints to adhere. Avoid completely removing paint and primer from the aluminum. For more information, see Oxidizing aluminum.

Video Board: How to Weld Anodized Aluminum - Bump Welding | TIG Time