Working with Aluminum Panels

May 25, 2015 | Reply More

BMW’s quest to make vehicles stronger, lighter and more fuel efficient is never ending. In order to achieve these goals, new ways of thinking and  new materials are necessary. That translates into new repair procedures.

2008-bmw-5-series-535i

2008-bmw-5-series-535i

In an effort to both clean up the air we breathe and reduce petroleum consumption, government regulations require lower emissions and improved fuel economy. You may think this is a job for the engineers who build engines and powertrain management system. You would be right, but this is only part of the equation. Engineers design these systems to work with a specific load. The weight of the vehicle and its aerodynamics affect this both under acceleration and at speed. If you can lighten the load, you will take stress off of components, increase fuel economy and reduce overall emissions.

So, the weight of a vehicle is as important as any other engineering criterion in improving a vehicle’s overall performance. One of the efforts made by manufacturers to reduce weight is the increased use of aluminum. This light-weight metal can replace steel without sacrificing structural integrity and passenger safety. Of course, different construction techniques are required to maximize aluminum’s characteristics, and with these come new repair procedures. In order to provide your customers with the same safe body structure they had before any crash damage, you need to adhere to the proper repair techniques specified for aluminum.

Aluminum 101

You may wonder what has driven the change to aluminum.  First, aluminum is about one-third the mass of steel. But that doesn’t mean you can save two-thirds of the weight. First, aluminum is not strong enough by itself for automotive applications. It needs to be alloyed with other metals to exploit its characteristics. Also, if we want to maintain the same strength as steel we need to use more of this alloy. As a result of the need to be an alloy, aluminum has multiple manufacturing benefits. The most common form is sheets, but it can be cast or extruded to form sub-structures. Different alloy blends will highlight different characteristics and these are identified by the series number. For example, a 2000 series alloy has relatively more copper in it. This makes for a fairly strong, workable panel that can be easily stamped. A 3000 series alloy has manganese, which makes for a stronger panel. A 4000 series alloy will melt at a lower temperature, so is used in welding wire. In the 5000 series, aluminum is blended with magnesium, so in addition to being stronger it is also corrosion-resistant. This series is also strong enough to be used in sub-structures. By adding silicon to the 5000 series, you get a 6000 series alloy that is stronger yet. Adding zinc to the mix yields the 7000 series, which is both strong and corrosion resistant. This alloy is strong enough to be used in bumpers and their reinforcements. Whatever the alloy and depending on its application, on average the overall weight savings ends up around 40% over

 

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Category: Structural & Body, the bimmer pub

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