From wicker or wooden car bodies at the beginning of the automobile´s time to the luminous car bodies or the ones that can store energy, the automotive industry has lived in constant evolution. This is an evolution that encompasses all components of the car, and the body is not an exception.
When steel and aluminum were introduced as the preferable materials for fabricating car bodies, the industry knew that this was the path to follow. However, because of lower cost, they were mostly produced out of steel… this was the case until recently, when different types of high, or very high yield strength steel have been incorporated to reduce the vehicle’s weight and increase its structural resistance. This has also been the case for the introduction of plastic and carbon fibre.
This is why the use of better quality, and higher priced, steel is now a common solution. Thus, producers’ car bodies’ repair manuals have become full of acronyms which are not always easy to decipher. We can find baked hardenable steel (BH), high yield steel (HSLA), dual phase and complex phase steel (DP and CP), or ultra-high strength steel (UHL) among others.
In itself, aluminum is a material which, given its characteristics, benefits the manufacturing process of car bodies: less weight, malleability, different types of rolling production, good capability for impact absorption, etc. Some of its inconveniences are production costs, the binder systems, the fact that it is a softer material…
Also, its use implies a great designing effort since the classic binding systems are not valid and it demands a new way of thinking for both production and repair. Thus, it is easier to find it in spare parts (bonnet, flaps, doors, hatchback, crossbar, wheel arches…).
It has been for some years now that carmakers have regarded aluminum as an essential material for their cars’ bodies. In fact, Audi has been applying this solution in some of its car models, and Jaguar - Land Rover Group has also employed this material in the production of its latest models. Furthermore, most brands, particularly luxury ones, include it in some of their models.
Evolution in car bodies design and production has sought to benefit from the advantages of both steel and aluminum by the process of combining the two of them, which has led to the emergence of the hybrid car bodies. Depending on the particular needs, we can find ourselves looking at a combination made of complete pieces, modules, sections, or just a specific piece. Thus, the use of aluminum for certain parts, or independent subsets attached by means of screws, as can be the case for bonnets, hatchbacks, or doors, is becoming more and more usual. The same can be said about plastic materials. One must just compare a current vehicle to one some years older to check how the bumper’s surface, both front and rear, has broadened considerably, reducing the size of flaps and bonnet so much that, in some cases, the rear flaps have become mere holders for the lights.
Repairing hybrid car bodies requires having comprehensive knowledge of the product, identifying the type of parts meant to be mended and knowing the appropriate procedure that the automaker marks in the repair manual.
It is necessary to know which the cutting areas and binder systems are as well as how, when possible, to reproduce them at the car shop following the stipulated procedures set by the car manufacturer. In fact, in some cases, the same car manufacturers are the ones who select some car dealerships with specific training for hybrid car bodies, marking them as the only ones authorised to undertake the repair.
The properties that characterise aluminum determine the repair process of a plate of that same metal, given that it is less resilient (it must be worked with more gentleness than steel and by the application of more controlled efforts); is less elastic (risk of fissure or tear during the repair processes); has less hardness (being softer, the surface is prone to get marks or be overstretched); and has a bigger coefficient of expansion (applying heat over aluminium plates may cause deformations more easily than it does over steel plates). Also, it has high thermal conductivity and low electrical resistance, both aspects which affect the requirements for welding this material.
The necessity to adapt to these properties makes it mandatory to have specific tools, especially because of the risk of aluminium suffering from galvanic corrosion as it comes into contact with steel or any tools that had been used for repairing steel parts. That is the reason why all tools intended for work with aluminum are signaled by the color red at the car shops.
Repairing or replacing carbon fibre components does not require any specific tools, equipment, products, or training. Any of the products used for repairing fibre and glass fibre reinforced plastics can be used for the repair of panels, bonnets, covers, and doors.
However, this repair is not always easy, and it requires a skillful professional, which is why, when it comes to repairing carbon fibre, the damage and the time it would take to be repaired must be assessed and compared to the cost of replacing the damaged part. It must be taken into account, as well, whether a repair over this material would show, since it may have consequences when the car is being repainted.
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