About Porsche Wheels

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I didn't write this I copy/pasted only. Go to the web site listed below and get the online magazine.
Reinventing the wheel every day at Porsche
No other self-contained component which requires relatively little development work makes such a powerful and impressive impact on the appearance and image of a vehicle as the wheels.
mold and remains there until it solidi- fies. Every cast wheel is X-rayed to en- sure that the microstructure is of the re- quired quality. The result of the process is the cast wheel, which is already clear- ly recognizable and which is then turned on the lathe, drilled and deburred. Flow forming is a metal forming process in which the wheel rim base is rolled out over a mandrel by one or more rollers. The diameter of the wheel and the thick- ness of the material can be changed at the same time. By rolling the wheel rim base, the Weissach engineers can re- duce the wall thickness of the rim by up to a millimeter without compromising its stability. During the forging process, the wheel is created under pressure from a solid block of aluminum in sever- al stages. The forging mold determines the result of the process. As forging in- volves high pressures and several phas- es of production, it is one of the most costly and time-consuming methods of producing wheels. The Porsche devel- opers make use of this process when manufacturing the Exclusive wheels for the Porsche 911 turbo. Regardless of which process is used, all of the wheels have one thing in common. They are all subjected to strict testing procedures by the Weissach engineers before they can be fitted to a Porsche. Each type of wheel must comply with predefined material, surface and strength specifi- cations. The criteria include tensile strength, strain, hardness and micro-
As well as looking good, wheels have a number of other functions. They form the direct link between the surface on which the vehicle is travelling and the power produced by the drivetrain. In ad- dition to influencing the overall appear- ance of the vehicle, the wheels also have an impact on its structural durabil- ity, comfort, dynamic performance and other safety features. For this reason, the engineers in Weissach are working every day on making wheels even lighter, more robust and more attractive. You could say that they are reinventing the wheel on a daily basis.
Complex development process
At Porsche the process of creating a wheel consists of three complex areas. The first of these is the definition and design phase, during which the engi- neers and designers specify their re- quirements for the wheel. Next comes the implementation phase when the strength of the wheel is determined and calculated and the drawings are created. The manufacturing process only begins after subsequent agreement with the suppliers. Porsche developers choose one of three production processes for the manufacture of the wheels: low- pressure casting, flow forming and forging. Low-pressure casting is used primarily for smaller wheels. In the so- called chill casting process, the liquid aluminum is fed at high pressure into a
structure, together with corrosion and coating adhesion. During rotary bend- ing, impact and radial runout tests and other tests on the Porsche biaxial wheel test stand (ZWARP), the wheels must show that they meet all the relevant re- quirements. Only when the wheels have successfully passed all these tests are they approved for use on a Porsche.
Staying on track
There is a long tradition of wheel de- velopment at Porsche. In 1962, when Porsche began developing the 911 range, the engineers were looking for a very spe- cial wheel for the new model. They need- ed an alloy wheel with excellent proper- ties and a completely new look. As a result of their work on development pro- jects for the German army, the Porsche engineers already had experience of al- loy wheels. The track rollers of the tank running gear they had developed were made of forged aluminum. Therefore they decided to use the experience from this project. The 911 was the first car to have forged alloy wheels – the Fuchs wheels which are still popular today. But that was not the end of wheel development at Porsche, it was only the beginning. Many more high points were to come, as a glance at the history of Porsche wheels shows. Because of their light weight and high levels of stability, only alloy wheels are now used at Porsche, made mainly of aluminum.

Copyright Porsche Engineering Magazine 2009
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