The conventional wisdom is that Ferrari, due to its low production volumes and high-profile name, can do nearly anything technologically that it is inclined to do. So what is Ferrari doing? For one, it’s recently announced its commitment to building future production vehicles primarily out of aluminum—as in aluminum engines, transmissions, pedal assemblies, steering gear, suspension pieces, body panels, and even interior trim. And while Ferrari is no stranger to alluminio (for years it has used aluminum body panels on its production vehicles, not to mention aluminum-chassis racecars), the decision to develop production aluminum spaceframes is a significant change for the world’s most famous high-performance automaker.
|Ferrari is committed to building future production vehicles with aluminum spaceframes like the one in this 360 Modena.|
More Car, Less Weight. The newest Ferrari model, the 360 Modena, is the first iteration of this aluminum design philosophy. Luca Cordero di Montezemolo, chairman of Ferrari spa, explains that the decision to use aluminum “can be summed up in a single figure. Size for size, it allowed for something like a 34% reduction in vehicle weight with an obvious benefit in terms of performance and safety.”
That figure is derived vis-à-vis the previous F355 model, which used a steel spaceframe to carry aluminum body panels. But the meaning of the number necessitates some further explanation, as the 360 Modena is not just an F355 with a higher aluminum content. In response to customer demand for a roomier cockpit (it seems that even Ferrari can’t escape the golf bag test—in fact, one now fits behind the new car’s front seat), the 360 Modena’s interior grew by 45 mm in length and 50 mm in height. Wheelbase and track increased 150 mm and 155 mm compared to the F355, as well. This means that the actual weight reduction, when the two overall chassis are not adjusted for size, is only about 28%.
Design and Manufacture According to Carlo Carcioffi, Ferrari design engineer, the 360 Modena is made with approximately 40% aluminum, as compared to the F355 with only 14%. But despite the fact that the 360 Modena is “thinner,” Carcioffi points out that it carries a 42% increase in flexional stiffness and a 44% increase in torsional stiffness. Part of this increase can be attributed to design. “We made as many items as possible multifunctional, which reduced the actual number of bodyshell components by 35%,” explains Carcioffi.
The aluminum spaceframe is built from a combination of both sand and vacuum die castings joined to extrusions with a combination of corrosion-protected steel screws, rivets and MIG welding. (47% of the aluminum in the car are extrusions, 33% are castings, 17% is sheet aluminum; the other 3% is joining material.) The vast majority of the extrusions are straight pieces; however, stretch bending, rotary drawing and press forming are also employed.
“Castings are expensive,” Carcioffi says. This makes it crucial to design the best possible parts. For example, a single shock tower casting will replace 10 suspension mounting parts, thus reducing complexity and improving the precision with which the suspension can be mounted. To achieve this precision Ferrari employs a process by which the castings are actually milled after the spaceframe is assembled.
While Carcioffi admits that undoubtedly the aluminum spaceframe of the 360 Modena costs more than the steel one of the F355, this shouldn’t be thought of as a negative. On the contrary, he believes that in the creation of the next generation of aluminum spaceframe, they should be able to cut the cost difference in half, just based on what they’ve learned this time around.
Much of Ferrari’s learning has come as a result of their partnership with American Alcoa. (Alcoa having gained considerable know-how while working with Volkswagen on the “all-aluminum” Audi A-8.) For the 360 Modena project, Alcoa was involved in developing some of the aluminum manufacturing technology, and it is the supplier of vacuum castings and sheet aluminum. Carcioffi says that one of the biggest manufacturing challenges that they faced was a porosity difference in some castings that was causing bad welds. By improving internal quality control to produce better castings, this problem was solved.
Alcoa also did finite element analysis modeling of all the critical joints in the spaceframe. These were modeled separately and then incorporated into the overall model of the chassis. One development that came out of this analysis was the decision to use the position of the transmission to act as a crash-absorber, rather than adding size and weight to the spaceframe.
Buona Fortuna. Even given their relatively small production volume (3,775 cars in 1999), Ferrari’s commitment to developing aluminum design and manufacturing technology should be beneficial to the auto industry at large. If costs go down and the aluminum infrastructure increases, the materials options available, even to mass producers, will be more varied. In turn, the world will undoubtedly continue to get even better Ferraris.