Walk into any F1 team’s workshop and you’ll see carbon fiber (like in the monocoque, bodywork, and wings). But look a little closer, and you’ll see aluminum parts stacked atop workbenches. With teams spending £300 million a season, you would think they would use a more exotic material. In fact, they choose aluminum because it has properties that carbon fiber does not have.
It is clear that there are some cost-saving benefits to using aluminum, but that is only one reason carbon fiber is not used. Sure, a billet aluminum component would cost less than a carbon fiber one; however, if you are spending millions on development, it is not a huge cost-saving to try to lower costs a few thousand on parts. There are much more important engineering properties that make aluminum irreplaceable.
Consider suspension components. Wishbones and pushrods are designed to be stiff under normal loads but are still able to absorb sudden impacts. This happens when a driver clips a curb at 200 mph. Carbon fiber is able to handle predictable loads in one direction but an unexpected side load can make it fail catastrophically.
Aluminum bends but doesn’t break. This helps maintainers see stressed components without needing to inspect them too closely. A damaged component might still be able to get you back to the pits instead of finishing your race. In Formula 1, Aluminium 7075-T6 dominates suspension work. With a yield strength of around 500 megapascal, it performs similarly to a lot of steels whilst weighing 33% less. They part off solid billets for the wishbones, removing material in places deemed not needed from the stress analysis. This makes a part as light as one that is carbon fiber but is still more durable. Most people underestimate the role of inspection. Between practice sessions, components have to be checked for damage quickly Mechanic dampers practice components. With aluminum, scratches, cracks, or any other visual signs of damage are easily identified. With carbon fiber, you have to use sonic or x-ray testing to inspect for internal damage. This is nearly impossible to do between sessions.
The value of being able to examine and confirm a component’s integrity in a matter of minutes rather than hours greatly outweighs merely saving 200 grams. Speed in machining is also a factor. When regulations change, or a team discovers a performance advantage, they must quickly produce new components. Standard equipment can machine aluminum in just a few hours, while carbon fiber parts entail making molds, developing lay-up schedules, completing curing cycles, and more. If you discover a tenths of a second improvement in suspension geometry on Friday morning, you want those parts on the car for qualifying on Saturday—not three weeks later. Thermal properties are another factor. Aluminum is a good conductor of heat. In applications like brake calipers and suspension uprights that need to lose heat, that sounds like a disadvantage. but, Aluminum can be machined in hours using standard equipment. Carbon fiber components require molds to be made, layout schedules to be developed, and curing cycles to be completed. If you find a tenths of a second in suspension geometry on Friday morning, you want those parts on the car for qualifying on Saturday, not three weeks later. Insulating carbon fiber helps keep heat away from the driver in the monocoque but is terrible when you need to move heat away from brake components. Aluminum also repairs and modifies differently. If a part is made of aluminum, and is damaged, it can sometimes be repaired by machining the damaged part and welding in new pieces. With carbon fiber it’s bin it, and replace the whole thing.
When a team has a small amount of extra parts, and has a crash on Saturday morning, the ability to repair is made easier than the ability to replace, and that can mean the difference between making the grid and watching from the garage. The argument for fasteners is interesting as well. When bolting together carbon fiber components, the bolts can crush the carbon, and are required to use metal inserts. These inserts add weight and complexity. With aluminum, you can do far simpler things than metal inserts, and then you can through. The weight of all those metal inserts in a carbon fiber heavy design adds up surprisingly a lot. It is not because they are trying to that teams use aluminum.
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