Tesla intends to integrate the battery pack to the body structure of its future cars, and large cast parts are a crucial part of that idea. Tesla CEO Elon Musk said the company has commissioned the world's largest stamping machine. Eventually, it'll be used to make massive single-piece stampings for the front and rear of the chassis, while a battery pack filled with Tesla's new 4680 cells will make up the center section.
Elon Musk said Tesla developed a specific alloy to make that happen. This new aluminum alloy had to be very castable, high-strength, and not prone to retreat, which causes large castings to deform.
What Tesla is casting now at Fremont are the front and rear sections of its cars. That will be complemented by what we now call the battery pack. Considering it will be part of the car structure and hence not replaceable as current battery packs are, Tesla will probably have to name it as something else like a “structural battery.”
This new structural battery casing will not only provide the car with the energy it needs but also ensure its rigidity and safety. A lighter car can travel further and be more energy-efficient. Musk also said that the resulting structure is much stiffer than you would find in any current car, even if it were a convertible.
According to Musk, that will allow the car to have a 10 percent weight reduction, a range increase of up to 14 percent, and 370 fewer parts, which implies the manufacturing and production costs are much lower than the ones Tesla has nowadays.
There are some questions though - how would you replacing old or defective batteries? If the batteries are part of the car structure, you either get them to last as much as the car itself, or you have to get rid of the vehicle altogether if anything goes wrong with them.