2.Tesla Model Y body shell analysis prior to release (6th Feb 2020)

The Tesla model Y is being built using some advanced manufacturing techniques - including the use of casting to form part of the body structure.

Previously Tesla has been using mainly hydraulic presses to form body components from aluminium blanks for the model S and X. Robots are used to move the blank into the press and then over 1000 tons of force may be applied to force the blank into shape between a pair of dies.

For the model 3 Tesla moved to more steel components, but kept some aluminium as well. If we look at the body shell of the model 3 we can see these  stamped components fitted together into the body shell. 

Images from the model 3 repair manual tell us where ultra high strength steel is used - in red, high strenth steel in yellow, where mild steel is used in blue and aluminium in silver.

Note also how the sides of the model 3 are constructed from three separate pressings - the outer frame of mild steel, a middle core frame of ultra high strength steel and  an inner frame also of ultra high strength steel.

Now if we look at the rear floor of the Model Y we can see structures typical of casting. Structures that cannot be formed by pressing.  I have highlighted a large single casting in blue. We can see a three dimensional web of metal. This is much stronger and stiffer than can be achieved with a stamped component, and a single casting like this is formed in a single process. If we look at this casting from the side ( an image published by inside evs dot com, ) we can see that many bolt attachment points are cast into this as part of the casting. They don't have to be added to a pressing as a series of further operations.

We can also look at this casting from the front of the vehicle to see how much has been integrated here.

The casting has forward projections to support the sills, and vertical projections to support the side panels, as well as projections to the rear on each side..

If we look at the front of the car we can also see differences compared with the pressing used in the model 3. The anchor points for suspension, motors and steering are quite a complex structure and a casting here would result in a big reduction in manufacturing complexity. Making these a single casting that included the front bulkhead would be another huge simplification of the manufacturing process. But the images that we have don't have enough detail to confirm that this has been done.

The evidence that we have doesn't  show details that we would expect from castings on the door frames and sills, so I think these are still pressed components, and made of ultra high strength steel.

What we can see on the production line is that the reinforcement of the roof edge frame ends just before the front pillars. If the roof frame was cast I would expect this component to join with the front casting, or be the middle frame of ultra high strength steel that includes the front pillar.

We can also see from the production line that the outer shell that forms the side of the model Y is a pressed component. Inside this is another component that gives the side of the car more strength and is probably also pressed, and ultra high strength steel.

Other components of the model Y appear to be identical to those of the model 3 - and most likely to be the same pressed components - such as the floor over the battery. These could be replaced by another casting in the future. A casting would make this stiffer and stronger.

I have no doubt that Tesla will steadily move to increase the proportion of the body structure that is cast. Increasing both the size of the castings and their complexity.

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