Investor Engineering Discussions

[scaesare]

Yeah, I wasn't trying to imply you were saying they were centered. I posted here to give my thought in support and tagged you both since you were the main discussors.

Gotcha.. given that you tagged two posters with opposing views, it wasn't clear if was a post in support of one viewpoint, a rebuttal of another, etc... given you were making a statement that was already stated...

Nonetheless, just a context issue... all good. And incidentally I agree, that looks right to me...

 

[GhostSkater]

You guys might be right, I swear Tesla gives us the worst angles on this short clips to screw us over lol

 

[mongo]

You guys might be right, I swear Tesla gives us the worst angles on this short clips to screw us over lol

I hear ya, not much multiview in that video.
Cool to see semi drive unit though.

 

[mongo]

LK Machinery is introducing their 16k ton Die-casting machine either today or tomorrow (unsure of what timezone Edward Tse is in). What could a 16k ton be used for? Who do you think would make use of it?

LK 16,000T Die Casting Showcase | Edward Tse posted on the topic | LinkedIn

Seeing is Believing! ð Tomorrow, we're taking the wraps off the LK 16,000T Die Casting Machine, and you won't believe your eyes! Witness the future ofâ¦

www.linkedin.com

View attachment 985133

Useful for making parts twice with about double the width (or length) as current presses.
Looking forward to seeing if they needed to go with 6 tie rods or were able to use 4 and thicker platens.

 

[mongo]

My question is once you go from 8T to 16T the molten secret sauce injection process has to still happen in ~2 seconds. Whatever the time is. Now, my uneducated guess is that this is getting more difficult to a extreme. Injecting 1x vs 2x of alloy at this volume and get same quality must be hard.

Any expert comments about this?

Using an injector with twice the area keeps velocity the same. Die needs more runners to get the metal when you want it which can mean lower final part percentage by weight.
The 8k and 9k presses have over double the sleeve size of 5.5k and 6.1k versions for double the max shot mass.

 

[GOVA]

Using an injector with twice the area keeps velocity the same. Die needs more runners to get the metal when you want it which can mean lower final part percentage by weight.
The 8k and 9k presses have over double the sleeve size of 5.5k and 6.1k versions for double the max shot mass.

So... not that difficult to go 2x? Cooling/porosity still happy? I am just trying to see how far can they go.

 

[mongo]

Two points of injectability? So two cauldrons of soup being dumped at the same time.

Only if you want a mating line.
[Which may happen anyway for parts with voids]

 

[mongo]

So... not that difficult to go 2x? Cooling/porosity still happy? I am just trying to see how far can they go.

My understanding is they pull a vacuum before injection, so porosity shouldn't be an issue. Cooling during flow may be an issue, but die temperature can help with that (potentially at the expense of cycle time).

 

[Krugerrand]

Only if you want a mating line.
[Which may happen anyway for parts with voids]

Possible. Or essentially pour it into the same point and let it flow to the ‘ends’.

The point being, no new technology required for a twice size casting just some creativity.

 

[MC3OZ]

I can't see how a single piece bottom casting works well with the unboxed process.

With 3 separate bottom pieces, the operator density ix 3 X 4 = 12.

With a single bottom piece the operator density is 4, + 4 = 8 (still 2 piece with the battery pack being 1 piece), to go higher than that operators need to step into the hole for the battery pack...

I am not doubting that large castings might be done, just wondering what part(s) of a compact Gen3 model would be cast.

 

[mongo]

I can't see how a single piece bottom casting works well with the unboxed process.

With 3 separate bottom pieces, the operator density ix 3 X 4 = 12.

With a single bottom piece the operator density is 4, + 4 = 8 (still 2 piece with the battery pack being 1 piece), to go higher than that operators need to step into the hole for the battery pack...

I am not doubting that large castings might be done, just wondering what part(s) of a compact Gen3 model would be cast.

If instrument panel is one module, it ccould be fastened at sides and from frunk, no interior access needed.
Rear seat needs structural pack installed first.
What is left that frame rails would interfere with?

Oh course; it could be that the 16,000 ton press just has a larger square die area, not rectangular.

 

[MC3OZ]

If instrument panel is one module, it ccould be fastened at sides and from frunk, no interior access needed.
Rear seat needs structural pack installed first.
What is left that frame rails would interfere with?

Oh course; it could be that the 16,000 ton press just has a larger square die area, not rectangular.

I might be taking the Investor Day Gen3 presentation too literally..

Essentially it showed 4 operators assembling things on each of :-

• Front Casting
• Rear Casting
• Structural pack.

If some Gen3 cars are smaller, narrower 2 seater cars, then reaching over the cast bottom to install things might not be difficult.

However, I also like the idea of stretching a 2-seater into a 4-seater via a longer structural battery pack.

What do you see as the major cost savings from a single large bottom casting compared to 2 separate front and rear castings?

IMO it possibly reduces weight, some additional parts (frame rails), and perhaps a few production line steps.

The trade-off is larger casting machines probably cost more, but the number of casting machines required is halved.

For run-rate, my hunch is smaller machines might be slightly faster...

While it might be around "break even" or perhaps a few hundred dollars per car, I can't see why there would be major cost savings..

All of the robots to build the Unibody frame (sides/roof) are still needed if it is built the same way...

 

[Buckminster]

https://twitter.com/x/status/1717546774829613470

 

[mongo]

https://twitter.com/x/status/1717546774829613470

So it is mostly square, that reduces chances of full chassis casting.

 

[Buckminster]

Atoms of space almost made sense to me. Starts 27 mins in:

 

[Buckminster]

Analogue octovalve:

https://twitter.com/x/status/1719054571530793252

 

[Buckminster]

https://twitter.com/x/status/1719812287689523222

 

[MC3OZ]

Here is the full video from Sandy... well worth watching...

 

[mongo]

The speculation on end cooling is because recent pictures of the body make it more probable that the pack will be a single layer

For a single layer pack to achieve 500 miles of range, they either need more space for the cells, which bottom cooling delivers, or significantly more efficient than even the most optimistic predictions

It might seems that the cooling snakes add little space between cells, but it adds up

The downside is that even with the tabless electrode touching the bottom, a few papers shows that there is better cooling with side cooling due to higher surface area compared to bottom cooling, mostly due to the dichotomy of extracting heat from the cells, you need something that is a really good heat conductor but also good electrical insulator, the interface between cell and cooling device is the limitation, so more area helps a lot

The only downside of both papers is that if I'm not mistaken both assumes that the entire side of the cells is cooled (been a while since I've read them, linked bellow) and we know Tesla uses just a small section of the cell, so in that scenario cooling the bottom might win vs just part of the side

Sandy better get one really soon to open it up

Prediction of Thermal Issues for Larger Format 4680 Cylindrical Cells and Their Mitigation with Enhanced Current Collection
Impact of Current Collector Design and Cooling Topology on Fast Charging of Cylindrical Lithium-Ion Batteries

An optimal snake approach uses 1/6 of the side area (cells touch at 60 degrees).
Maximally:
23*23*pi = 529 pi for bottom area
2*23*pi*80/6 = 613 pi for side area
Of course, the further from the electrode interface, the lower the thermal conductivity.

Tesla does also have patent applications for nearly fully immersed cells.

 

[BioSehnsucht]

I'd think that as cells grow larger, single ended cooling becomes less usable if you expect high C rates. The temperature gradient becomes a bigger issue the further the cooling point gets from the far side, and single end (i.e. bottom) cooling is going to be incredibly worse than side cooling as the cells get larger, unless they end up wider than they are tall somehow.

This might have been feasible with a 16850 or 2170 cell that had single tab but I suspect 4680 in high performance applications it won't work.

Probably fine in storage and lower end vehicles however so we might see it in fit example the next gen vehicle, of supercharging speeds aren't a problem for it (i.e. lighter/smaller translating to smaller pack and less needed C rate for x% per y minutes goals - would be still lower kW speed than a 3/Y for example but might be similar "mph" charging rate), so if it's a significant cost savings and the effective charging speed is not greatly impacted, might see use.