I really, really, really did not like this post. I found it to be riddled with bad assumptions, questionable unsupported claims, and critical omissions. I don't think any of the core arguments survive close scrutiny.
Moreover, I took serious issue with the tone throughout. The first half hand-waves some seriously questionable claims into existence with strong confidence, while the second half opines that everyone who ever thought otherwise is some combination of sycophantic, incurious, brainwashed, or an idiot. I would have appreciated more intellectual humility.
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My read is that this post totally whiffed on the entire subject of die casting cost savings.
The chassis of cars is a relatively small fraction of their cost. The cost of aluminum die casting and stamped steel is, on Tesla's scale, similar. Yet, there were so many articles saying gigacasting was a major advantage of Tesla over other companies.
To be clear: the cost savings argument for die casting is little to do with the cost of the chassis itself, it's mostly an argument about the cost of body assembly.
In an automotive assembly line one of the most labor-intensive, challenging, and expensive steps is the "body shop," where a car's structural components are assembled into a "body in white." Die casting saves time and money by reducing the number of welds, bolts, etc. required to go from components to body. It also cuts down on total weight, waste material from manufacturing a larger number of components, and the number of steps one can introduce tolerance errors.
Here is an example from the Model 3. Switching from traditional assembly to die casting cuts out 169 separate metal parts and 1600 welds. Those costs add up! Look at the difference in estimated variable costs.
in short, your claim: "The cost of aluminum die casting and stamped steel is, on Tesla's scale, similar" both seems to miss the entire point and run against literally everything I have seen written about this. You need citations for this claim, I am not going to take your word for it.
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The price thing alone seems like a post invalidating miss, but I was pretty alarmed by the sheer number of other strong assertions made with weak or no supporting evidence. Some of these seemed obviously wrong.
Tesla has been widely criticized for stuff not fitting together properly on the car body. My understanding is that the biggest reason for that is their large aluminum castings being slightly warped.
Tesla's panel gap issues predate the giga press by like a decade and has always been attributed to wide tolerances for all parts and lazy QA (de-prioritized in favor of R&D). I have absolutely no idea how you got to this "understanding." Citation please?
As for voids, they can create weak points; I think they were the reason the cybertruck hitch broke off in this test.
Or the geometry of the frame was insufficiently optimized for vertical shear. I do not understand how you reached this conclusion.
BYD is still welding stamped steel sheets together, and that's why it can't compete on price with Tesla. Hold on, it seems...BYD prices are actually lower than Tesla's? Much lower?
Price alone doesn't really say anything about the giga press. Perhaps BYD's efficiency could be explained by some of the other few thousand things that go into making a car? What about all the other stamped steel chassis companies BYD is way more efficient than?
Also, production costs are the actual thing that matter for this argument, not price. Tesla has 6x the profit per car of BYD which obviously factors into the higher prices.
Oh, and Tesla is no longer planning single unitary castings for future vehicles?
This is a bit misleading. Tesla doesn't currently do unitary castings, so this is a suspension of future R&D not changing what they currently do. Importantly, this means they will keep giga casting their chassis for the foreseeable future.
Money is a factor, of course; PR agencies drive a lot of the articles in media. I assume Tesla pays some PR firms and people there presumably decided to push the Giga Press.
You should stop assuming! Tesla spent essentially nothing on marketing until 2023, well after this assumed PR would be taking place. By nothing I mean that the estimate for their marketing spend in 2022 (literally all marketing to include PR if there was any at all) was $175k.
in short, your claim: "The cost of aluminum die casting and stamped steel is, on Tesla's scale, similar" both seems to miss the entire point and run against literally everything I have seen written about this. You need citations for this claim, I am not going to take your word for it.
OK, here's a citation then: https://www.automotivemanufacturingsolutions.com/casting/forging/megacasting-a-chance-to-rethink-body-manufacturing/42721.article
Here I would be careful since investments, especially in a particular model generation of welding robots, are depreciated. For forming processes, the depreciation can even extend over three or four model generations. This technological write-off – bear in mind that this is not tax-related – runs over a timeframe of 30 years. For the OEMs that are already using these machines for existing vehicle generations, the use of the new technology makes no sense. On the other hand, thanks to its greenfield approach, Tesla can save itself these typical investments in shell-type construction. In a brownfield, it would be operationally nonsensical not to keep using long depreciated machinery. So, in this situation, I would not support the 20-30% cost savings that were cited.
With die casting, one important aspect is that there is a noticeable reduction in the service life of the die-casting moulds. Due to so-called thermal shock, the rule of thumb is that a die-casting mould is good for 100,000-150,000 shots. By contrast, one forming tool is used to make 5m-6m parts. So, we are talking about a factor of 20 to 30. There is quite clearly a limited volume range for which the casting-intensive solution would be appropriate. To me, aluminium casting holds little appeal for very small and very large volumes. Especially for mass production in the millions, you would need about six or seven of these expensive die-casting moulds. We estimate that the die-casting form for the single part, rear-end of a Tesla would weigh about 80-100 tonnes. This translates to huge costs for handling and the peripheral equipment, in the form of cranes, for example. Die-casting moulds also pose technological obstacles and hazards. The leakage of melted material is cited as one example. The risks of not even being able to operate in some situations are not negligible.
Or the geometry of the frame was insufficiently optimized for vertical shear. I do not understand how you reached this conclusion.
No. If aluminum doesn't have weak points, it stretches/bends before breaking. The Cybertruck hitch broke off cleanly without stretching. Therefore there was a weak point.
By nothing I mean that the estimate for their marketing spend in 2022 (literally all marketing to include PR if there was any at all) was $175k.
I'm skeptical of that. PR firms don't report to Vivvix.
I'm interested in having Musk-company articles on LessWrong if it can be done while preserving LessWrong norms. I'm a lot less interested in it if it means bringing in sarcasm, name calling, and ungrounded motive-speculation.
Cool blog post on the history of the large forging press: https://www.construction-physics.com/p/how-to-build-a-50000-ton-forging?utm_campaign=email-half-post&r=ym929&utm_source=substack&utm_medium=email
Construction Physics has a very different take on the economics of the Giga-press.
Tesla was the first car manufacturer to adopt large castings, but the savings were so significant — an estimated 20 to 40% reduction in the cost of a car body — that they’re being adopted by many other car manufacturers, particularly Chinese ones. Large, complex castings have been described as a key tool for not only reducing cost but also good EV charging performance.
I think Construction Physics is usually pretty good. In this case my guess is that @bhauth has looked into this more deeply so I trust this post a bit more.
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1Let's see...
savings were so significant — an estimated 20 to 40% reduction in the cost of a car body
I think that should be "car frame" - the "body" includes things like doors. Anyway, I'm sure that was estimated by some people, but...
that they’re being adopted by many other car manufacturers, particularly Chinese ones
Not really? Several major carmakers were considering using the same approach after Tesla did that, but last I heard they'd backed off. That's how big companies tend to work: executives see a competitor or startup doing something, and then they get some people (internal engineers, consultants, etc) to evaluate if they should be doing the same thing. Doesn't mean they actually will.
good EV charging performance
To be clear, I'm not saying aluminum casting (or forging) is useless; there's a reason people make a lot of aluminum. Battery compartments are one of the better places to use it, because the high thermal conductivity is relevant. But that's different than casting large frame pieces or an entire frame.
As for very large presses for aluminum, those Heavy Press Program ones are several times bigger than Tesla's, and I think friction stir welding progress making it possible to weld aluminum alloys without making weak points might have been why people didn't keep going bigger - combined with even larger components being hard to transport, of course.
When magazines talked about, say, "microservices" or "the cloud" being the future, it actually made them happen. There are enough executives that are gullible or just want to be given something to talk about and work on that it established an environment where everyone wanted to get "microservices" or whatever on their resume for future job requirements, and it was self-sustaining.
Is the claim here that cloud computing and microservice architectures are less efficient and a mistake?
The claim was that the decision to go to cloud computing and microservice architectures wasn't based on whether they were a good idea.
But also, yes, I think they're used in many cases where they're less efficient and a mistake. The main argument for cloud stuff is that it saves dev time, but that's a poor argument for moving from a working system to AWS. And microservices are mostly a solution to institutional/management problems, not technical ones.
And microservices are mostly a solution to institutional/management problems, not technical ones.
So this is interesting in context, because management and coordination problems are problems! But they're problems where the distinction between “people think this is a good idea” and “this is actually a good idea” is more bidirectionally porous than the kinds of problems that have more clearly objective solutions. In fact the whole deal with “Worse is Better” is substantially based on observing that if people gravitate toward something, that tends to change the landscape to make it a better idea, even if it didn't look like that to start with, because there'll be a broader selection of support artifacts and it'll be easier to work with other people.
One might expect an engineering discipline to be more malleable to this when social factors are more constraining than impersonal physical/computational ones. In software engineering, I think this is true across large swaths of business software, but not necessarily in specialized areas. In mechanical engineering or manufacturing, closer to the primary focus of the original post, I would expect impersonal physical reality to push back much harder.
A separate result of this model would be that things become more fashion-based on average as humanity's aggregate power over impersonal constraints increases, much like positional goods becoming more relatively prominent as basic material needs become easier to meet.
1Well, in the specific case of microservices, I think the main problem being solved is not allowing people on other teams to modify your part of the code.
In theory, people could just not do that. It's kind of like how private variables in Java are considered important, even though sometimes there's a good reason to change them and theoretically you could just use variable names / comments / documentation to indicate which variables are normally meant to be changed. There's a tradeoff between people messing with stuff they shouldn't and inability to do things because you rely on other groups. You could break a monolithic project into multiple git repos instead, but I guess that psychologically feels worse.
I haven't worked in an organization that uses microservices extensively, but what I hear from people who use them goes far beyond visibility constraints. As an example, allowing groups to perform deployment cycles without synchronizing seems to be a motivation that's harder to solve by having independently updated parts of a build-level monolith—not impossible, because you could set up to propagate full rebuilds somehow and so forth, but more awkward. Either way, as you probably know, “in theory, people could just … but” is a primary motivator behind all kinds of socially- or psychologically-centered design.
That said, getting into too much detail on microservices feels like it'd get off topic, because your central example of the Giga Press is in a domain where the object-level manufacturing issues of metal properties and such should have a lot more impact. But to circle around, now I'm wondering: does the ongoing “software eating the world” trend come along with a side of “software business culture eating into other business cultures”? In the specific case of Tesla, there's a more specific vector for this, because Elon Musk began his career during the original dot-com era and could have carried associated memes to Tesla. Are management and media associated with more physical industries being primed this way elsewhere? Or is this just, as they say, Elon Musk being Elon Musk, and (as I think you suggested in the original post) the media results more caused by the distortion of celebrity and PR than by subtler/deeper dysfunctions?
Hmm, I think there are a few reasons for software people getting into other industries over vice-versa:
- Software has been very profitable, largely because of how ad-based the US economy has become. So a lot of the available money is from the software side.
- Because code scales and software doesn't require as much capital investment as heavy industry, there are more wealthy founders who did some code themselves than wealthy founders who do, say, chemical engineering themselves. That means you have wealthy people who a) like starting companies and b) are engineering-oriented.
- American companies seem to have more of a competitive advantage vs Japan/China for code than manufacturing. Note that I said companies; Japan actually makes lots of high-quality open-source software.
I don't think that's the sophisticated argument for switching your in house app to the cloud. There's a recognition that because it's more efficient for developers, more and more talent will learn to use and infrastructure will be built on top of cloud solutions.
Which means your organization risks being bottlenecked on talent and infrastructure if you fall too far behind the adoption curve.
"Everyone is going to switch to cloud stuff" means that, in the short term, there will be a shortage of cloud people and an excess of non-cloud people.
Your argument is for hiring in a long-term future where the non-cloud people retired or forgot how to do their thing, but we know that's not what US executives were thinking because they don't think that long-term due to the incentives they face.
And it certainly doesn't explain some groups of companies switching to cloud stuff together and then switching back together later.
we know that's not what US executives were thinking because they don't think that long-term due to the incentives they face
The story of "they're doing something that's bad in the short term, but good in the long term, but only accidentally they're actually trying to do something good in the short term but failing" seems suspicious.
I know that the CEOs I know do plan in the long term.
I also know that the many of the worlds most famous consumer brands (Apple, Amazon. Tesla) have valuations that only make sense because people trust the CEOs to prioritize the long term and those future earnings are priced in.
And I also know that if you look at the spending budget of many of the top consumer tech companies, and the amount spent on longterm R&D and moon shots, it sure looks like they are spending on the long term.
Loving the discussion of casting vs stamping! Very interesting info, and you’ve explained it clearly :)
As for voids, they can create weak points; I think they were the reason the cybertruck hitch broke off in this test.
Though as I understand it that test was after a load of other tests. Perhaps relevant.
Yes, it's certainly relevant - any fatigue aluminum has is relevant, because it doesn't have a fatigue threshold like steel or carbon fiber. But fatigue is normally a bigger problem over years, and that was a practically-new cybertruck. And aluminum is supposed to bend/stretch; when it breaks like that, it's generally because there's a weak point from eg a weld.
What concerns me is the failure of institutions and cultural systems.
How do you know these ‘systems’ failed?
Don’t you need to be aware of the true internal reality of those cultures (of captains of industry, high ranking officials, literal geniuses, etc…) in the first place, in order to make an assessment?
If your talking about mass culture, or being generous, the 95th to 99.9th percentile intellectual cultures of the upper middle class, then it seems a bit irrelevant whether this engineering analysis ‘succeeded’ or ‘failed’.
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1I dont think this is a good take.
The Cybertruck does not break on that pull. It breaks on this one: 0:27
I dont think this is a good take.
The Cybertruck does not break on that pull. It breaks on this one: 0:27
Your comment isn't worded well: what isn't a good take, exactly?
Then you imply that the truck breaks on a different pull, and link to it going over concrete pipes. I'm assuming you meant it cracked from that impact so it broke on the pull. That's wrong, look closely, please don't just blindly repeat something you saw on a forum somewhere without even linking to it.
Finally, aluminum isn't supposed to break like that, it's supposed to be ductile. That kind of failure indicates some sort of weak point being present.
the giga press
Tesla decided to use large aluminum castings ("gigacastings") for the frame of many of its vehicles, including the Model Y and Cybertruck. This approach and the "Giga Press" used for it have been praised by many articles and youtube videos, repeatedly called revolutionary and a key advantage.
Most cars today are made by stamping steel sheets and spot welding them together with robotic arms. Here's video of a Honda factory. But that's outdated: gigacasting is the future! BYD is still welding stamped steel sheets together, and that's why it can't compete on price with Tesla. Hold on, it seems...BYD prices are actually lower than Tesla's? Much lower? Oh, and Tesla is no longer planning single unitary castings for future vehicles?
I remember reading analysis from a couple people with car manufacturing experience, concluding that unitary cast aluminum bodies could have a cost advantage for certain production numbers, like 200k cars, but dies for casting wear out sooner than dies for stamping steel, and as soon as you need to replace them the cost advantage is gone. Also, robotic arms are flexible and stamped panels can be used for multiple car models, and if you already have robots and panels you can use from discontinued car models, the cost advantage is gone. But Tesla was expanding so they didn't have available robots already. So using aluminum casting would probably be slightly more expensive, but not make a big difference.
"That seems reasonable", I said to myself, "ふむふむ". And I previously pointed that out, eg here. But things are actually worse than that.
aluminum die casting
Die casting of aluminum involves injecting liquid aluminum into a die and letting it cool. Liquid aluminum is less dense than solid aluminum, and aluminum being cast doesn't all solidify at the same time. Bigger castings have aluminum flowing over larger distances. The larger the casting, the less evenly the aluminum cools: there's more space for temperature differences in the die, and the aluminum cools as it's injected.
As a result, bigger castings have more problems with warping and voids. Also, a bigger casting with the same curvature from warping has bigger position changes.
Tesla has been widely criticized for stuff not fitting together properly on the car body. My understanding is that the biggest reason for that is their large aluminum castings being slightly warped.
As for voids, they can create weak points; I think they were the reason the cybertruck hitch broke off in this test. Defects from casting are the only explanation for that cast aluminum breaking apart that way. If you want to inject more aluminum as solidification and shrinkage happens, the distance it has to travel is proportional to casting size - unless you use multi-point injection, which Tesla doesn't, and that has its own challenges.
Somehow I thought Tesla would have only moved to its "Giga Press" after adequately dealing with those issues, but that was silly of me.
One approach being worked on to mitigate warping of large aluminum castings is "rheocasting", where a slurry of solid aluminum in liquid aluminum is injected, reducing the shrinkage from cooling. But that's obviously more viscous and thus requires higher injection pressures which requires high die pressures.
aluminum vs steel
Back when aluminum established its reputation as "the lightweight higher-performance alternative" to steel, 300 MPa was considered a typical (tensile yield) strength for steel.
Typical cast aluminum can almost match that, and high-performance aluminum for aircraft can be >700 MPa. Obviously there are reasons it's not always used: high-strength aluminum requires some more-expensive elements and careful heat-treatment. Any hot welds will ruin the heat-treatment and thus be weaker.
But now, 1000+ MPa steel is common and used in many cars, and it's possible to get higher strengths than that. Aluminum alloys have had much less progress. I suppose that's because a lot of research went into aircraft materials in the past, and because steels are overall more complex.
Aluminum also has worse heat & fatigue resistance than steel, but it resists corrosion as well as stainless steel (which is weaker and more expensive than normal steel). Steel exposed to water needs to be painted. On the other hand, aluminum is more expensive, and most people want it painted anyway.
When a car is made from stamped steel sheets welded together, if one area gets dented, it's sometimes possible to cut that part off and weld on a replacement. People don't do such repairs as much as they used to, due to the relative cost of manufacturing vs labor changing, and design changes that make repair harder, but it's at least a theoretical advantage.
Aluminum is less dense than steel, which at the same strength-weight ratio increases bending strength, but casting also can't produce thin walls or the complex ridge patterns that stamped steel can. Aluminum is also harder to weld, and die casting can't produce hollow tubes like stamp + weld can.
this shouldn't be a thing
The chassis of cars is a relatively small fraction of their cost. The cost of aluminum die casting and stamped steel is, on Tesla's scale, similar. Yet, there were so many articles saying gigacasting was a major advantage of Tesla over other companies.
I don't really care if Tesla cars have some panel gaps or some cars cost 3% more to make. If you're interested in minor improvements to car manufacturing, my friends have thought of more interesting ones, such as:
As for how my car-manufacturing-related predictions have gone so far, some years back, I remember being optimistic about the practicality of:
So, the reason I'm writing about this isn't because of how much I care about die casting vs stamping. What concerns me is the failure of institutions and cultural systems.
When magazines talked about, say, "microservices" or "the cloud" being the future, it actually made them happen. There are enough executives that are gullible or just want to be given something to talk about and work on that it established an environment where everyone wanted to get "microservices" or whatever on their resume for future job requirements, and it was self-sustaining. Gigacasting isn't at that self-sustaining point, but it's another example of how shallow the analysis behind the decision-making processes of American businesses is.
What's worse is that something actually good could've gone in that cultural space. MIT press releases full of BS, Forbes 30 lists full of scammers, stupid TED talks...these things occupy the spaces that actually-good ideas needed to succeed.
why was this a thing
Why were there so many articles that wrongly decided the Giga Press was of paramount importance and wrongly assessed its relative advantages vs existing systems? I think there were a few reasons.
Money is a factor, of course; PR agencies drive a lot of the articles in media. I assume Tesla pays some PR firms and people there presumably decided to push the Giga Press.
There are many fans of Tesla in general and Elon Musk personally. They want to see positive news about Tesla - especially news about Tesla pushing technology forwards, because that's what they like about Elon. In the current American economy, where the limiting factor for a lot of investment is the legibility of technical expertise to investment managers, someone like Elon provides what's missing.
The theory behind managers specializing in "management in general" was that business executives don't need technical understanding because they can get expert advisors, but it doesn't work. Elon actually provides some examples of why: there were engineers at SpaceX and Tesla who knew why the Hyperloop concept was flawed and the Giga Press would be somewhat worse, but did they go tell Elon that? I don't think so. Elon, despite understanding engineering much better than the median US executive, wasn't able to cut through the sycophancy and BS.
Even having the decisions made by people with PhDs doesn't always work. I've talked to a number of business executives with scientific PhDs, and I'd sometimes look up their thesis and figure I'd make some brief but intelligent comment to show a basic level of scientific understanding. Some of them forgot everything about the topic they studied, and some of them...in retrospect, I think they had their thesis ghostwritten.