How to build a 50k ton forging press
construction-physics.com
construction-physics.com
This is a super underappreciated fact! It's often repeated that forging is just stronger, but just squishing steel does NOT make it stronger. Forging a part is so much more than just smashing it into a shape.
Steel cable is made of pretty ordinary steel which is stretched 100s of times its original length. That process alone makes it 2-4x stronger in that direction. You stretch steel and it gets stronger in that direction.
Do you see how complicated that optimization process becomes? The process steps are not just trying to take it to the final shape. Your piston rod needs to be strong lengthwise, so you actually want to start with a short fat ingot and stretch it out instead of one that is near-final size.
Think of making an I-beam. You could hammer out the middle, making it thinner. That would give you a bit of strength there but very little on the edges. If you instead pull the edges out, you create a long continuous stretch that will be very strong against bending. Where, how, and in what order you stretch makes all the difference. You may want to leave extra material and cut it off later, so that your grains are all oriented together instead of tapering to a point.
For any moderately complex part, this process is as complicated as modern engineering problems. With poor steel you genuinely need to understand how to foster and bring out those continuous lines or your corkscrew will unwind like playdough. Blacksmiths had a legitimately intellectual job back in the day!
ACOUP noted that blacksmiths might be assisted by unskilled laborers, strikers, who had the actual job of lifting the hammer and hitting the object with it.
Make gracious assumptions.
Digging ditches generally sucks, same as I imagine being a striker, but most anyone can do it (until their body gives out, anyway, which in some cases is 'immediately').
The only question is whether someone will pay you for doing the fancy skill/science tricks or not.
Both of those points are untrue. Strikers are unskilled labor and in general are not learning how to forge. The smith shows where he wants the hammer to fall, and they let it fall there.
https://acoup.blog/2020/10/02/collections-iron-how-did-they-...
> Things were worse for the many strikers and other laborers who were essentially unskilled hired hands or even enslaved laborers (given their depiction in artwork, it seems likely many ancient strikers were slaves) of much lower status and who could not expect to be trained into blacksmiths themselves some day. While some strikers were probably apprentices in training, it is quite clear that not all of them were! These workers would also have been far less richly paid; indeed, the entire point of strikers was to have laborers who could be paid very little but still amplify the production ability of the blacksmith himself.
(emphasis original)
Sure, it takes a ton of muscle, but you can quickly screw up a piece by repeatedly beating the hell out of it.
Now I wonder if that is how these "magic cut" wasabi and ginger sachets work.
Guess I've got some googling to do.
PE = polyethylene. The most popular plastic on this planet.
HDPE = high-density polyethylene. One of the most common plastics. Milk jugs, glue bottles, etc.
Stick some UHMW tape on anything that needs to slide easier. Its surface is quite slippery
all the polyethylenes are relatively inert, because polyethylenes are in some sense just heavy paraffins. paraffin is germanized latin for 'relatively inert'
Some Nalgene's are polycarbonate, like those commonly drunk from. But not all, some are HDPE[0,1,2].
Some are Polypropylene co-polymer[3] but those are more for specialist things I guess.
[0] https://ultralightoutdoorgear.co.uk/ultralite-1-litre-wide-m... [1] https://www.cotswoldoutdoor.com/p/nalgene-hdpe-125ml-wide-mo... [2] https://www.elitemountainsupplies.co.uk/camping-trekking-c4/... [3] https://www.thelabwarehouse.com/products/bottle-nalgene-ppco...
just squishing steel does actually make it stronger, because it increases the number of dislocations in its crystal structure. smaller grains mean higher strength even without the variable grain direction. also, peening, which is not exactly the same as forging but is also just squishing steel, can give you higher strength for a third reason: areas with residual compressive stress can't initiate cracks until you overcome that stress, which increases strength. even more, though, it increases fatigue resistance
>"Can you forge metals in a highly controlled and directed magnetic field where you can orient the grain/alignment of atoms/fields in whatever direction you want. Further, if true, what happens when you make damascus from varying plated that have particular alignments/grains - and what are the features of this material?
This is how you make magnets. "Soft" ferromagnets have small, round grains that rotate to reinforce outside fields. "Hard" ferromagnets have permanent fields of their own and long grains that can't reorient.
Forging with a field has a very low impact on the material properties because of how weak a magnetic field is compared to the forces moving atoms- same reason steel loses its magnetic properties when it gets hot.
> what happens when you make damascus from varying plated that have particular alignments/grains
"Damascene" is the layered look most often made from acid etching sandwiched and forge-welded layers of different steels. Damascus is a single alloy for which the pattern is named.
Since in both cases the material is melted together, it's far too hot for any magnetic properties to have any impact.
Though I was thinking of super intense magnetic fields (like in CERN), however, Ill leave it to my Comic Book Science collection, then :-)
Then I started working in engineering, and I can't find any support for these claims. For sure when a steel bar is worked down to become wire for a steel rope, it cannot be pulled to an elongation of 100x increasing strength. A36 steel which is a basic structural steel has an elongation at break of 23% in a 2" gauge length [1]. In every rolling mill I've been in, there is a limited amount of reduction per pass through the mill, after which the metal needs to go for thermal treatment to be annealed to remove all the cold work. Every time you anneal the material, you completely resets the elongation (internal plastic strain) and strengthening due to work hardening. If they do too much reduction in one pass or at too low of a temperature, it cracks the material and makes it weaker.
For sheet metal, there is lore about the material being stronger in the rolling direction as that is the direction of grain flow. I have yet to find a source that can point to any large difference. In papers like this [2] there are claims of certain orientations of samples relative to rolling direction have different tensile properties, but when you look at the tensile charts, there is minimal difference. The yield strength in these charts isn't reported, but all three orientations look to yield at the same point. In this test the across the grain (90 degree to rolling direction) orientation had the highest tensile strength which is the opposite of the expectation of the forging "grain flow" promoters. But the magnitude of the difference isn't large, and is small relative to normal factors of safety in a reasonable design.
When designing automotive components, I've only ever seen forging methods selected for efficiency of production. If a part mostly fills the envelope of a bar or plate, it is cut from bar or plate in all cases. If there is a lot of void volume in the part, the calculation will be made to determine if the cost of developing forging tooling and development will get paid back in reduced material and machining cost. I have yet to see the dimensions of the part change with manufacturing method, which would be needed if the non-forged part was significantly weaker.
And finally, a lot of forged parts are subsequently heat treated. When heat treating steel all of the grains in the steel have to be destroyed and recrystallized. That is the mechanism by which heat treatment works. Depending on the exact process and part geometry, this process removes or reduces the grain flow in the finished parts.
Having said that, the claim of superiority of forging persists, and I'd love to see a technical reference that shows the magnitude of the change from someone who has plausibly actually tested the effect.
[1] https://matweb.com/search/DataSheet.aspx?MatGUID=d1844977c5c... [2] https://www.researchgate.net/publication/283447700_The_effec...
disclaimer: i don't have a relevant technical reference handy, and i'm far from an expert on the area, which is vast, and i recognize you know things i don't about it. still, i do spend a lot of time reading papers with metallurgical micrographs in them†, and i think i figured out the answer to your question many years ago, so i will explain my understanding
except for the part about grain orientation, anyway
> In every rolling mill I've been in, there is a limited amount of reduction per pass through the mill, after which the metal needs to go for thermal treatment to be annealed to remove all the cold work. Every time you anneal the material, you completely resets the elongation (internal plastic strain) and strengthening due to work hardening. If they do too much reduction in one pass or at too low of a temperature, it cracks the material and makes it weaker.
as i understand it, this is exactly right, but you say it as if it's contradictory. strain hardening increases the yield strength of metal (by making it yield). it can also change the tensile strength, but to a much smaller degree. when the metal can no longer handle stress by yielding, in particular by yielding in a way that produces further work hardening, so that the yield is distributed over the metal rather than being concentrated wherever it starts, it cracks. that's why strain hardening metal makes it more prone to cracking. in general, a given metal is more prone to cracking when you harden it, whether you harden it by cold forging, case hardening, or quenching. (peening is the exception; it inhibits crack initiation by a different method.)
https://en.wikipedia.org/wiki/Work_hardening has an overview that talks about how this phenomenon can be either desirable or undesirable
the change in yield strength from cold working can be quite large, a factor of 4 or so. it doesn't change the ultimate tensile strength much (or at all in the case of your wire rope), but there are a lot of cases where what you care about is the yield strength, not the uts, because if the part yields by more than a tiny amount, it is out of tolerance and has therefore failed
(with respect to a36 steel, elongation at break, and wire rope, this is a minor detail, but it's possible to elongate it somewhat more through rolling than you can through wire-drawing. but you are certainly correct that you cannot elongate it 100×, and wire rope is mostly made by drawing, not by rolling.)
there are different kinds of heat treatment, but the most common kind for steel involves a phase transition to austenite and back, which does indeed destroy the entire grain structure of the steel, losing any potential advantage of forging, precisely as you say. i'd think this would also be mostly true for hot-forging, where steel is forged while still austenitic; the relevant grain structure for strength will be the one that the steel acquires when it leaves the austenite phase. there are other kinds of heat treatment (more commonly used with things like aluminum) that don't involve fully recrystallizing the metal, and i would expect some grain structure to survive those
probably none of that is telling you anything you don't already know, but perhaps it's a different way of thinking about the things you know that explains the apparent contradictions
as for which direction i would expect grain orientation to make things strongest in, i really have no idea at all
______
† last night, for example, i read https://www.mdpi.com/2075-4701/8/2/91/pdf and https://www.jstage.jst.go.jp/article/jjspm/63/7/63_15-00089/..., but also parts of https://pure.tue.nl/ws/portalfiles/portal/1584410/617544.pdf, http://www.diva-portal.se/smash/get/diva2:1352113/FULLTEXT01..., https://yadda.icm.edu.pl/baztech/element/bwmeta1.element.baz..., https://www.imerys.com/public/2022-03/Specialty-Carbons-for-..., and https://backend.orbit.dtu.dk/ws/portalfiles/portal/200743982..., but i was maybe on a bit of an atypical metallurgy bender. none of these are more than marginally relevant to the questions at hand of forging, strain-hardening/work-hardening, and grain structure orientation
I'm not saying cold working doesn't happen, or doesn't affect strength. It certainly does. I'm pushing back on the idea that forging creates superior strength via grain flow. One of the sibling comments pointed out the MIL spec materials handbook[1] where he found some materials that do exhibit a strength dependency on grain direction. That is interesting.
That seems to be the exception rather than the rule. If you go to page 3-220 in that spec, they show 5052 Aluminum in varying degrees of cold work (H32, H34, H36, and H38), where higher degrees of cold work have higher ultimate and yield strengths, but the L vs LT directions are identical in many cases, or 1 different. That goes against the general idea that forging grain flow creates superior strength in general.
[1]http://everyspec.com/MIL-HDBK/MIL-HDBK-0001-0099/MIL_HDBK_5J...
If you cold forge there are some benefits (but the question would be what can actually be reliably be cold forged and be a useful object in our precise world ?). If you hot forge and/or heat treat, most of the benefits are lost pretty fast, so it doesn’t make much difference.
As the OP seems to intuit there is probably not much real strength benefits to forging for useful objects in real use cases scenarios, the reason they are forged have to do with manufacturing processes more than anything else.
At least this is what I understand…
The first relevant example I found was on page 3-86, extruded 2024, 2.250 - 2.499 inch cross-section. For ultimate tensile strength, F_tu, the L (in the direction of extrusion) allowable is 57 ksi, while the LT (perpendicular to the direction of extrusion) allowable is 39 ksi. That's a 30% drop in strength.
[1] http://everyspec.com/MIL-HDBK/MIL-HDBK-0001-0099/MIL_HDBK_5J...
So it looks like the effect is very alloy dependent. I didn't see any of the steels having any notable directionality. Also Aluminum 6061 doesn't show any directionality either. Outside aerospace, I suspect that covers the majority of metal tonnage used.
A very good example of the affect of annealing tungsten wire is here [1] – note that (a) there is a very clear orientation dependence that some difficult geometric transformations will undoubtedly show means that they are aligned in the wire drawing dimension; and (b) after annealing at 1600 ºC for an hour the preference is slightly reduced but still about 15 sigma away from random...
[1] https://www.researchgate.net/figure/001-110-and-111-pole-fig...
This paper [1] has some good data in it:
"The experiments in this study were developed to verify the influence of the grain-flow orientation on fatigue life and its impact on the anisotropic properties of a mechanical component. To this end, steel specimens were made, and their fiber was oriented by machining and hot forging. Subsequently, they were subjected to flexo-rotational fatigue tests in a piece of specific equipment to determine their fatigue life."
(...) They then describe three parts: A, properly forged, B, improperly forged, and C, machined. (...)
"The results showed that specimens of configuration A achieved a much longer fatigue life than configurations B and C, actually doubling it. The results indicated a similar fatigue life behavior between configurations B and C. It is important to emphasize that this similar behavior between these two configurations is valid for this case analyzed (...)"
My opinion was formed from another area that is related : the pretense that “forged” knife are stronger, and hold their edges better, etc. I have seen some mostly nonsensical electronically microscope observations that didn’t prove anything except minor differences in “fiber” patterns that cannot be reliably be shown to be better in experimental protocols (provided you heat treat the metal in the same way and everything else being equal in particular the particular alloy).
I think this is one of those things that people keep repeating without any evidence because very is a large amount of marketing behind it as well as vested interests to sell more expensive supposedly superior “artisanal” stuff.
There are many examples of the likes, being mostly belief/lores repeated ad nauseam that becomes “true” just because everyone is saying it, yet with no hard evidence !
The only people I know who have worked with this have used it to make superconducting magnets, explosively forming either titanium or high grades of nonmagnetic stainless (A4, which has µr ≈ 1) without causing marsenite formation due to machining. This includes a major international MRI scanner manufacturer, for one relatively niche product. It's like the "extreme" version of metal spinning [3] – forcing a rotating chunk of metal against a rotationally symmetric mandrel.
[1] https://en.wikipedia.org/wiki/Explosive_forming [2] https://www.researchgate.net/figure/Variation-of-peak-over-p... [3] https://en.wikipedia.org/wiki/Metal_spinning
Example: In a shell and tube heat exchanger, the tubes might have some really reactive stuff in it so you might make the tube side out of indium , titanium, nickel, or even an expensive stainless steel like S32205/S31803. The shell side might just have river water for cooling, and can just be painted and have a sacrificial anode somewhere inside.
The bulkhead where all the tubes penetrate (the "tubesheet") might be 6' (180cm) in diameter and 4-8 inches (10-20cm) thick - an extraordinarily expensive hunk of material (or possibly not even available in the thickness needed) when made 100% of the more exotic materials; easily in the 6 figure range.
Sometimes this problem is solved by having a welder coat the entire surface with weld metal that's good enough to withstand the corrosion characteristics of the process stream, but with larger parts this can take _days_; with some metallurgies (e.g. brass) it's not even possible.
Instead, the practice was to explosion bond a "thin" layer (1/4" (6mm) or so) of the expensive stuff to a more standard carbon steel forging. The tubes are usually very thin walled and welded/brazed to the cladding.
What's cool is the interface layer between the two metals looks like when two liquids meet with swirls and whorls of the two materials interleaving, but frozen solid.
They are actually now directly govt owned as of 2020, with future investment for a new heavy forge.
(The "local supply chain is vulnerable to political uncertainty over long term project funding" problem is much worse in regard to trains, and has resulted in losing most of our train building capacity. See HS2 fiasco.)
>The savings on a heavy bomber was estimated to be even greater, around 5-10% of its total cost; savings on the B-52 alone were estimated to be greater than the entire cost of the Heavy Press Program.
These are wild stats.
Great article! I was fascinated to learn about the Heavy Press program for the first time, here on HN[1] a month ago, and am glad more about it is being posted.
It makes me think: what other processes could redefine an industry or way of thinking/designing if taken a step further? We had forging and extrusion presses … but huge, high pressure ones changed the game entirely.
Pressure-injection molded hemp plastic certainly meets spec for automotive and aerospace applications.
"Plant-based epoxy enables recyclable carbon fiber" (2022) [that's stronger than steel and lighter than fiberglass] https://news.ycombinator.com/item?id=30138954 ... https://news.ycombinator.com/item?id=37560244
Silica aerogels are dermally abrasive. Applications for non-silica aerogels - for example hemp aerogels - include thermal insulation, packaging, maybe upholstery fill.
There's a new method to remove oxygen from Titanium: "Cheap yet ultrapure titanium metal might enable widespread use in industry" (2024) https://news.ycombinator.com/item?id=40768549
"Electric recycling of Portland cement at scale" (2024) https://www.nature.com/articles/s41586-024-07338-8 ... "Combined cement and steel recycling could cut CO2 emissions" https://news.ycombinator.com/item?id=40452946
"Researchers create green steel from toxic [aluminum production waste] red mud in 10 minutes" (2024) https://newatlas.com/materials/toxic-baulxite-residue-alumin...
There are many new imaging methods for quality inspection of steel and other metals and alloys, and biocomposites.
"Seeding steel frames brings destroyed coral reefs back to life" (2024) https://news.ycombinator.com/item?id=39735205
> The largest, the 50,000-ton forging presses, were behemoths: each was the size of a ten-story building, and could exert enough force to lift an entire battleship. The 35,000-ton forging presses weren’t much smaller.
and then
> Following Germany’s surrender, the U.S. and the Soviet Union divided up its large press capabilities as well as its rocket scientists. The U.S. dismantled four German presses and had them shipped back to the states
I wonder what the logistics for moving something like that across the ocean was. I know Soviets dismantled a bunch of factories during the war and moved them far behind the front lines...wonder what that was like.
Based on my software experience, I can sort of go in blind and figure out how a system functions. I suppose that translates to real world too..
It drives my family nuts that I will assemble a piece of furniture without reading the instructions. But the thing is with a little mechanical sympathy, and a well designed product, there’s only one sensible way for the parts to go together, and if you organize them right while you disassemble it (granted, harder to do when shipping overseas) then you’re good.
Imagine you had a device where four hardened steel bolts held the critical parts together. It would be stupid if the handles used the same bolt sizes in mild steel, right? Someone will fuck that up and use the wrong spare parts or do deep maintenance wrong. You’d use a different size bolt so they can’t get mixed up.
Machines are extremely complex, and that's before you even touch electronics and hydraulics, both of which are highly complex systems. Simply moving large machine parts safely requires documented procedures, let alone order of assembly.
granted, he'll probably fuck up his first two or three pretty good without haynes or chilton
My dad will tell you I helped him rebuild a bike coaster brake at 14. But the truth is the only decision he made was to buy the repair kit. I got rags and laid all the parts out like an exploded diagram, we cleaned them or swapped them and they went back in the way they came out.
I worked as a bike mechanic for two summers in college. Cars have manuals and maybe the mechanic you work for has them. Bicycles do not. You’re all shade-tree until you’ve seen everything a couple times.
Given the assumptions, inaccuracies, and mistakes I've seen in some Haynes and Chilton manuals they'll probably fuck up with them. Factory manuals are usually worth the price (Honda's are, KTM's not so much).
Under no circumstances would I claim that rebuilding a motor was essentially figuring out how to build one from scratch. In software, maybe that's like claiming that figuring out how to configure a new Linux box is essentially the same thing as figuring out how to write an OS.
(i mean, if all the parts of your engine are trashed, you are going to have to machine replacements for them, and that might actually take you longer. but it's clearly achievable given that people have built internal combustion engines without a working example to take measurements from)
It's a bit academic, but set theory doesn't really apply to such fuzzy human things as knowledge and experience. Repairing and designing are different pursuits which might have a lot of similarities, but I wouldn't presume that a design engineer could competently do the work of a technician.
Just consider that any particular field of engineering as might be described by a lay person, can be far too broad and deep for an individual to be competent in all facets of it. I'm reminded of my neighbour asking for some help configuring email for her new iPhone, because she knows I do computer work. Mainly firmware.
repair and design have in common that they require a lot of hard thought about the causal relationships involved in making the artifact work, tracing the causal chains through until they break, then patching them up. but they both also certainly involve other skills that the other does not; design also requires figuring out how to make new things happen, which involves imagining things that have never happened, while repair also requires knowing how not to bust your knuckles or spill the gasoline
I'm much less convinced than you are about the availability of accurate and detailed manuals. Which is why I keep steering the conversation to more murky engineering projects.
But I do want to circle back to say that I did at some point higher up gloss over the importance of things like torque and clearances. I'm not trying to say that those are things you can just intuit. Even if we could both probably dig up an old mechanic who tightens things by feel.
It was at the end of a massively destructive war of annihilation.
FWIW here are Nissan factory manuals in all their glory: https://www.nicoclub.com/nissan-service-manuals
But I guess IKEA furniture is a pretty low bar to clear so there is that..
Or you're going to have quite an adventure when you go to do your thing and a random selection of bolt heads come pinging off at you at mach 5.
The free market probably could and would have optimized the situation at hand. Machining would have become cheaper, solutions to the fastener issues mentioned would be found and so on. This might even end up being better than the heavy presses - that's a technical question not an economic one - although the article makes it sound like the forging solution really is inherently superior.
Most discussions about trying to build industrial capacity in the US seem to focus on either our high labor costs or on the disinterest in capital to invest in low margin places. I would love to understand what time frame of guaranteed business the government provided these companies to convince them to participate, and also what other industrial processes the government invested in which failed to take off. Specifically, why didn’t this sort of thing work for the solar industry a few years back?
[1] https://www.lightmetalage.com/news/industry-news/forging/web...
on the other hand, the press release might be written by the same sort of people who say things like 'the world series', which is a baseball tournament between teams from the usa (and canada)
https://www.gasparini.com/en/the-worlds-largest-hydraulic-pr... says
> The United States leadership only lasted two years: in 1957 the Ukrainian company Novokramatorsky Mashinostroitelny Zavod (NKMZ), specialized in steelworks equipment, built two 75,000-ton presses. The first one, destined for a plant in Samara, is now owned by Alcoa’s Russian branch. The second was installed in Verkhniaïa Salda and is used by VSMPO-AVISMA, the world’s leading producer of titanium and other specialty alloys.
> Outside the two superpowers, France was the third country to equip itself with a hydraulic press of this size: also built by the Ukrainian NKMZ, this 65,000 ton presse hydraulique* was installed in Issoire between 1974 and 1976. Owned by Interforge, the machine is 36 metres high and manufactures components for Airbus, Boeing, the space and transport industries.*
...
> After 60 years, the USA has added a new 60,000-ton hydraulic forging press. Built by SMS Group and managed by Weber Metals in California, it started operations in October 2018.
> The heavyweight champion, of course, is Chinese: a machine with the incredible power [sic] of 80,000 tons is in operation since 2013 for the giant Erzhong Group in the province of Sichuan. As tall as a 10-storey building, its use is very confidential: it seems to be used to build parts for military aircraft, like its titanic sisters. To give an idea of the power of this machine, with its 780,000 kN it could easily lift an entire cruise ship. As often happens, larger does not mean better: it is not the most technologically advanced press in the world. It was built by adapting old USSR projects from the 1980s, and is currently underused due to competition from the other giants we mentioned.
either this derives from this longer post from 02022, or they both derive from a common source: https://www.linkedin.com/pulse/worlds-largest-hydraulic-pres...
the owner was at risk of bankruptcy in 02015: https://web.archive.org/web/20160809080032/http://www.france...
There is a Canadian company that is gearing up to make small reactor vessels like the BWRX-300 but so far I haven’t seen a sign they aren’t Nuscale 2.0
If for arguments sake it were a part for an AWACS or an aircraft carrier you might only need to make eight or a dozen. But even military aircraft tend to run into the hundreds.
We are part of a few companies just in time manufacturing so they pay for expedite processing on orders as small a one piece to a few dozen. And we can get production run orders in the tens of thousands.
I saw a link from some government minister in Canada named Don Morgan who stated a BWRX-300 would cost $5B (CAN), which comes to about $3.6B (US). $12/W (US) is not the worst, but it isn't great. Not clear if that was all-in cost or just overnight cost.
https://www.deassociation.ca/newsfeed/4-provinces-push-ahead...
https://en.wikipedia.org/wiki/Howmet_Aerospace
The big Cleveland press has its own wiki.
https://en.wikipedia.org/wiki/Alcoa_50,000_ton_forging_press
Most of the time they made turbine blades for jet engines, but if it was slow they would make golf club heads for PING and companies like that. In all the years he worked there, the golf club heads were the only tangible product of his work that I saw because everything else was tightly controlled in the facility.
Pratt & Whitney appears to have developed most of the technology.
https://www.americanscientist.org/article/each-blade-a-singl...
I wonder if they wore out?, something better came along?, or just no demand?
EDIT: or, according to hwillis' math, 2.5ft thick. I guess those could be useful for anchoring a zipline to the moon or something.
How would you weld even one foot of steel?
The idea behind forge welding is you get both parts nearly molten (e.g. "welding heat") then your hammer blow (or the pressure from a huge press) puts enough energy into the weld area to briefly melt it.
Also, hot rivets might be a better option than welding if you can get away with it.
It would take a LOT of passes.
Columbium is apparently an old name for niobium, and one perhaps still in use by American metallurgists.
There's no way anyone was making huge niobium forgings, though. Or nickel? Surely this is a reference to the use of those elements in superalloys.
As somebody who knows absolutely nothing about this stuff, I wonder—casting, I thought, was generally a lower quality option (like cast iron doesn’t have fantastic high-performance material qualities, and I had some crappy cast pewter toys as a kid). Are there different, higher quality casting processes, and I’ve only seen the bargain bin results? Is there a general ranking of the quality of the result or is it all very complicated and material specific?
The main drawbacks of casting are you get a hard, but brittle product with (generally) uneven quality. There are processes (like annealing, though I don't know how you anneal a massive component) that can solve these problems, but all iron/steel is "cast" at some point.
Cast iron is a material, not a process. It's an unfortunate legacy term for very high carbon steel (>2% by weight, or <11 iron atoms per carbon atom). For reference "standard" steel is ~.08-.18% carbon, and high-carbon steel is ~.8% carbon.
The >1% carbon precipitates out into graphite within the steel, causing it to behave totally differently. Less rusting, but weaker and much more brittle when solid. Less viscous when liquid, so you can cast long and thin parts.
> Are there different, higher quality casting processes, and I’ve only seen the bargain bin results?
There are, but it mostly is independent of the material. Some turbine blades are cast as single crystals for heat stability; you can't really cut a single crystal without introducing cracks and issues. There's also vacuum casting and spin casting (using a centrifuge to force liquid into the mold), which lets you cast metals that react with air or cool too quickly for normal methods.
Most of the variation in process is about the final form you cast into, though. Engine blocks are sometimes cast into a one-off ceramic shell that is sprayed onto a sand form. It's an expensive process but it lets you do the whole thing in one step.
> is it all very complicated and material specific?
It is very material specific. Fundamentally its all about shaping the grains. In many steels you can physically alter grains. In others, like precipitation grains (aluminum alloys, some steels) the structure is determined by the cooling and you can't physically shape them. In that case you may often get a better structure by casting since you can choose how to cool parts down, while a billet will have a homogenous structure that is usually worse towards the center.
If one adds some magnesium or cerium to the alloy, the graphite precipitates out as spherical nodules rather than feathery dendrites. The resulting material, called ductile iron, is much less brittle than traditional cast iron.
An advantage of the higher carbon content is a reduction in the melting point (by > 300 C), so the material is easier to cast than low carbon steel.
Wikipedia has a image of an connecting rod that has been etched to show the grain:
https://upload.wikimedia.org/wikipedia/commons/5/5c/ForgedCo...
You can see the grain has been stretched along the length of the narrow parts. Wrenches are another example of something that's commonly forged for this reason.
Casting has problems with thermal expansion, plenty of materials shrink significantly as they cool and complex parts cool unevenly which can cause them to break or deform.
Casting has problems with microstructure, plenty of materials, especially steels develop complex crystal structures with multiple phases of materials as they cool from liquids and even extensively in hot solid phases. It's hard to control this in a cast part.
Casting has problems with precision. The molds just can't be all that precise when in machining, a thousandth of an inch can be a relatively large distance.
However casting gets a bad reputation because most of the time you see it it's because it's actually very cheap, cheap materials, cheap process, minimal post processing. Higher cost things don't necessarily realize the savings from casting as much so they don't use it. And also a lot of higher quality materials have higher melting points which require more advanced tools to melt and handle.
Plenty of things though are cast and then machined, you notice this if you look.
Also, the processes are not really independent. It can be much cheaper to do a rough casting, and then machine just the critical faces of it, instead of using an “off the shelf” hunk of metal and machining it all into shape. So it’s not really “casting is superior to machining” or vice versa. More that machining is high precision but expensive. Casting has some up-front cost but once the patterns are made, each item will use material quite efficiently.
> The spokes are really hard to make precisely with machining
That is not true.
Cast iron is fantastic for building machine out of - while it isn't as strong, it is stable against vibration. There is a reason engine cylinder selves are often cast iron.
> I had some crappy cast pewter toys as a kid
Those were pot metal, not pewter (pester has many definitions but implies some qualty control). They are made out of whatever melts in a pot - often whatever is cheap at the recycle yard (without trying to identify what is in the metal - including lead which shouldn't be used in toys). Typically no control of the alloy was made and often they start with several different things that are great in isolation but when mixed result in bad behavior. Then the next time the make the toy they use different mix and get different properties. If you spend a little extra to get a known alloy pot metal is a high quality castings with great properties.
> I’ve only seen the bargain bin results
You have likely seen a lot of non bargain bin results. However since the parts are invisible you never thought about it or the alloy used. You see the failures and so casting gets a bad reputation because it is obviously used in the cheapest things with low quality control. (the door knobs in your house are likely cast pot metal plated with brass, but they last for decades)
I thought it was because cast iron had very high resistance to wear.
"America's Iron Giants" https://youtu.be/hpgK51w6uhk?si=5BjwmlSMAAKzVYzS
I imagine extremely large construction and digging. Kilometer-tall buildings and deep large tunnels.
Tangentially, if there were a war today would the US be able to produce as much as it did in WW2?
It might be easy to argue over the exact degree of similiarity, but I'd argue that the US has repeatedly made manufacturing investments since the 1950s. Buried in bills signed into law, you'll find such investments.
Recent examples include the Recovery Act of 2009 or the American CHIPS act of 2022.
https://en.wikipedia.org/wiki/American_Recovery_and_Reinvest...
However, this might not matter as much now as it did in the past due to nuclear weapons being the primary deterrent in war these days, and the fact that our standing fleet of aircraft, aircraft carriers, nuke subs, tanks, etc... is essentially second to none. Additionally what we do have is highly capable and extremely specialized, in my opinion, leading to not really needing as many (quality over quantity). Take for example, an F35, which doesn't really have an equal in the skies, we have over 630 of them, with the goal of having around 2500. China only has 300 J-20s which are basically a copy of the older F22. Russia only has 22 non-test Su-57s. Would we have a realistic need to build 1000 of them within a year?
Due to many factors, but primarily free trade and globalization, it's unlikely that we ever see that non-automated manufacturing capacity return, though if needed we could probably mobilize the economy via the defense act to force more manufacturing capacity, though it's hard to imagine we would currently need to.
No, but that is different from not investing. Today the US invests more in automation and engineering and less in manual labor.
> if there were a war today would the US be able to produce as much as it did in WW2?
It took several years to ramp up to WW2 level production. We would see the same, a couple years of trouble on the fronts while building industry at home, then when the industry is built up massive production.
Historians (amateur so I'm not sure if they are right) tell me Hitler was ready for WW2 first and Italy begged him to not start the war as their industry wasn't ready. However France and Briton saw the war coming and were building their industry and so waiting might have made things worse.
Furthermore, all presses mentioned in the article have been surpassed by a 60,000 ton press that opened in Los Angeles, in 2018.
People with agendas will happily feed others narratives about the US not investing in manufacturing anymore, but it isn't true.
US manufacturing output has been steadily increasing since always, with the occasional 1-3 year dip during recessions. However, manufacturing does represent a lower percentage of our GDP with each passing year, despite the absolute value increasing.
It's a matter of perception. Most people don't directly see (or buy) the stuff manufactured in the US these days. Normal people don't buy nuclear power plants, aircraft engines, commercial aircraft, etc., and certainly not military hardware which the US makes a lot of. They do buy clothes and various consumer electronics, and they see "Made in China" (or for some clothes, places like Bangladesh or Vietnam or Cambodia) printed on all those, when 50 years ago all that stuff had "Made in USA" printed on it, or for the nicer consumer electronics 30-40 years ago, "Made in Japan". People still might be getting a CPU for their laptop computer manufactured in the USA, but the chip will probably say "Made in Malaysia" because only the silicon was made in the US, and was then shipped somewhere else for packaging.
>However, manufacturing does represent a lower percentage of our GDP with each passing year, despite the absolute value increasing.
I'd say that's probably a bad sign: what other sectors are increasing? Likely they're things that aren't actually productive, such as healthcare (the value received does not represent the price paid in the US by a long shot, compared to other advanced economies; most of the money goes to insurance companies and waste), legal services, ever-increasing real estate valuations, etc.
At heart, this is the story of using less labor to product a unit of output, and possibly also improving the quality of those units of output. This led to much better outcomes for society. Was anybody then scared of what would happen to the riveters? Maybe, but those voices would have been drowned out.
These days, production is demonized, particularly at scale. Is there any successful producer being celebrated for being so? Are there any new, innovative, labor-reducing technologies being celebrated?
Does it take a war to snap us out of our fear of being better?
Yeah, must be the 50s.
My 75 years old carpenter is half deaf, his grandfather fell from a roof and died.
He himself fell off a roof in 1981 but was lucky and survived.
Just some thoughts seeing those men working in those conditions.
So I didn't think what I said was out of line. Obviously, I was mistaken.