The Great Bell of Dhammazedi was most likely a good deal bigger than the Tsar Bell, but unfortunately we have no way to confirm that … yet!
The largest diesel engine’s crankshaft is probably in the running for the largest forged piece, if not the winner. The crankshaft for the Wärtsilä-Sulzer RTA96-C’s crankshaft comes in at 300 tons. I don’t have any numbers for the crankcase, cylinder assemblies or heads, but since the engine weighs 2300 tonnes, I’d imagine each is similarly impressive for cast pieces. Time lapse of the assembly process.
I can well believe this.
I went into the Forgemasters building once, many years ago; there was a huge propellor hanging from the ceiling for some reason- it looked to be roughly the size of a double decker bus.
The crankshaft on engines that large are built up, that is they is consist of multiple forgings shrink-fitted together.
Also in general on the largest engines, and particularly Sulzer*, most of the structure like bedplate and cylinder frame are weldments, heavy steel plates welded together. Design rival B&W** has traditionally tended to go more for castings but the biggest of their engines also use weldments for major parts.
*now Winterthur Gas & Diesel Ltd, a subsidiary of China State Shipbuilding Corp.
**now MAN-B&W
Ok, so they’re out of the running for largest single forging. But now I’m even more impressed from an engineering perspective.
Shrink-fit!=weldment?
No. If you heat one side and cool the other side of the components again they will separate. Which is how you can repair things. Welding actually means the metal lattice is continuous across the join. There is no longer a join as such. It makes no more sense to cut the components at the weld as any other location, it will take just as much effort.
There are some interesting things happening in a shrink fit joint, but the metal lattice does not become a continuous thing.
I was just going to jump in on this one. With a shrink fit, you still have two discreet components. They can still be separated, just not easily. With a weld, there is a section where the metal of one component is mingled with the metal of the second, along with some filler metal in most forms of welding.
Soldering and brazing are kind of like using glue to hold different components together.
No. The crankshafts on those big engine are made by forging a series of pieces each consisting of section of the main shaft, the part in the center, and the ‘throw’ and crank pin the piston rod connects to. Then each piece has a shaft at one end and a hole at the other. The hole diameter is slightly smaller than the shaft diameter at ambient temp. You heat up the piece with the hole* till it expands enough to slip over the shaft with the two pieces at the correct angle. When it cools there’s enough tension to hold it in place even under the engine’s load. That’s a common method of joining, usually concentric cylindrical, big metal pieces. Large caliber artillery barrels were assembled similarly, out of several hoops.
The bedplate, the engine’s own foundation** in contrast is made out of thick steel plates welded together. A finished piece like that is called a weldment. A whole ship’s hull is kind of a weldment but the term isn’t typical used in that case. It’s more often used to distinguish something you could build another way. For example you could cast the bedplate, or make it out of several castings bolted together. As mentioned B&W’s design philosophy leans to castings on relatively smaller engines in this category of huge diesels, Sulzer (the design in original link) has favored welded construction.
*or cool down the piece with the shaft
** as opposed to the foundation in the ship’s hull the engine sits on, the great majority of such large engines are used to propel ships though sometimes also as relatively small shore electric power plants.
The heaviest forgings seem to be in the nuclear power plant industry. The link below lists the presses, and japan steel works is the champ, able to accept 650 tonne ingots
But another measure of a press is the force it can exert. JSW press above is only a 14000 tonne press. The heaviest hydraulic press is in china, a 80,000 ton press, a derivative of the 75000 ton Russian press. France has a 65000 ton press.
The US has the big 50. , Presses capable of exerting 50000 tons of force, for aviation, like the f22 bulkhead, sr71 or Boeing airliner parts for example
These are giant machines
Great cites.
OK, so I’m on a roll here: I need the largest hunk of steel or iron possible on earth. Nothing more or less.
I went to find the specific heat of Iron (0.108 kcal/kg℃) and build mountains just like CERN.
Honest, I did, but I was doing it kind of stupidly and figured I could ask for a pedagogic working out from others. And of course we’d get the straight dope to what’s possible.
Followed by practical considerations, of course.
Yes, but the pillar wasn’t made in Europe. Indian smiths were already making steel in the 4th century BCE so there’s no reason they couldn’t have been casting iron 800 years later.
There’s iron and there’s iron. Iron and Steel in Ancient China by Wagner (1996)–even its pages when flipped through here via a search “ancient cast iron”–gives a nice overview of the issues. (He cites "early 5th century BC, FTR.)
The largest possible hunk is big.
From Earth - Wikipedia we see the Earth is about 6E24 kilograms of which 32% is iron. Iron being the most abundant element of the entire Earth. So we have 2E24 kilograms of iron to work with.
From Internal structure of Earth - Wikipedia we see the inner & outer core are, to a first approximation, pure iron. And form a sphere with a radius of ~3400km.
Extracting this iron sphere from its current location and erecting it upon a suitable pedestal for display is left as an exercise for the reader. Don’t forget to consider the gravitational consequences of this thing; they’re too large to ignore.
Late add:
The core ball is not the entirety of the Earth’s iron but it’s fairly close. Some rough calcs (Thanks Wolfram Alpha and ignoring many practical details) says 2E24kg of iron at room temp & pressure would form a sphere of radius 4E6 meters or 4E3 km. So call it 4,000km radius. IOW, about 15% bigger radius or diameter than Mars which clocks in at a mere 3400km radius.
xkcd has, of course, already weighed in (heh) on this topic: xkcd: Core
Thanks, but I said on Earth, not in it or of it. Assuming supply was limitless.
Won’t it melt itself eventually, so to speak, just like the mountains?
Jeez.
Making steel was done by smiths everywhere almost from the first. It can be made from wrought iron, but is very labor intensive. Also requires more charcoal. So it was only done for things that required high quality metal, i.e. knives and swords.
Getting the furnace hot enough to melt iron is the problem with making cast iron. They couldn’t do it reliably in the west until, as I said, some time in the middle ages.
W.K. Vale, in his article “Ferrous Metals” in An Encyclopaedia of the History of Technology, Ian McNeil, ed (Routledge:1993) brings us way back:
One of man’s earliest technical achievements was to make fire, and it could be that […] somebody noticed […] if two […] stones were banged together, they gave off a dull sound and did not crack or splinter: the charcoal (which is a very good and pure form of carbon) of the wood fire, urged perhaps by a strong wind, had reduced to iron some of the stones, which were actually iron ore. It would not be long before somebody had the curiosity to try other likely-looking stones round the fire, then it would only be a matter of time before somebody tried hammering one of the changed stones while it was red hot. He would find that he could beat it out into useful shapes which, when cold, were strong and did not break or bend easily. […] At all events, ironmaking had spread to Europe by about 1000 BC from the Middle East, where it apparently began much earlier.
At first, and for many centuries, […] [A] group of men working for several hours could only make a piece of iron perhaps not much bigger than a man’s fist, and weighing no more than one or two kilograms…
And that’s it–wrought iron rules the roost until 1400s, with the invention of the blast furnace, “introduced near Liège in what is now Belgium some time towards the end of the fifteenth century, [and] reached Britain by about 1500 and spread slowly throughout Europe.” [ibid.]
In between caveman and Renaissance man the most important smelting process used --and how dare I of all posters not note this–was able to produce bloom:
A bloomery is a type of furnace once widely used for smelting iron from its oxides. The bloomery was the earliest form of smelter capable of smelting iron. A bloomery’s product is a porous mass of iron and slag called a bloom. This mix of slag and iron in the bloom is termed sponge iron, which is usually consolidated and further forged into wrought iron.
This is much more likely how copper smelting was discovered, rather than iron. Copper had been smelted about 4000 years or so before iron. Iron was more likely to have been discovered by copper smiths when they got some iron ore mixed in with the copper ore.
Except as noted above, nothing you posted contradicts anything I said. Possibly you think it does because it doesn’t say that early smiths could make steel. OK, here’s how that happens.
When they got a bloom of iron, i.e. a mixture of pure iron and slag, they took it to a forge for further work. Further work meaning pounding it with a hammer in a warm carbon-rich environment. This shaped the iron into whatever final product they wanted and also physically removed the slag. Now if they only did it for a relatively short time, they would get a wrought iron object and it would still have some slag left in it. Except for the slag, the wrought iron would still be pretty much pure iron.
But if they kept working the piece for significantly longer, two things would happen. First, they’d remove virtually all the slag. Second, some of the carbon in that environment would migrate (or dissolve) into the surface of the iron. That would convert the iron (or at least the surface iron) into steel. Steel, as you may know, has about .8 to 1% carbon. So if they did this too long, they’d get too much carbon and ruin the piece.
They didn’t know about carbon and such, but they worked out by trial and error how to make a good steel knife or sword. It no doubt took a while to do that, so the thing about “from the first” is not quite accurate. But in terms of the total time iron has been produced, it was fairly short.
At any rate, it took a lot of extra work to convert wrought iron to steel, so they only did it for the most critical items: knives and swords. Other iron objects, like hammers, anvils, and plowshares, could be made with wrought.