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How to build a 50k ton forging press

construction-physics.com

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Re: How to build a 50k ton forging press

#171

Post by zro »

kragen wrote: post #158
jessebro wrote: post #152

Earlier quoted context omitted.

HDPE is also what Nalgenes and the like are made of (or used to be anyway), and is very popular for storing chemicals as well. It is very nearly completely inert.

you cunninghammed me: nalgenes are polycarbonate, which is a lot less inert all the polyethylenes are relatively inert, because polyethylenes are in some sense just heavy paraffins. paraffin is germanized latin for 'relatively inert'

The clear Nalgenes are polycarbonate, but the opaque ones (sold as "Ultralite Bottle" on their website) are made of HDPE

Re: How to build a 50k ton forging press

#172

Post by advisedwang »

refurb wrote: post #147
advisedwang wrote: post #77

This should be a lesson for free-market advocates, especially those who see the US economic boom as a result of laissez-faire economics. In reality there are opportunities the free market doesn't take, and wise government intervention can yield enormous benefit to the public.

Do you feel that the free market wouldn't have adopted it at some future point in time?

I don't believe the free market would ever have produced the heavy presses. The coordination problem between making designs that use the heavy press and the investment to make the presses is essentially the prisoner's dilemma - each actor reaps a large reward if they both commit but loses massively if only they commit. The outcome is that they don't commit, especially if you add in real-world factors like alternate uses of the investment that competition tends to force the businesses involved into. The only hope would be something vertically integrated that can commit both, but there's no particular reason to believe that such an enterprise could enter into the market.

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.

Re: How to build a 50k ton forging press

#173

Post by baud147258 »

azalemeth wrote: post #100

If you're reading this article, you may wish to know that arguably a "counterpart" to heavy press forging is explosive forming [1] in which a chemical high explosive is used to force a template material against a template. The overpressure generated by the explosive can be equivalent or maybe even greater than heavy press forgings (a 50,000 US short ton force press exerts ≈500 MN force; peak overpressure close to det…

I heard it from my brother who visited one such company, where they use explosive forming to shape metal parts used oil refinery; if I remember correctly for the corrugation on the metal that separate the hot and cold liquid in an heat exchanger, with the idea behind using explosive forging was that it allowed them to shape a big sheet in one go.

Re: How to build a 50k ton forging press

#175

Post by kragen »

PuffinBlue wrote: post #167
kragen wrote: post #158

Earlier quoted context omitted.

you cunninghammed me: nalgenes are polycarbonate, which is a lot less inert all the polyethylenes are relatively inert, because polyethylenes are in some sense just heavy paraffins. paraffin is germanized latin for 'relatively inert'

And you have Cunninghammed me :-) 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-c…

oh, thanks! i only knew the pc ones

Re: How to build a 50k ton forging press

#176

Post by abe_m »

azalemeth wrote: post #148
abe_m wrote: post #110

Earlier quoted context omitted.

I'd really like to see some backing of these claims. I've seen "grain flow" claiming big gains for years in various enthusiast magazines (bike, motorcycles, cars, etc) as to why components are forged. 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 str…

The best evidence for grain flow on a really atomic scale comes from what is called texture analysis in X-ray or electron-beam crystallography (or related techniques): you get a deviation in the distribution of Bragg peaks due to the fact that you have a non uniform distribution over the orientation of the unit cells within the crystallites in the bulk material. You can fit this in a spherical harmonic basis and quit…

I'm not saying grain flow doesn't exist. My claim is that I can't find any support for the idea that grain flow results in superior strength characteristics in the grain direction.

Re: How to build a 50k ton forging press

#177

Post by abe_m »

bobeboph wrote: post #136
abe_m wrote: post #110

Earlier quoted context omitted.

I'd really like to see some backing of these claims. I've seen "grain flow" claiming big gains for years in various enthusiast magazines (bike, motorcycles, cars, etc) as to why components are forged. 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 str…

MIL-HDBK-5 [1] is a good publically-available source for strength allowables for several aerospace alloys, including multiple directions relative to the grain for some of them. 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…

Thanks for slogging through that one to find an example. I've come across that handbook before, and went looking through it in the alloys I normally work with. In the alloys I normally see, the L and LT are either identical, or with a couple digits in the least significant digit.

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.

Re: How to build a 50k ton forging press

#178

Post by abe_m »

buildsjets wrote: post #162
bobeboph wrote: post #136

Earlier quoted context omitted.

MIL-HDBK-5 [1] is a good publically-available source for strength allowables for several aerospace alloys, including multiple directions relative to the grain for some of them. 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…

Thanks for posting that as I was about to! I will note that MIL-HDBK-5 is no longer valid for actual aerospace design, as it has been superseded by Battelle Institute's MMPDS Handbook, which is locked behind a very very tall paywall. The MIL-HDBK is still all perfectly good data. https://www.mmpds.org/

I think it is unfortunate the US government got rid of all their MIL and STD standards. You used to have a rich resource of technical specifications for materials, fasteners, fittings, etc for free access. Now they are pretty well all cancelled and have been moved to organizations like SAE and ASTM where they are hundreds of dollars per copy. For the metallurgical data, I'm curious if these successor organizations are actually generating any new data. Whenever I'm looking up references like that hand book, it appears they all summaries of investigations that happened back in the 1960's and earlier.

Re: How to build a 50k ton forging press

#179

Post by abe_m »

kragen wrote: post #127
abe_m wrote: post #110

Earlier quoted context omitted.

I'd really like to see some backing of these claims. I've seen "grain flow" claiming big gains for years in various enthusiast magazines (bike, motorcycles, cars, etc) as to why components are forged. 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 str…

your comment is an extremely valuable contribution! 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…

I'm not sure what you thought was contradictory within that quote. I thought it was reinforcing a single idea? I was pushing back on the idea that very high reduction ratios keep causing higher and higher strength. There is a pretty low limit to the amount of deformation you can make in steel and aluminum before you wreck the metal. You need to keep resetting the cold work via annealing to be able to keep forming the metal. Cold work is just done as the final pass with a very limited final dimensional reduction in rolling.

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...

Re: How to build a 50k ton forging press

#180

Post by rendall »

I first learned about these presses several years ago from the YouTube channel Machine Thinking which is excellent and unfortunately infrequent. The linked video has some excellent footage of these beasts in action.

"America's Iron Giants" https://youtu.be/hpgK51w6uhk?si=5BjwmlSMAAKzVYzS

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