How to build a 50k ton forging press • Hacker News Board

Re: How to build a 50k ton forging press

#191

Post by seec » Thu, Aug 29, 2024, 8:44 PM UTC

abe_m wrote: post #110

hwillis wrote: post #20

> Forgings have the added advantage of variable grain direction which generally can be tailored to the stress patterns of a specific design. 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 o…

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…

I very much agree with you and also would really like some clear evidence of that.

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 !

Re: How to build a 50k ton forging press

#192

Post by seec » Thu, Aug 29, 2024, 8:48 PM UTC

abe_m wrote: post #178

buildsjets wrote: post #162

Earlier quoted context omitted.

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 I will note that MIL-HDBK-5 is no longer valid for actual aerospace design, as it has been superseded by Battelle Institute's MMPDS Handbook, which is locked behind a very very tall paywall.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 ar…

That’s the problem of capitalism : you need it but too much of it becomes a disease for the society abusing it… Much of the western world is starting to feel the effects…

Re: How to build a 50k ton forging press

#193

Post by seec » Thu, Aug 29, 2024, 8:57 PM UTC

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…

So basically what you say is agreeing with his observations ?!

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…

Re: How to build a 50k ton forging press

#194

Post by seec » Thu, Aug 29, 2024, 9:04 PM UTC

elzbardico wrote: post #169

pjc50 wrote: post #143

Earlier quoted context omitted.

We're not going to build the nuclear reactors either. The problem will finally be solved by re-permitting onshore wind and a lot of batteries imported from China. (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.)

This is basically a pipe dream. But as long as the subsides are going to Big Green scammers, we will have numerically ignorant journalists peddling this bullshit.

I don’t understand how anyone can push that “solution” with a straight face. Surely they have worked out the numbers and figured out it’s not realistic at all, right,…,right ?

Re: How to build a 50k ton forging press

#195

Post by seec » Thu, Aug 29, 2024, 9:09 PM UTC

WheatMillington wrote: post #78

hinkley wrote: post #49

Earlier quoted context omitted.

There’s a UX school that says that if the user needs the manual you fucked up. I mostly subscribe to that school. Mostly. 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…

Your viewpoint is rather naive in the mechanical world. OK it's enough to assemble a coffee table, now try an engine with 2,000 parts. Without a manual how can you set bearing clearances? How do you know how much thrust clearance there should be? How do you know which way up a piston ring goes, or how much torque to apply to a head bolt? Machines are extremely complex, and that's before you even touch electronics and…

Yeah I laughed my ass off reading that. Something as basic as assembling a modern carbon bike can have you make a hundreds dollars mistake but there will always be smartass like those who always know better than the people who actually engineered the stuff.

But I guess IKEA furniture is a pretty low bar to clear so there is that..

Re: How to build a 50k ton forging press

#196

Post by ethbr1 » Mon, Sep 02, 2024, 4:54 AM UTC

thaumasiotes wrote: post #29

hwillis wrote: post #20

> Forgings have the added advantage of variable grain direction which generally can be tailored to the stress patterns of a specific design. 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 o…

> 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.

One of the most interesting things I learned about blacksmithing (aside from all the metallurgy because I'm not a ME), was how much more valuable "the right hit" was than "the heavy hit."

Sure, it takes a ton of muscle, but you can quickly screw up a piece by repeatedly beating the hell out of it.