Materials Engineering: A Narrative Pedagogy
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WM_Su2014_35

Welding Quality Summer 2014 Session · 1 section 1 cases · Watch on YouTube ↗ all files
Layer 3 — readable edition

§1. The Davenport Works air knife that never got installed [00:01]

§1.p1

They wanted the plate to hot-roll through the mill with a little upward curvature. It's a reversing mill, so the plate goes this way and that way. Sometimes you get Rocky Mountains on both sides, sometimes only one side. They actually ran one roll a little faster than the other, because you don't want the plate to cobble down into the bed of the mill — you want a slightly upward curvature. So one roll goes slower than the other, intentionally. That would create a little cup on the end where water would pool, and the water would cool it off while the operator was out there making his measurement, and then it goes through again. So one end was cooler than the other.

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§1.p2

I told her, you need to go do some calculations, and I showed her where to get the film boiling heat transfer data. She could explain 80% of the variation they were measuring based on the more rapid cooling for the longer time the water was present. She writes up her thesis. All they needed — and they have compressed air in a plant like this — I said, all you need is an air knife. You put a valve there, you run some piping across at the end, and you blow the water off the plate. Don't let it just sit there and evaporate off, okay. I figured the piping could cost ten thousand dollars to engineer, but you already own the compressed air, so what's the big deal.

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§1.p3

At the time I figured this has a one-day payback. You don't scrap one plate, you make ten thousand dollars. I was starting out then with these National Research Council committees with a guy, Owen Richmond, who was head of all the metal forming at Alcoa Research. So I told Owen the story. I said, Owen, it's in Julie's thesis. She's given the thesis to the Davenport Works but they're not going to read it, and they're certainly not going to pay attention. Oh Tom, no, this is something I will take care of personally. I said, okay fine. But I'll bet you ten thousand dollars — this is a Romney bet — I'll bet you ten thousand dollars that they don't. No, I'll take care of it.

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§1.p4

So about a year later we're at another one of these meetings, and we're having the cocktail hour, and I say, hey Owen, how'd that thing go at the Davenport Works? Do you owe me ten thousand dollars or not? He just turned on his heels and walked away without saying a word. So do you think they ever got the air knives at Davenport, fix their problem? No. This is the way it's done in American industry. Okay.

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§1.p5

So, okay, thanks. I filled it up with stories the last — stories.

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Cases referenced

  • Alcoa Davenport aluminum rolling mill thickness variation §1.p1

    Tom's graduate student Julie investigates thickness variation on hot-rolled aluminum plate at Alcoa's Davenport, Iowa works. Diagnosis: the deliberately mismatched roll speeds (to give the plate slight upward curvature and keep it from cobbling into the mill bed) create a water-pooling cup at the slower end. Film-boiling heat transfer at the cooled end explains 80% of measured thickness variation. Proposed fix: a compressed-air "air knife" to blow standing water off the plate after each pass. Cost: ~$10,000 in piping; the compressed air infrastructure is already in place. Payback: one scrapped plate. Owen Richmond (head of metal forming, Alcoa Research) personally promises to see it implemented. A year later: not done. Tom uses this as his closing parable for "the way it's done in American industry."

Layer 2 — cleanup edit
p1 00:01

Because they don't want, they want the plate to hot roll through the mill with a little upward curvature, and it's a reversing mill so they go this way and that way. And if you pulled, sometimes you get Rocky Mountains on both sides, sometimes only one side. And they actually ran this one a little faster than that one because you didn't want the plate to cobble down into the rolls on the mill, the bed of the mill. You want them to kind of have a little slightly upward curvature, so this one goes slower than this one, intentionally. That would create a little cup on the end where the water would pool, and then the water would cool it off while the guy's out there making his measurement or whatever, and then they go through it again, and so this was cooler than this.

p2 00:42

And I said, well, you need to go and do some calculations, and I showed her where to get the film boiling heat transfer and stuff. Do some — she could explain 80 percent of the variation they were measuring based on the more rapid cooling for the longer time that the water was present. She writes up her thesis. All we needed — they have compressed air in a plant like this — I said, all you need is an air knife. You just have a valve there, and you put some piping across here at the end, and you blow the water off the plate, and don't let it just sit there and evaporate off, okay. And I figured the piping could cost you ten thousand dollars, you know, to engineer the piping, but you already own the compressed air, so what's the big deal.

p3 01:24

So at the time, um, I figured this has a one day payback, right. You don't scrap one plate, you make ten thousand dollars, right. Um, so at the time I was starting out with these National Research Council committees with a guy, Owen Richmond, who was head of all the metal forming at Alcoa Research. And so I told Owen this, the story. I said, Owen, you know, it's in Julie's thesis. She's given the thesis to the Davenport Works but they're not going to read it, and they're certainly not going to pay attention. Oh Tom, oh no, this is something I will take care of it personally. I said, okay fine. I said, but I'll bet you ten thousand dollars — this is a Romney bet, right — I'll bet you ten thousand dollars that they don't. No, I'll take care of it.

p4 02:09

So about a year later we're at this another one of these meetings, and we're having the cocktail hour, and I'm CEO [sic], and I say, hey Owen, how'd that thing go at the Davenport Works? Do you owe me ten thousand dollars or not? He just turned on his heels and walked away without saying a word. So do you think they ever got the air knives at Davenport, fix their problem? No. This is the way it's done in American industry. Okay.

p5 02:38

So, okay, thanks. I filled it up with stories the last — stories.