Aluminum and strength

http://leancrew.com/all-this/2015/08/aluminum-and-strength/

by jessaustin • 11 years ago

56 29 11 years ago

leancrew.com

jessaustin• 11 years ago

...we can tell how cool Lew is from his backwards baseball cap.

Note to self: stop wearing caps that way before beard starts turning white.

charlesbarbier• 11 years ago

This article is quite interesting but I'm not too sure why the author felt the need for such a pedantic attitude toward the guy from the video. Its presumptuous without adding much to the discussion.

insaneirish• 11 years ago

Because Dr. Drang (his pseudonym) has a PhD in civil engineering, and is a practicing Professional Engineer specializing in failure analysis, making him uniquely qualified to comment on such a video's technical shortcomings.

If you follow him, he often includes a delightful amount of sarcasm and snark, enjoyably so.

nostromo• 11 years ago

Backwards hats go back to at least the mid-80s. By that regard, they should now be a sign of middle-aged wisdom, not of youth.

sic1• 11 years ago

this guy gets it, well said, sir. "darn kids and their forward hats"

Gibbon1• 11 years ago

Advice to whipper snappers, stop wearing 'vendorwear' after 30.

peterwwillis3• 11 years ago

I'd even go one further and suggest people start dressing like adults at 30, but the geek crowd would revolt if they didn't get to wear t-shirts with gamer slogans and Vibram FiveFingers.

chrisbennet• 11 years ago

Maybe it's an age thing, but these kids with their hats on backwards or even worse, sideways, look retarded to me. Live and let live though.

Admittedly, I've turned my baseball cap around backwards once in a while but it wasn't to look cool. (The brim of a baseball cap interferes with a rifle scope for example.)

iaw2• 11 years ago

This is pretty interesting because it raises the question about additional applications of this and similar alloys in the future. I wonder what, if any, material property drawbacks there are for the new alloy.

bajsejohannes• 11 years ago

He mentions one in the video, namely corrosion.

I'm sure there are other drawbacks as well. In fact the strength--which is seen as a benefit here--could be a drawback in a different application.

bigger_cheese2• 11 years ago

Usually in industrial design when you select a material you do so based off a constraint selection process: https://en.wikipedia.org/wiki/Material_selection

Typically you have material specific constraints (workability, cost, ease of sourcing) and application constraints (for a phone case this would be weight, stiffness, min/max dimensions things like that).

Once you have determined the constraints you can solve for the objective function using numerical methods i.e. Solve all the simultaneous equations.

That will identify the materials which are most suited to the chosen application. And will eliminate materials with drawbacks that cause them to fail to meet the constraints (so you don't end up with a iphone case made from diamond which costs a fortune or from ceramics which weigh a tonne).

digikata• 11 years ago

Could it be an alloy designed by Liquidmetal?

https://en.wikipedia.org/wiki/Liquidmetal

amatus3• 11 years ago

Looks like the Liquidmetal alloys are zirconium-based, the XRF showed that it was an aluminium-based alloy. So, no.

amatus3• 11 years ago

It's interesting that the new alloy was not recognized by XRF. In the video it looked like they had a large set of standards from which to build an empirical model. I don't know how likely it is that Apple created their own alloy, but I have experience with XRF analysis and I know it's easy to make mistakes preparing a sample. It's possible the tungsten came from the sandpaper used to remove the anodization layer or it might have been part of the anodization layer. Another tricky detail when analyzing materials is how the different elements adhere to the surface. The X-rays only see the atoms at the surface. If sanding the alloy removes more of a softer metal or smears it over the surface covering the other elements you may get inaccurate results.

iaw2• 11 years ago

Do you know if there's been experimentation with tungsten alloying of aluminum in the past? The thing that surprises me here is that if Apple did create an entirely new alloy with novel properties, why weren't those metallurgical characteristics already known? It's not like metallurgy is a new field.

amatus3• 11 years ago

Sorry, I only know some XRF, I don't know metallurgy.

rsfern• 11 years ago

It seems there's been a bit of research into Aluminum Tungsten systems[1]. The alloy systems described in the abstract are strengthened by particle formation (also called precipitation hardening), which is the primary strengthening mechanism used in most Al alloys[2].

In general, alloy design is an extremely high dimensional problem. You have composition, the forming processes, and heat treatments which all can profoundly affect the properties of the finished product. It's only since the fifties or so that we've really started to understand the internal structures of metals and how they affect properties like strength, and there are many open questions yet.

[1] http://link.springer.com/article/10.1007%2Fs11661-008-9593-3 [2] https://en.m.wikipedia.org/wiki/Precipitation_hardening

bigger_cheese2• 11 years ago

I'm a materials engineer I graduated in 2010 back when I was at uni very little of the curriculum was dedicated to non-ferrous metallurgy.

We probably spent as much time studying ferrous alloys as we did on Aluminium, Titanium, Copper and Nickel combined.

That said I suspect the reason is likely patent related. Metallurgy is not a new field but Aluminium alloying is relatively new wasn't really until after WW2. Alot of industrial research tends to be locked away behind patents.

racecar789• 11 years ago

Heat treatment is a dark art. What works for one heat treater may not work for the other. Also, heat treaters are somewhat reluctant to share their secret sauce with customers.

General hardening is no problem. The challenge is when a company needs a very specific hardness. There is a fair amount of trial and error with the heat treater (at least at first) before they get it right.

arcadi_tepes• 11 years ago

Its also interesting the on-device readout for the new alloy does not show a tungsten peak. https://www.youtube.com/watch?v=ChUsy8gWwvo&feature=youtu.be...

The printout shows it, but is ~.08% off from 100%, which I assume is the Mg peak. But its a pretty big swing to go from no Tungsten to .106% Tungsten. I'm inclined to believe its a misread due to sandpaper or the coating (tungsten carbide coating on aluminum is very much a thing).

I know metallography is expensive, but its weird to me to have such cool gizmo for XRF and to have a lab do such analysis and not do something simple like hardness testing. That is cheap and fast. Well, fast anyway. I can't comment on lab larbor costs.

Instead of a lab, hitting up your local university materials lab for a grad student to do a quick hardness test and tensile testing would give very nice information and a basic guess as to type of material. XRD would also be more accurate than XRF I think, with proper preparation. Also, you would never test the cases as-is. The structural variable is small but important. A flat sample is better.

brandon2722• 11 years ago

I couldn't find it in the quick digging I did; can anyone tell me where he got the 6S case, which he describes as a case that is "likely" from the new 6S? I assume it's either a technical reproduction based on rumour or an intentional gift from Apple to build hype?

kaolinite• 11 years ago

During the initial production of a new iPhone, which seems to start a month or two in advance of the release, parts are regularly smuggled out of the factories - especially case backs. They're sold to case manufacturers mainly who want the specs so they can design iPhone cases that are out on launch day.

brandon2722• 11 years ago

Interesting! Wouldn't that make him in possession of stolen material?

Animats• 11 years ago

I have to laugh at Apple's efforts to toughen up their phones. I own a Caterpillar brand phone, which will survive being run over by a truck.[1][2] Drops on cement result in zero damage. When an Apple product can pass IP67 certification, then they can talk about ruggedness.

[1] https://www.youtube.com/watch?v=mVPku-xItv8 [2] https://www.youtube.com/watch?v=sggbV7j_rLA

Aluminum and strength

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