Author Topic: Aluminium Lithium Manufacture  (Read 17937 times)

Offline zaarin

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Aluminium Lithium Manufacture
« on: 02/08/2012 06:57 PM »
I felt that this material deserved a thread of its own. I ask for a discussion about this lightweight material and its application in spaceflight hardware and possible a future for domestic use also.

I know Weldalite 049 can be welded and is quite easy to work with but at no net weight-loss compared to aluminum.

Alloy 8090 boasts the lowest mass/volume ratio but it cannot be welded. I know its makeup is 2.45% Li, 0.12% Zr, 1.3% Cu, 0.95% Mg, the rest is balanced with Aluminum.

Elon Musk recently demonstrated "friction stir welding", I'm still not quite sure how this process works.

I ask because I am doing research into portable solar tracking solar ovens and I am finding solid steel gears to be too heavy for portability and I think AL-LI gears may be the answer.

Please can you enlighten me as to how this is made? I think microwaving mobile phone batteries and bean cans is NOT the way to make it.

http://en.wikipedia.org/wiki/Al-Li


Offline Jim

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Re: Aluminium Lithium Manufacture
« Reply #1 on: 02/08/2012 07:22 PM »

I ask because I am doing research into portable solar tracking solar ovens and I am finding solid steel gears to be too heavy for portability and I think AL-LI gears may be the answer.



Gears not a task for AL-LI, there are durability issues for gears.  look at other aluminum alloys. Or even composites. 

 AL-LI is not for a lay person to make, users get it from ALCOA
« Last Edit: 02/08/2012 07:25 PM by Jim »

Offline zaarin

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Re: Aluminium Lithium Manufacture
« Reply #2 on: 02/08/2012 07:25 PM »

Gears not a task for AL-LI, there are durability issues.  look at other aluminum alloys.

I think AL-LI gears would be a lot more durable than wood or plastic.

Nevertheless, could you suggest another lightweight material more durable?

Offline FuseUpHereAlone

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Re: Aluminium Lithium Manufacture
« Reply #3 on: 02/08/2012 07:27 PM »

Elon Musk recently demonstrated "friction stir welding", I'm still not quite sure how this process works.

I'm not sure it counts as demonstrated since friction stir welding Al-Li has been in use since the late 90's on Delta II/IV:
http://www.boeing.com/news/frontiers/archive/2004/september/i_tt.html

and Space Shuttle:
http://www.nasa.gov/centers/marshall/pdf/104835main_friction.pdf

But I'm just splitting hairs...an interesting side note, Alcoa recently announced that it's ramping up it Al-Li output.

http://www.marketwatch.com/story/alcoa-expanding-aluminum-lithium-capabilities-to-meet-growing-aerospace-demand-for-its-industry-leading-alloys-2012-01-25

Quote
"In addition to producing a wide range of billet sizes up to 33-inches in diameter, we will also be able to produce slab capable of producing wing skin plate and fuselage sheet for any current or planned commercial air program," said Roegner. "Our process, thermal and filtration systems all will be state-of-the-art."


Offline Jim

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Re: Aluminium Lithium Manufacture
« Reply #4 on: 02/08/2012 07:27 PM »

I think AL-LI gears would be a lot more durable than wood or plastic.


Depends on the plastic.  Also, what is the duty cycle of the gears, how often are they in use, RPM, loads, etc.

Offline zaarin

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Re: Aluminium Lithium Manufacture
« Reply #5 on: 02/08/2012 07:36 PM »

I think AL-LI gears would be a lot more durable than wood or plastic.


Depends on the plastic.  Also, what is the duty cycle of the gears, how often are they in use, RPM, loads, etc.

I've been toying with Paul Spudis's New Lunar Architecture since last summer and only last week I managed to get a 60cm skydish to follow the sun and I managed to melt a floppy disk and burn a piece of wood with it. The idea was if you could make a foldable, light package that you could send to the moon and unfold it there to turn sunlight and moonrock into AL-LI sheets somehow you could robotically produce your own Earth Return Vehicle on the lunar surface, reducing the size of your earth to moon vehicle in the future.

I've built a system but it is heavy and cumbersome. The gears RPM is 1 cycle every 20 minutes to accurately point the dish at the sun. Here on Earth I'm fighting winds so I've over engineered my gearbox with a 35mm steel pinion gear going onto a 155mm solid steel gear mod 1.25. The dish/sensor weighs 4kg and with a materials processor at the focal point it may be as high as 10kg.
If  could manufacture dishes out of AL-LI it would reduce the weight
If I could produce Al-Li from old phone batteries and bean cans here on Earth first somehow it would prove this concept could also be done on the moon.
I'd like to know how this material could be made from recyclable materials as well as from rock dug up out of the Earth to maximize ISRU.


Offline Jim

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Re: Aluminium Lithium Manufacture
« Reply #6 on: 02/08/2012 07:47 PM »
Al-Li is not a ISRU material.

Offline zaarin

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Re: Aluminium Lithium Manufacture
« Reply #7 on: 02/08/2012 07:57 PM »
Al-Li is not a ISRU material.
No, but could it be made from lunar regolith?

Offline Jim

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Re: Aluminium Lithium Manufacture
« Reply #8 on: 02/08/2012 08:14 PM »
Al-Li is not a ISRU material.
No, but could it be made from lunar regolith?

No, because of the other metals involved.  But why are you focusing on it, just use aluminum, there is no need to save weight. 

Offline Tcommon

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Re: Aluminium Lithium Manufacture
« Reply #9 on: 02/08/2012 08:35 PM »
I've built a system but it is heavy and cumbersome. The gears RPM is 1 cycle every 20 minutes to accurately point the dish at the sun. Here on Earth I'm fighting winds so I've over engineered my gearbox with a 35mm steel pinion gear going onto a 155mm solid steel gear mod 1.25. The dish/sensor weighs 4kg and with a materials processor at the focal point it may be as high as 10kg.

Li-Al manufacture involves at least two highly reactive elements. The alloying formulas require accuracy to get the precipitation hardening right afterwards. It's probably not worth your time. If you want to try aluminum use scrap automotive castings - they are usually silicon-aluminum alloys with excellent mechanical properties that can be remelted with no ill effect.

What is your tracker design? Equatorial? A non-equatorial mount might handle the wind loads better because you can space the pivots differently.  Non-equatorial mounts can be driven with a simple tracking circuit and two drivescrews.


Offline Patchouli

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Re: Aluminium Lithium Manufacture
« Reply #10 on: 02/08/2012 08:56 PM »

Gears not a task for AL-LI, there are durability issues.  look at other aluminum alloys.

I think AL-LI gears would be a lot more durable than wood or plastic.

Nevertheless, could you suggest another lightweight material more durable?

I suggest looking into using multiple materials such as a plastic hub and a metal ring gear.
Standard high silicon aluminum alone probably would get the weight savings you'd want if you design the gears right.
Ie make them open like a bike sprocket vs solid.
Though since it's low speed you could look into using a linear actuator which uses an acme screw vs a spur gear drive.
« Last Edit: 02/08/2012 09:00 PM by Patchouli »

Offline zaarin

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Re: Aluminium Lithium Manufacture
« Reply #11 on: 02/08/2012 09:30 PM »

Gears not a task for AL-LI, there are durability issues.  look at other aluminum alloys.

I think AL-LI gears would be a lot more durable than wood or plastic.

Nevertheless, could you suggest another lightweight material more durable?


I suggest looking into using multiple materials such as a plastic hub and a metal ring gear.
Standard high silicon aluminum alone probably would get the weight savings you'd want if you design the gears right.
Ie make them open like a bike sprocket vs solid.
Though since it's low speed you could look into using a linear actuator which uses an acme screw vs a spur gear drive.
Funny you should mention that, I've tried the screwthread idea and it works but with a limited arc of only 20 degrees. Should such a system go to Shackleton crater of the moon it needs to spin 360 which a spur gear drive can do!
I've experimented with epoxying CDs together and filing them into spur gears and I glued 10 cds together with araldite and they still snapped under load. The steel shaft with the steel gears was strong enough and stood the test of time, however beltingonline does not sell AL-LI gears.
I understand this material is very light, very strong and can be made with heat (when smelting) than steel.
Assuming you wanted to turn regolith into another solar furnace (von neumann approach) you would necessarily need to make it out of the same material, however getting stuff to the moon is costly per lbs weight. The lighter I can engineer this system, the larger the dish, the more sunlight I can use to process materials with in less time. I mean even if I could get a 600kg robot package to the moon, that package has to be able to self replicate. Before I even think about the moon, I need to show that solar furnaces can be used here on earth first to make parts.

With the temperature I can probably burn bean cans. If I made a vaccuum chamber with a transparent side I might be able to melt them without oxidation.

I can see that on the moon oxidation won't be a problem thanks to its negligible atmosphere.

But say I could extract the lithium from batteries, aluminum from bean cans, zirconium from???? Could I use the heat of the dish to make an AL-LI part?

Here's my dish

And here it is following the "sun"
 

Offline DMeader

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Re: Aluminium Lithium Manufacture
« Reply #12 on: 02/08/2012 11:15 PM »
If you try any of this, I suggest that you stand well back because the fire and other pyrotechnics will likely be spectacular.

I also suggest that you are wasting your time. For a structure on the order of the shuttle ET the weight savings with Al-Li was substantial. For a part the size of your gear, the weight savings would likely be miniscule. I'd think a regular aluminum part  (well-machined out to remove excess material) or something made from some of the new engineering plastics or carbon fiber might be suitable. Don't be fixated on a particular material as you seem to be.
« Last Edit: 02/08/2012 11:21 PM by DMeader »

Offline kevin-rf

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Re: Aluminium Lithium Manufacture
« Reply #13 on: 02/08/2012 11:37 PM »
Speaking of which, considering how well both Al and Li burn, I have always wondered, how easy is it to get AlLi burning? As easy as Li, or a bit more difficult like Al?

Personally I would use a much lighter brass gear with excess materials removed. It is durable, easy to machine, does not burn, heavily used for gears, does not corrode, and weighs less than an equivalent Steel gear.

Ever notice climbers use Al biners and not steel ones... You can buy steel ones, they just weigh to much to lug around.
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Offline kevin-rf

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Re: Aluminium Lithium Manufacture
« Reply #14 on: 02/08/2012 11:43 PM »
Switch from wood to Al tubing, you will save a substantial amount of weight. Also you can get acceptable result by forming sheet metal into a reflector. It will be much lighter than the mirrors, actually come to think of it, buy an Aluminized mylar baloon fitted over the form will give you excellent results.
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Offline alexw

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Re: Aluminium Lithium Manufacture
« Reply #15 on: 02/09/2012 05:25 AM »
Personally I would use a much lighter brass gear with excess materials removed. It is durable, easy to machine, does not burn, heavily used for gears, does not corrode, and weighs less than an equivalent Steel gear.
     While I love brass, especially the sheer joy of turning it, how is a brass gear lighter than a steel one?
          -Alex

Offline Nascent Ascent

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Re: Aluminium Lithium Manufacture
« Reply #16 on: 02/09/2012 05:28 AM »
What about Delrin or glass-filled Delrin (acetal)?  It's used for gears all the time.  I don't know how Delrin is suited for space applications however.

Aluminum gears would work best if coated. General Magnaplate did a lot of coated aluminum parts for Apollo and other projects. 
« Last Edit: 02/09/2012 06:28 AM by Nascent Ascent »
“Why should we send people into space when we have kids in the U.S. that can’t read”. - Barack Obama

Offline zaarin

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Re: Aluminium Lithium Manufacture
« Reply #17 on: 02/09/2012 11:25 PM »
But I'm just splitting hairs...an interesting side note, Alcoa recently announced that it's ramping up it Al-Li output.


I emailed alcoa, thanks for the lead but they wouldn't sell me any AL-LI

I got this message "Alistair, I am afraid we are unable to provide an off cut of 8090 lithium. The price per kilo of this material would make £200 too small to saw down from any we had in stock.
Best regards - Hilary"

Offline Jim

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Re: Aluminium Lithium Manufacture
« Reply #18 on: 02/09/2012 11:33 PM »
But I'm just splitting hairs...an interesting side note, Alcoa recently announced that it's ramping up it Al-Li output.


I emailed alcoa, thanks for the lead but they wouldn't sell me any AL-LI

You don't need it, there are other materials out there.

Offline Enthalpy

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Re: Aluminium Lithium Manufacture
« Reply #19 on: 02/13/2012 03:05 AM »
Earlier Al-Li alloys like AA8090 did have Li as a main alloying element, improving density and stiffness a bit - a few percent.
Newer "Al-Li alloys" are Al-Cu alloys with traces of Li. They are minute improvements of Al-Cu alloys, which means that Al-Zn are better in many aspects, including weldability for some of them.

Weldalite and the like are as difficult to weld as other Al-Cu alloys, whatever the name may suggest. About as misleading as the "Al-Li" marketing name.

At and near the weld seam, crystals grow due to heat, as they do in any Al-Cu alloy, making the seam very brittle. One answer, for any Al-Cu alloy, is stir welding, where a rod rotates quickly in the hot aluminium to prevent crystal growth; this rod can provide by friction the welding heat.

Then, an alloy is chosen first for its capability: welding, corrosion, cold forming, surface treatment... Performance comes only second, especially as Lithium improves just a few percent. Tendency to seizure for instance precludes an alloy for gears.

Good gears are very difficult to produce. It's a complete company skill. Any attempt from a non-specialist will result in re-discovering why the materials not commonly used don't fit.

More, gears are very much a question of accurate shape and surface treatment, plus hardness and lubrication, so a smaller steel gear weighs less than a bigger aluminium one.

For long duration gears, only steel and few polymers like polyamide fit, with elaborate surface treatment. Aluminium is only for robot toys.

Offline M_Puckett

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Re: Aluminium Lithium Manufacture
« Reply #20 on: 02/13/2012 03:36 AM »
Aluminum is more of a metal for structure than for moving parts.