Thread: How do I tell if it's aluminium?

As Schtoo said zinc is noticeably heavier than aluminium.
Compare a bit of ally to say a car door handle and you'll soon see the difference.

I don't think it matters a great deal. If your scrap is castings, and they look and weigh like aluminium, you're probably good to go.

I'm looking at my 1959 Handbook of Chemistry and Physics, Table of Composition and Physical Properties of Alloys. Specific gravities range in the neighborhood of 2.7 to 2.96, except Alclad (coated sheet) at 2.00, which is NG for casting anyway. Most of the casting alloys have some magnesium and/or zinc and/or other stuff. Alloy number scheme has changed since then, so alloy numbers might not help much. Some alloys with names are:
Lynite, piston: 95Al, 2Cu, 1.5Mg, 0.8Fe, 0.2Si, 0.01Mn
Lynite, piston: 89Al, 11Cu, 0.5Mg
Liberty pistons: 77Al, 21Zn, 1.1Cu, 0.5Fe, Pb, Sn
Sand-casting 214: 96.2Al, 3.8Mg
Sand-casting 195: 96Al, 4.0Cu
Sand-casting 355: 93.2Al, 1.3Cu, 5.0Si, 0.5Mg
Sand-casting 356: 92.7Al, 7.0Si, 0.3Mg
Sand-casting 220: 90.0Al, 10Mg
Sand-casting 112: 89.3Al, 7.5Cu, 1.2Fe, 2.0Zn

My Gingery books are still in a moving box, but IIRC (or maybe from some other book), you can even use beer cans or extrusions, but only for non-structural applications as they're entirely different alloys. Might not pour or solidify very well either.

Joe

Beer cans are a disaster, Not worth the effort unless you can squash them into a brick. The thin sides burn up and become slag/dross which just makes it a pain. Also need to make sure they are bone dry before putting them into molten ally or you end up with a small scale bomb. I have never had that happen, and don't plan to try it out.

Al foil has iron in it, but agian you need to squash it into a brick. Extrusions are pretty good and they come out of the sand nice and shiny.

In homebrew applications, the alloy isn't critical, just go overkill on thickness and you should be covered.

Silent, when you go scrounging for scrap ally, keep in mind things, like, Will it fit in the pot? Can you break it down without too much trouble? Is the stuff thick enough to melt down well or will it turn to crap?

I have found that old castings are excellent, as you would expect. Apparently pistons and gearbox casings are the best for almost anything since they cast well. Extrusions are good for general stuff, but you may get some problems, and don't ask too much of the casting.

If you find some good quality zinc based stuff, use it for when you need something with extra strength, since the good zinc alloys are much stronger than ally typically is. This doesn't include old car door handles though, they really are junk and should be treated accordingly.

And if you can melt ally, brass isn't too much further up in temperature.

Google is also your friend.

Surely a filing/ cutting/ scraping test would give some indication.

I seem to think that good ally tends to clog files & stuff more redily than zinc.

What about alook at the broken edge.


Dead alloy wheels aparantly are the best quality source of casting material.

A mate of mine used to do the rounds of several local wreckers for casting material....he prefered wheels.

there is a lot of good aloy in modern cars too if you go looking for it.

cheers

OK, all good stuff. Thank you. I'm not quite ready to melt yet, waiting for the weather to cool down a bit. It just came up because I got access to all these old pumps. I'll toss them in a corner and wait until I know more about what I'm doing. Cheers!!

I'd do this outdoors, because any of them can burn.

A propane torch will easily melt zinc. You might even get away with an electric soldering iron.

It will take a very long time to melt a piece of aluminum any thicker than a beer can, and the electric soldering iron probably won't touch it. Magnesium is also high melting. You might catch a thin ribbon of it on fire with the propane torch, but an electric soldering iron shouldn't faze it.

Outdoors is key. If you were here, I'd offer that American pennies are made of zinc, and that would give you a certain piece of zinc to test against.

R. K.

I'd offer that American pennies are made of zinc

I'm happy to receive a few to experiment with. I reckon a tonne or two to start with

But seriously, I thought they were some copper-based alloy or something? I remember putting one in a machine at the Empire State building and it squashed it flat and stamped a tourist message on it.

Originally Posted by Schtoo

Al foil has iron in it,

Not if you buy "Comalco" its 99.97 aluminium , we use it at work to make custom blends of lead... its the cheapest way of buying it per K.
Your casings would prob be a aluminium zinc alloy, aluminium by itself is too soft so they add zinc to harden it also lowers the melting point of aluminium, if the pumps were made to be portable it would contain a high percentage of magnesium.
I know pure zinc melts at 420C and aluminium/magnesium is about 700ish depending on whats blended in it, its very rare for these metals to be in pure form.
As to refine them to a 99.99 product is super expensive... even our 9999 lead cost about an extra 1~2k per ton to produce(its what I actually do) we add magnesium and calcium and put it through a KBA(Kroll Bereton Antimonal, or some thingo)process.

Oh and steer clear of melting high content magnesium or product that contains calcium unless you study and use correct safety procedures to handle it.(espes cal it makes a very very nasty gas if exposed to moisture)

Here bookmark this page handy for a reference

Okay, dont want to get anyones nose out of joint but theres only one true way of finding out a materials composition. That is to carry out an electrical burn on the surface and analyize the smoke composition to find out what its made up of. For average joe blow its not worth it as it costs 350 per burn here in australia. The next easiest way to find out what type of broad spectrum the material is made out of is a conductivity test, this will only tell you what the majority of the material is made out of. If its aluminium itll be around 30% + IACS "international annealed copper standard" unless its an aircraft grade aluminium and then it could be anything so it would require an additional hardness test as well, if its zinc itll be 25% Iacs, and magnesium will be around 15%. If your willing to pay postage to perth and back break a small piece of and Ill tell you what base compound it is. This is what I do for a living test and examine metals fitted to aircraft for cracking distortion overheating hardness ect
Steve

Simso,
You won't get many of this lot spring that amount of money for a good welder let alone an Metals ID test.A spectrograph analyser is a great but pricy bit of kit.

Hear the squeeking sound here doncha? They are as tight as a fishes what not .

Here is the electrical test that I did to confirm that the Makita belt sander alloy casing had zinc.I know for sure that it can't be TIG welded. One arc and it flashed off with heap off white smoke. Die cast YUCK!

Grahame

Yeh I know, but Im happy to put the offer out there, it takes me less than a minute to do a conductivity test on something and about another minute to do a hardness test. And thats good enough to give them a base material idea.

Originally Posted by silentC

I'm happy to receive a few to experiment with. I reckon a tonne or two to start with

But seriously, I thought they were some copper-based alloy or something? I remember putting one in a machine at the Empire State building and it squashed it flat and stamped a tourist message on it.

If you PM a mailing address, I will send a few, but the postage on a tonne would be prohibitive. Zinc's lousy casting metal anyway.

I just found out that it's only since 1982 that they're made out of zinc. I had thought they were plated zinc since about 1959, when they changed the reverse design from wheat to the Lincoln Memorial.

R. K.

I think that pennies are the ones that are now worth more as scrap/base metal than they are as currency. Not sure about that, but I suspect it is/was probably true.

Simso, it doesn't really matter what the stuff is for this kinda thing. If I was building a plane, then I wouldn't need to test it since I'd buy the right stuff from the get-go.

I use whatever ally I can get my grubby hands on, and I don't care what it is, so long as it does what I want it to. If it doesn't, then it cost me about $1 in kerosene or waste planer shavings, depends on what I am doing.

It would be nice to know what's what, but it's just not that important.

If you PM a mailing address, I will send a few

Haven't you heard about Australia Post! They'd never make it to my door!!

Thanks for the offer though mate.

Thanks for the offer also simso. As Schtoo says, it's actually not all that important for my purposes. I've only got three of these pump covers and I'm likely to be collecting all sorts of stuff to throw in the pot.