metal for moulding toys and the like

I have a few old French ocarinas (see the ocarina page on my site for a picture of one) which seem to be moulded out of a similar
metal to that used for toys. Whatever it is, it's not ferromagnetic. As they've lasted 100 years without bending or breaking, I assume it's something tougher than the usual toy metal.
Anybody know what these alloys are?
And why are they used at all? Surely iron is the cheapest metal they could use?
My pet beef with this stuff: an inferior grade of it is used for the legs of clarinet stands (the sort where the legs fold into the cone). They break very easily. I first found out how brittle it is when I was playing in a pub and a glass fell off a table and landed on the leg of the stand. The glass stayed intact but the leg shattered. On average I break a stand leg every few months.
==== j a c k at c a m p i n . m e . u k === <http://www.campin.me.uk ===Jack Campin, 11 Third St, Newtongrange EH22 4PU, Scotland == mob 07800 739 557 CD-ROMs and free stuff: Scottish music, food intolerance, and Mac logic fonts ****** I killfile Google posts - email me if you want to be whitelisted ******
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They probably are zinc alloys. The bottom-end alloys, which are remelts of various scrap, are known as "pot metal" in the US. I don't know what they call it in the UK. The high-end alloys are varieties of Zamac, which are based on zinc with 4% aluminum, plus other additives for different performance characteristics.
Pot metal is very brittle; Zamac, much less so, and its strength approaches that of mild steel (around 52,000 psi yield in tension). But it is much easier to melt and cast than iron. Its melting range is on the order of 380 deg. C (725 deg. F). It's one metal you can cast at home without a lot of elaborate equipment.
--
Ed Huntress



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Jack Campin - bogus address wrote:

As Ed said, most probably pot metal, aka white metal. The alloy can vary widely as far as the element percentages, causing large differences in quality.
...

Well, RCM was the right place to come: "We're RCM, we make stuff from metal". IOW, tell us about your stand legs & we'll tell you how to make better ones.
Bob
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On Wed, 30 Sep 2009 17:30:04 +0100, Jack Campin - bogus address

Given the age, they might be pewter. Pewter has a low melting point and it's very fluid when molten so it can retain very fine decorative detail in castings.
Pewter is an alloy comprised mostly of tin with varying amounts of antimony, copper and (in very old pewter) occasionally lead. It's been in use since about 1500 B.C. One lead-free pewter alloy is known as Britannia metal.

The much lower melting points of white metals permits die-casting in reusable molds as opposed to the sand molds usually used to cast iron. The lower temperature alloys also require considerably less time and energy to melt the metal.

White metal has accquired a bad reputation partly because it is so amenable to making very cheap high-volume goods. It can be die-cast in reusable molds with a high degree of automation while iron is usually sand-cast in single-use molds. Another way to reduce cost of goods is to reduce the amount of material used, and white metal can be successfully cast in quite thin sections. The result was that some products use so little metal that they're not strong enough for their intended purpose, just strong enough to sell.
White metal has largely been supplanted by die-cast aluminum in recent years as we've learned how to die-cast ally successfully and well. Part of that may be due to increased ability to economically machine reusable molds out of robust materials with CNC machinery. Zinc-based white metal can be noticably stronger than ally (though not as ductile) but it's also heavier and costs considerably more. I know of one semiautomatic pistol from a very well-known mfr that was (maybe still is) made with a white-metal slide. Not something I'd want to own, but it was/is very inexpensive as such things go.
Products can be and are designed with aluminum castings with more attention to low cost than to long robust service, with not quite enough metal to do the job well.
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Very well described, Don. I'm frequently impressed at small precision castings with small features, used in light duty mechanisms. The obvious advantage to many small cast metal parts is that the same parts, if produced in various plastic materials, would fail quickly.
The "pot metal" castable alloys generally stand up well to light load/force duties, although many products made primarily from these alloys aren't very reliable.
--
WB
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On Sep 30, 10:30am, Jack Campin - bogus address

The only music stands I've used have either had real cast iron bases (school) or were bent and plated sheet steel(home). It would take a pretty hefty glass to break either...
Your ocarinas are probably a mostly-zinc die casting alloy. I have an old book from the era, they were just exploring using steam for pressure casting at the time, previously they only used gravity casting. Pressure casting let the designers make their parts thinner. Iron is so much hotter, needs sand molds or some really exotic alloys for permanent molds. The zinc-based white metals are low lemperature stuff, castings can be made about as fast as the dies can be cycled. There's hundreds of alloys, some are fairly high strength, several times that of grey iron. Atlas used to crow about the strength of their die-cast change gears on their lathes, not saying that after several decades they tended to crumble. Phase- change will do that. Then there's my old LTD window handles which lasted forever, but the steel rivets for the knobs gave up the ghost.
Are your ocarinas cast as one piece or in halves and joined somehow? With die-casting, there's really no way to have a core with a totally enclosed item, I was just wondering how it was done. And do they sound different than the ceramic items?
Stan
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Seem to be two-piece - there's a polished line round the join. Very neatly soldered or welded.

Yes - I prefer the sound of the ceramic ones; and the ceramic ones seem to be easier to play in tune, for reasons I haven't worked out. Whether anybody but the player could tell them apart I don't know. The sound is so exotic these days that audiences just react with "wow, what is that thing?". (I usually play Scottish music on them; they were last in common use as a folk instrument in Scotland about fifty years ago).
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On Fri, 02 Oct 2009 10:27:32 +0100, Jack Campin - bogus address

That might again suggest that they're made of pewter. Zinc-based whitemetal does not lend itself well to either soldering or welding. It can be done, but it wouldn't be a viable production process. Pewter, on the other hand, is very amenable to soldering.
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Believe it or not, 'pot metal' was used by Gibson for tone rings on their very expensive banjos during the 60s and 70s. They also used it for the one-piece flanges which replaced the old tube-and-plate flanges of the early Mastertones. Some of those late '60s RB-250 'bowtie' inlaid Mastertones sounded truly dreadful with their pot metal tonerings, 6 ply gumwood shells and any other tricks they could come up with to cheapen the things.
KH

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