Mystery Metal

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tornitore45
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Re: Mystery Metal

Post by tornitore45 »

Continuing with sorting and classifying
When I saw a few shiny pieces of round stock I thought "oh goodie some SS" then as I pick them up they felt way too light to be SS
They shine like SS but do not have that yellowish tinge
Density range from 4.72 to 4.9 average 4.77 by the "lab grade" kitchen scale.
Looked up Titanium density turns out to be 4.5.
Considering Titanium is often alloyed with higher densities Palladium and Molybdenum, I thing I have some Titanium alloy.
My pleasure will evaporate as soon as try machining it.
Mauro Gaetano
in Austin TX
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Harold_V
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Re: Mystery Metal

Post by Harold_V »

Hmmm. Alloyed with palladium?
That came as a surprise to me, so I did a little research, only to discover that it's true. I'd not enjoy paying for the alloy, however.

There was a time when palladium was quite affordable. In fact, I can remember when it was only about $30/ounce. That day has passed, as it is now used in catalysis, where there is a huge demand. It is also used in jewelry, as well as dentistry (dental alloys was my primary source when I refined, although it was occasionally found in white gold, which is normally alloyed with nickel instead). Not being very abundant on this planet, it is not cheap. In the not too distant past it was well over $2,000 per troy ounce. As of today (6-21-20) it is down to $1923.00/ounce, and has had a value ranging in the hundreds of dollars and beyond per ounce for quite some time now.

I gathered that the titanium alloy using palladium is most likely not commonly found.

Titanium is not fun to machine, in spite of the fact that it appears to machine well.

H
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Steggy
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Re: Mystery Metal

Post by Steggy »

Harold_V wrote: Sun Jun 21, 2020 4:42 pmTitanium is not fun to machine, in spite of the fact that it appears to machine well.
You need a shipyard-sized lathe to turn a 1" piece of titanium. :D
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Harold_V
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Re: Mystery Metal

Post by Harold_V »

Heh!
I contracted to run three titanium pieces for another machine shop. This was many years ago, no fewer than 40. It was an enlightening (and not pleasant) experience. The project was primarily lathe work, with some finish work on the mill (a 3/4" hex broached, and a couple of ¼-28 holes drilled and tapped).

What I learned is that titanium machines quite well. Things run quite smoothly until the don't, and that interval of time must be something like a second, because inserts (turning) went from cutting without issue to broken almost immediately. Same with tapping the holes. The tap cuts, then it stops. Once it stops, nothing will cause it to cut again. A new tap in the same hole offers risk of ruining the tap. I managed to finish (and sell) the three pieces. How, I do not know.

What's interesting is that inserts of today are so much better that they are running titanium @ 400 sfpm, which would have never worked in my day. However, the performance of the inserts is well measured and they are typically changed by the amount of time in operation. I suspect that I'd do much better today than I did those many years ago.

Broaching the hex was a nightmare (work hardening and deflection), as it was stroked with a 120°form tool with a .062" radius. I had five thou tolerance and needed every bit of it. Not the way I liked to work.

I have machined titanium only a few times since that experience. I'd rather avoid it.

H
Wise people talk because they have something to say. Fools talk because they have to say something.
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