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janvanruth
12-20-2014, 03:38 PM
Is there a quick and easy way to distinguish between brass and bronze?
The colour is no different to me.

brian Rupnow
12-20-2014, 04:08 PM
A generalization perhaps, but--If you machine brass you will get normal (but small) chips. If you machine bronze you will be bombarded by very hot powder.

boslab
12-20-2014, 04:50 PM
And old fashioned test was to rub the dickens out of it with your thumb, then smell!, if you smell metallic then it's brass, if not it's bronze, I would advise trying it out myself, I never have as I either have some brass or bronze as I tend to buy it, then stamp the end, I'd never figure out what the hell anything is otherwise, I don't have a XRF spectrometer at home!, although I did have one in the shop for a while as I was repairing it for TATA, think it's still in use.
Mark

cameron
12-20-2014, 05:03 PM
There are too many different brasses and bronzes to generalize. Silicon bronze, gun metal, aluminum bronze, Tobin bronze ( which is brass!), Beryllium bronze, Naval brass , and on and on.

Richard P Wilson
12-20-2014, 06:02 PM
The only way I know, rough and ready though it is, is to drill a sample. Brass comes out in chips, bronze comes out in curly lengths.

loose nut
12-20-2014, 07:29 PM
Fresh cut bronze has more of a gold colour. Not very scientific but if you see brass and bronze side by side then it might help.

janvanruth
12-20-2014, 07:49 PM
Now i really am confused.
Machining bronze will give long curly lengths, drilling it will give very hot powder?

To be more precise: i need to make a bearing/bushing out of bronze.
I have gathered several pieces of brass/bronze over the years but dont know wat it is.
All i want, is to find in my collection a piece i can make that bushing out of.

I know brass will turn red after exposure to acids like in brazing with flux as the zink is drawn out of the alloy by the acid.
Will a bronze suitable for making bearings also turn red after exposure to an acid.
If not i will simply perform a test with acid.

J Tiers
12-20-2014, 11:42 PM
Simple answer is..... try all your pieces.... them what does is brass. Them what doesn't is probably bronze, but at least is not brass.

bearing bronze is not necessarily the same as naval bronze, or any of the other umpteen types, so even if you end up with a pile that says "probably bronze" on it, that may not necessarily mean it will make a good bearing. Does your drawing call for any special type of bronze?

PixMan
12-21-2014, 12:08 AM
Here's a website that may help narrow it down...or not. Depends upon the color balance of your computer monitor.

http://www.metalreference.com/Forms_Copper_Alloy.html

LKeithR
12-21-2014, 01:04 AM
If you need a specific material for a job the only way to guarantee you've got it right is to have traceability to the source--anything else is just a guess. One of the joys of playing with "mystery metals"...

macona
12-21-2014, 02:31 AM
Take it to a scrap yard with a XRF gun and see if they will tell you what it is. Im picking some LN2 up for my EDX on my SEM, if it works I can take a tiny sample and tell you what the composition is.

LKeithR
12-21-2014, 02:36 AM
Take it to a scrap yard with a XRF gun and see if they will tell you what it is. Im picking some LN2 up for my EDX on my SEM, if it works I can take a tiny sample and tell you what the composition is.

Somebody care to decode this for me? I haven't got a clue...

Richard P Wilson
12-21-2014, 03:50 AM
[QUOTE=janvanruth;954860]Now i really am confused.
Machining bronze will give long curly lengths, drilling it will give very hot powder?

No, I said that drilling bronze will give long curly lengths. Someone else said that machining (whatever that means, drilling, turning milling?) will give very hot powder, although I must admit that isn't my experience of it, apart from when machining sintered bronze bushes.

If you are planning to make bushes anyway, why not chuck a few pieces and try a drill on them?

boslab
12-21-2014, 07:55 AM
An XRF in a contraption called a X-ray fluorescence spectrometer, it hits target sample with X rays then looks at the characteristic energy spectrum of what's being exited, handy little ones found in scrap yards, and it appears pawn shops in las vagas!, hi tech when I was there!,
An SEM is a scanning electron microscope, which our Macona is the resident expert on, I've played with XRF, and a little on them but he's the go to guy
OES is another analyser, optical emission spectrometer
Mark

lynnl
12-21-2014, 09:09 AM
I suspect the comment "...turns to powder when machined.." is in reference to oilite bronze bearings.

Fasttrack
12-21-2014, 12:10 PM
Somebody care to decode this for me? I haven't got a clue...

XRF - X-Ray Fluorescence

LN2 - Liquid Nitrogen

EDX - Energy Dispersive X-ray

SEM - Scanning Electron Microscope

The XRF works by shooting some X-rays at the surface and looking at the resulting emission spectrum. Just like visible light is reflected and absorbed in a characteristic way, so to are X-rays. You can determine the elemental composition of a material this way.

The EDX is basically the same principle, but it uses a beam of electrons from the SEM to excite the sample and cause emission. The emission spectrum is then analyzed and the elemental composition determined.

brian Rupnow
12-21-2014, 01:12 PM
Lynnl--No, I am talking about 660 bronze when I say "bombarded by red hot powder".--Brian