Shear Strength of Gold

OK send me some samples and I'll do some measurements for you

Seriously though:-

http://en.wikipedia.org/wiki/Gold

Has shear modulus = 27 GPa

Does that help?

Yes I come across the modulus, the modulus is shear stress vs.shear strain (if i'm not mistaken)...still there is no shear strength

by the way...i myself doesnt own any sample!

If you are punching, shearing, or cutting it, then the shear strength would matter.

If you are bending it, rolling it, or die-stamping it, you need to deal with bending, tensile, and/or compressive strength.

in one website (forget what its name), theoretically the formula :

i.Stamping without shearing :

perimeter x material thickness x shear strength = required tonnage

ii.punching:

required tonnage for stamping x shear factor

both need shearing value...where should i get it..?

The answers that you seek will greatly depend on the Karat of the Gold......how much of an alloy it is.

yes, it should be...but cant i just get an approximate value for preliminary calculation using above simple formula, just to have an idea? do you have any figure?

Young's modulus of elasticity values will vary depending on the metals used in the alloy. Gold is typically alloyed with other metals to increase its strength and hardness, since pure gold is already remarkable for its high ductility and malleability. Some examples are given here:

http://www.keytometals.com/page.aspx?ID=CheckArticle&site=ktn&NM=230

Also note that the strength of any gold alloy will vary the most, depending on whether it is annealed or hardened - see the chart at the bottom of the page. The usual process is to anneal the gold sheet before stamping. The process of stamping will harden the metal to some extent, but additional treatments may be required if the end product is to retain its shape without deformation.

thanks for the link...it does enhanced the knowledge but still doesnt have any shear strength value given

Can you first detail why is this so important. If it is just from your personal knowledge then it will be a waste of time.

my team want to buy a hydraulic press to stamp a gold sheet whether making it into coin or souvenir. i have ask some press machine supplier, they require us to provide what exact press tonnage we want.they do suggest some tonnage range but i want to know exactly how they determined.so i googled and find in one website the formula which require shear strength value to be use to have the pressing tonnage.we can find the value for steel but not gold.

i dont know whether this is so important or not but i'll much appreciate if i can have the answer.

Send them the sample and tell them this is what you want to do.

I happen to drive back & forth Toronto to NY. On way at Coffee Stops in USA Highways, there are manual (with handle) machines that takes in your dime and stamp out any engraved photo and bringing out the coils in an oval shape for souvenirs kids would like to have. I do not find any complexity in this machine simple-manual with hand-wheel.

Send them the samples and ask them what you want.

coins in oval shape ( the dime comes out as)

The press operation being described is known as "coining," and it takes more force than punching, shearing, or bending.

Well... stamping a cut blank is "coining", but cutting the blank itself is "blanking" (not punching). These are two distinct operations requiring a different machine. There are also several steps between blanking and coining, in which the surface of the blank must be finished and polished before coining.

The OP isn't clear whether they intend to cut their own blanks and then stamp them, or whether they have idly assumed that a coin is made in a single blow operation.

It also isn't clear to me, why someone with the resources to engage in a mechanized gold coin minting operation would be asking for free information on the internet, instead of engaging the professional services of a goldsmith.

Consider all comments with respect to variations due to alloy type. If you have the yield limit for the alloy divide by 3^0.5 and you obtain the approximate value for the shear limit.

GA.