Milling Platinum Sterling (A New Alloy)


One of the major reasons for attending Kraftwerks is to learn what is new in the industry. This year was no different. Milling Platinum Sterling (925) – A New Alloy

Milled metal and billetA billet of Platinum Sterling 925 (on the right in the picture) was milled out to .15 mm thickness (less than a playing card thick) with absolutely no annealing. This brand new alloy is called Platinum Sterling, and is mostly fine silver with a modifier of Platinum in it (4-6%). There is also a small amount of copper (a few %). At this point the alloy composition is still pretty much a secret because the refiner’s are still in the process of acquiring patents.

This year at Kraftwerks the refiners of a brand new alloy were there to demonstrate this new and very interesting metal.

The inventor of Platinum Sterling is Marc “Doc” Robinson, he is the guy running the mill. He is currently the Technical Director of Far East Operations at ABI Precious Metals. As a note of interest Doc was the original founder of Kraftwerks.

As you may guess this new alloy is going to be a major new thing in jewelry manufacturing and currently the Asian jewelry manufacturers are working heavily in this metal.

Note: There is a solder made for this new alloy, in case any of you jewelers were wondering.

This alloy is still brand new and there are currently only a few people/jewelers working with it in the USA. However the refiners did have casting shot of this alloy available for people to purchase and try for the jeweler’s that attended Kraftwerks. (Contact Info at end of article)

Note: Another good reason for attending Kraftwerks. Actually being there and talking to the manufacturers will often help you learn about new products and get you the opportunity to try some of the new products before anybody else.

Platinum Sterling has a very bright look to it and could be easily mistaken for white gold. Which is actually one of the uses this new alloy will really be used for in jewelry. It has the very bright white look of white gold and at just a small percentage of the gold cost.

This new alloy also has some other very unusual properties that make it unique. Both in casting (see my article on casting Platinum Silver) and in milling. It also has some unusual annealing and hardening characteristics.

For those of you who are not jewelers or metal workers annealing is the process of heating a piece of metal to help make it pliable and workable during the process of working, milling, hammering, et… of the metal. Annealing keeps metal being worked from becoming brittle and crystallized during the working process.

The Platinum Sterling pictured above was milled with no annealing during the whole process from a billet to the finished sheet of metal .15mm thick. Typically most metals would require several annealing stages during the milling process to get the metal that thin.

The milling process is interesting and because they did not have to anneal the Platinum Sterling, the milling was done in a very short time as compared to other metals.

Industrial millThis is a large motorized mill. As you can see it is quite a massive piece of equipment.

This mill is actually designed for a large scale operation, like a refiner or large jewelry manufacturer.

The blue can is a cleaning solvent for the actual rollers. The rollers are polished and need to be kept clean. Any mark or dirt on the polished rollers will end up on the metal being milled.

The left set of rollers is polished smooth and used for making sheet metal. The rollers on the left are shaped for making various gauges of wire. Also the rollers can be changed for other shapes and types of finished products.

Smooth rollersThe smooth polished rollers used for sheet metal.
Wire gauge rollersThe shapes rollers for making various wire gauges. Notice that the grooves get smaller as you work to the right. That is how the wire is milled, large to smaller.
Industrial mill, cleaning the rollersThe rollers in the mill are being thoroughly cleaned before any actual milling starts.

Like I said before, any dirt or marks on the rollers will be “milled” into the actual metals during the milling if the rollers are not clean and smooth.

Note: The gears on the top of the mill by his left hand. See the crank?

That crank is used to actually open and close the spacing between the rollers.

The rollers will be set at the wide position, just very slightly narrower than the thickness of the metal/alloy billet being milled.

The metal thickness is milled very slowly in small thickness increments. The reason for this is two fold.

The metals should not be stress any more than necessary at one time and also the billet would obviously not ft if the gap between the rollers is too narrow to start.

Platinum Silver BilletThe billet of Platinum Sterling alloy ready to be milled.

Like I said this billet is going to be milled into sheet metal.

If you wanted to mill wire, generally this billet would be cut into strips, if need be.

But better yet, when they refined the metal it would have been poured as molten liquid metal into longer more wire type shapes.

So that the shape of the starting metal would lend itself to wire gauge and the milling process could be started right away on the wire/gauge side of the mill.

There are a lot of ways these processes can be done and a lot of milling options. Just keep in mind simple is usually better.

feeding the billet into the millFeeding the block of metal into the mill.
getting the billet from the other sideRetrieving the milled metal from the delivery side of the mill.

Note: The mill will roll anything it catches including your hand. Safety is very important, in particular around the “feed” side of the mill.

Adjusting the gap of the millThe billet of Platinum Silver alloy ready to be milled again.

Notice that he is cranking down the gap between the rollers to make the metal thinner.

This process is repeated over and over again until the sheet of metal has reached the required thickness.

Milling this sheet of Platinum Silver did not take very long. The whole milling process/demonstration took about 15 minutes.

This metal was not annealed, because of some special and odd properties of the new Platinum Silver.

Most metals would take a lot longer because of the required annealing needed to make the them this thin.

Platinum Silver BilletThe billet of metal going into the mill.
The much thinner sheet of metal coming out of the mill.
Platinum Silver sheetThe sheet of finished alloy that was milled.

The original size of the billet was about 1/4″ to 5/16″ thick. So as you can see the metal was milled quite a lot.

For those of you who are jewelers. I would suggest that you contact the refiner/manufacturer of this interesting new alloy and try some.

I think this alloy may change the jewelry markets significantly.

Contact Info for Buying & Questions:
This is a patent pending product and owned exclusively by ABI.

Contact them at: Marc “Doc” Robinson
Technical Director
ABI Precious Metals
Box 11509
Carson, CA 90749
800-768-1566
310-768-1566 Fax
[email protected]com
[email protected]

About the author
Jeff R. Graham
The late Jeff Graham was a prolific faceter, creator of many original faceting designs, and the author of several highly-regarded instructional faceting books such as Gram Faceting Designs.
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