950 Palladium: A Seamless Operation for Bridal Products

The John C. Nordt group supplies raw materials and components as well as finished bridal products. This article features their process for manufacturing 950 palladium seamless tubing, referred to as pipe.

By Mark B. and Lainie Mann -- JCK-Jewelers Circular Keystone, 1/1/2008

These wedding bands were created by Guertin Bros., a division of Nordt. They are seamless and made from 950 palladium extruded tubing that has been alloyed with ruthenium, another platinum group metal. The extrusion process forms pipes of metal with a fine-grain structure and increased Vickers hardness. For consumers this translates into longer wear over comparable palladium products that have been made using traditional lost wax casting methods.
The pattern or design on each piece is deeply cut into the metal by computer-controlled lathes and cutting machines. Because of the varying factors of time, labor, and material for each of its designs, Guertin Bros. prices its product by the piece and not by weight.
Melting the Metal and Pouring the Billet
The process begins by melting small particles of 950 palladium at 3,000 F. The molten metal is then poured into a large cylindrical mass called an ingot or billet. Each billet weighs 175 troy ounces. Palladium absorbs oxygen when molten, so melting is done inside a sealed chamber of the machine featured in this image where the atmosphere is first vacuumed out and then back-filled with a cover gas prior to melting. Induction heating is used to melt the small particles of metal that are contained in a zirconium crucible. After melting, the metal is poured into a copper ingot mold and allowed to solidify in the chamber under protective cover gas.
Machining and Core Drilling the Billet
Next the billet is mounted on a computer-driven lathe, which drills a core and machines the outside to an ultrafine surface. This image shows a machined billet covered with a water-soluble lubricant.
One of the drills featured in this image performs the core drilling. The size of the drill depends on the ultimate finger size of the wedding bands that will be made from the extruded tube.
The Results
This image provides examples of the featured process. Shown are freshly poured billets, machined billets that have been core drilled, and extruded tubing or pipe. The piece closest to the foreground is 950 platinum. The freshly poured platinum billet weighs well over 300 troy ounces. The billet in the background is 950 palladium
and weighs 175 troy ounces. The billets are of exactly the same volume but the difference between the densities of the metals has the platinum weighing in at nearly twice as much as palladium. Note that the platinum example has a shiny finish while the palladium billet shows the bluish surface oxidation characteristic of palladium after heating. Both metals will have a lustrous finish after machining and drilling.
Hot Extrusion
Hot extrusion is the first step in the process of making seamless tubing from the billet. The billet is heated to a very high temperature and then placed on a platform just below the yellow and black diagonal lines with a central opening that holds the die below. The large multiton press above the diagonal lines is then started downward, forcing the heated billet into the extrusion die, which reduces its diameter, compresses the molecular structure, and elongates it from its original 10-inch length upwards to 4 or 5 feet. The ultimate length of the extruded tube depends on the final diameter.
Cold Drawing the Billet
With the tube extruded, it is then cold drawn. One end is slightly tapered so that it can be forced and pulled through the forming dies to achieve its specified dimensions. This extrusion process is done under significant pressure and condenses the molecular structure of the metal, making it harder with each pass through the series of dies that reduce its dimension. No annealing is done to palladium during this process.
This cart is stocked with extruded and drawn palladium tubing of various inside and outside diameters. These pipes will be cut into specific widths to fill orders. The cutting is done on a computer-controlled lathe using polycrystalline diamond tooling and water-soluble lubricant.
Forming Wedding Bands
Each part produced by the Nordt companies requires a different series of machining strategies and finishing techniques. Here a five-axis mill shapes a palladium wedding band and engraves the intricate detail.
The Nordt Factory
Nordt's array of specialized equipment is housed in a 35,000-square-foot manufacturing facility. The company follows ISO 9000 quality requirements and hopes to be certified within this internationally recognized system soon. Its computer-aided-manufacturing equipment can engrave patterns, cut bands to length, add texture, and apply a variety of detail. The area shown in this image houses approximately 25 workbenches where the manufacturing detail—such as stone setting, application of certain finishes, and laser joining—is done by hand.
Leading the tour of the Nordt manufacturing facilities were [from left] Wayne Flippen, general manager; David Skuza, vice president of sales and marketing; and Paul Nordt, CEO. A large part of the tour was also conducted by Clark Hill, director of metal fabrication, who oversees much of the manufacturing process. Hill also works with Phil Weeks in the company's metallurgical lab doing Vickers hardness testing and other analysis of product to ensure quality and consistency.

Sizing a Seamless Ring

Retailers can easily increase or decrease the size of a seamless palladium band made from the featured process by using a ring stretcher. Here Clark Hill, Nordt's director of metal fabrication, demonstrates increasing the size of a standard flat palladium band. He takes it from a size 10 to a size 13 by working it on the expandable mandrel of the stretcher. Hill braces the band with one hand as he pulls the lever incrementally, careful not to stress the metal. He limits the amount of each expansion to about a quarter of the overall size increase, rotating the band 90 degrees on the stretcher after each pull until the desired size is achieved.

If stretching a band is not an option, the Nordt companies will take an order and produce one ring (average two-day turnaround) to the exact size required for the sale. They offer to work in half-size increments.

Note: Since ring mandrels vary and are typically available only in U.S. measurements, workers at the Nordt companies measure the ring size using calibrated micrometers and take an inside diameter measurement. They have an international sizing chart that shows the inside diameter measurements and the ring-size equivalent for several different countries.

The John C. Nordt Group

The John C. Nordt group of companies, headquartered in Roanoke, Va., consists of five divisions that work with the jewelry industry at all levels.

Nordt develops products for manufacturers, designers, and wholesale companies based on their specifications.

Guertin Bros. works with retailers to design and produce finished products, which may be branded under the specific retailer's store name.

J.C. Nordt Far East focuses on manufacturing in the United States for Asian companies.

Nordt Linear Technologies produces seamless tubing for jewelry and several other industries such as medical, musical, and aerospace.

Per Amoré designs and develops a line of finished wedding bands.

Frequently Asked Questions

I recently did a custom ring in palladium. I carved a wax and then had it cast. After casting and prefinishing, I could not drill holes in the mounting to flush set gemstones. What was the problem?

For casting, wax models are placed in investment molds. The wax is eliminated and the palladium is cast into the voided area. Some casting facilities allow the flask of cast palladium to air cool. After that, they bead blast the cast pieces to finally remove the investment material. This bead blasting and other processing methods for cast palladium products can significantly increase the surface hardness of the cast piece. To make the cast piece workable, the ring should be annealed.

To anneal a palladium piece, place it on a high-heat soldering block. Use a direct flame from a propane or natural gas and oxygen torch to heat the ring until it's bright orange. Then raise your torch up and hold it at this temperature for 20 seconds. Allow the item to air cool. After cooling, the body color should appear to be oxidized, as shown in this image. If it is not oxidized, it is not annealed.

Note: Pickling in Sparex or buffered sulfuric acid will not remove the oxidation as is common with gold. Use a neutral or reducing flame (a flame with equal amounts of gas and oxygen) to remove the surface oxidation. The piece will become a dull silvery white. To brighten, place the ring in a magnetic finisher for 20 minutes. The piece will then be ready for polishing and finishing.