Machining rings around the competition

Tim Brosius has worked with hard materials, tool geometries and coatings since 1974. More than a decade ago, he owned a business that produced, among other things, short, cylindrical carbide dies that resembled finger rings. Today, Brosius is CEO of Tungsten Pride LLC, Minneapolis, whose sole business is manufacturing custom tungsten-carbide wedding, engagement and personal rings. “People ask, ‘Could you do one this way for me?’ and we say, ‘Yep, that’s what we specialize in. We make one ring at a time,’ ” Brosius said.

The video above prepared by Tungsten Pride provides an overview of the company’s ring production capabilities. Courtesy of Tungsten Pride.

Ring IDs generally range from ½ ” to 1 “, but can be larger or smaller. “If a guy wants to put a ring on an elephant, or if he marries a tiny girl, we are capable of doing it,” Brosius said.

According to Brosius, competitors typically grind generic carbide blanks to shape by the thousands, and jewelers sell them off the shelf. Tungsten Pride, on the other hand, produces its rings on a 2010 Mazak Quick Turn 150-II CNC turning center, machining them from 8 “-long sections of tungsten-carbide tubing. “We are the only ones in the world that do it the way we do,” he said.

Tubing ID and OD depend on the size of the finished ring. Ring walls typically are 0.083 ” to 0.098 ” thick; the larger the ring size, the thicker its walls. Ring width varies depending on customer desires, but a typical width would be 0.315 ” for a size 10 (0.781 ” ID) ring.

The composition of the tungsten-carbide alloy influences a ring’s structural durability and long-term appearance. One that is too hard will be fracture-prone, but an alloy that is too soft may scratch. The hardness is determined by the percentage of binder in the alloy. The rings produced by Tungsten Pride have a 10 percent nickel binder. A higher percentage of binder reduces hardness but adds toughness. “We found that 10 percent nickel provides enough hardness so that the rings are basically impossible to scratch; you can call it a permanently polished ring,” he said. “I sell these to people in wheelchairs, weightlifters, masons, and they just last a lifetime.”

Competitors have made tungsten-carbide rings with cobalt binders, Brosius added, but salts in the skin can leach out the cobalt and cause pitting. “Nickel is more chemically inert than cobalt,” he said.

To machine the rings, the turning center is fitted with both turning and rotating synthetic-diamond brazed tooling. Cycle times average 45 seconds for OD and ID machining and 25 seconds to cut the ring off the tube.

Courtesy of Tungsten Pride

Tungsten Pride machines tungsten-carbide tubing on a CNC turning center for custom wedding, engagement and personal rings.