Power Surge: Inspection Efficiency

Manufacturing parts for the nuclear energy industry, which is growing globally, is expected to expand in the U.S. as well. Three shops explain their strategies.

Nuclear reactor video

Click here for a brief video overview of the Westinghouse AP1000 nuclear reactor, for which some shops are machining parts.

The recent recession cooled demand for electricity but a reviving economy will spark an increasing rate of consumption. The U.S. Department of Energy projects that U.S. electricity demand will rise 24 percent by 2035, about 1 percent each year. That means the U.S. will need hundreds of new power plants, according to the Nuclear Energy Institute. Maintaining nuclear energy’s current 20 percent share of generation from 104 operating reactors would require building at least one reactor every year starting in 2016, or 20 to 25 new units, based on DOE forecasts.

Although only one new nuclear reactor—the Watts Bar Unit 2 in Tennessee—is under construction in the U.S., the NEI reports 65 more are under construction around the world, including 27 in China. In addition, the U.S. Nuclear Regulatory Commission is reviewing 13 combined license applications from 12 companies and consortia for 22 nuclear power plants, according to the NEI.

The Obama administration is also supporting nuclear power to meet pollution-reduction and energy-security goals, with more than $8 billion in federal loan guarantees for Southern Nuclear Operating Co. Inc. to build two Westinghouse latest-generation AP1000 pressurized-water nuclear reactors at its Vogtle plant in Burke County, Ga.

Machining Required

Whether they’re for new nuclear power plants in the U.S. or abroad or for maintaining existing ones, machined metal parts are needed. L&S Machine Co. LLC, Latrobe, Pa., is one job shop that generates about three-quarters of its business machining parts for the expanding nuclear energy industry, noted Bill Kemerer, general manager for L&S. “It did spike my business pretty good,” he said.

Kemerer added that the nuclear parts L&S produces are made of either 300 series stainless steel or 700 series Inconel. Quantities vary from prototype and other low-volume runs to up to 50,000 a year for one part.

Courtesy of Bill Kennedy

L&S Machine mounted a box-like stainless steel part on a Haas TR-160 trunnion and machined four sides of it, performed internal work, then turned it on an angle and rotated each corner to a different angle to perform another operation. One setup replaced four in performing four operations, and machining the part in one fixturing enables the shop to hold 0.002 ” to 0.003 ” true position between fixtures.

L&S produces the parts on 3-, 4- and 5-axis Haas machines, which are dedicated pieces of equipment for nuclear applications because the nickel-base alloy parts cannot be contaminated by contacting materials from other workpieces, such as cast iron, aluminum and copper. “If the customer ran any tests and found any smears on any of that product, then my whole process would be in jeopardy based on not having control of my process,” Kemerer said.

The same holds for metalworking fluids and other equipment L&S uses to process nuclear parts, such as glass bead blasting equipment. “I can’t run anything with any kind of chlorides unless I totally dump and purge all the coolant systems,” he said. “Everything I use for nuclear is dedicated.”

When a prototype job turns into a production run, Kemerer noted that he may opt to make changes to a process, such as changing fixturing, to satisfy new tolerances or other customer require- ments. That might also involve switching cutting tools. “I have tool vendors in here daily, saying they’ve got the latest and greatest mousetrap,” he said. “My reply is bring it in and show me. If you can beat what I’m doing productivitywise, then you’ve got to compete pricewise.”

Sizing Up

The nuclear energy parts L&S machines measure about 8½ “×8½ “×5 ” and smaller. In contrast, many nuclear parts are large. That’s the case at Lindquist Machine Corp., a Green Bay, Wis., custom machine builder servicing various markets by producing parts and the framework and major components of machines.

The company looked to secure work in alternative energy when the U.S. economy slowed at the end of 2008, according to Mark Kaiser, Lindquist’s president and COO. “We started doing some wind energy work, and we got into nuclear energy because it is not solely driven by U.S. economic conditions,” he said.

Lindquist received its first nuclear part order in January 2009 and shipped it last summer. “Now we’re heavy into the nuclear work,” Kaiser said, noting that the company supplies large, prime engineering contractors.

Courtesy of B. Kennedy

From right: Bill Kemerer, general manager for L&S Machine, Brenda DeBernardo, operator, and Josh Campbell, shop manager, check the setup of a part on a trunnion in a Haas vertical machining center.

Initially, Lindquist was machining nuclear parts on an older horizontal boring machine, but the company knew it needed an upgraded machine to continue penetrating that market, according to Ernie Remondini, vice president of lean manufacturing. The work called for a faster, more accurate machine, with a minimum X-axis travel of 30 ‘ and Y-axis travel of 10 ‘. “We narrowed the field to three candidates and selected the MAG FT 3500 horizontal boring mill because it exceeded all the criteria,” Remondini said. “It was the only machine of the three made here in the U.S., and we liked the proximity of the MAG plant in Fond du Lac (Wisconsin).”

Lindquist ordered its FT 3500 with 10.2 ‘ of Y-axis travel, 49.1 ‘ of Z-axis travel, a 60-tool magazine and a live, 155mm spindle with contouring head. According to MAG, the machine’s special-geared AC digital drives maintain the high torque and stiffness needed to cut the 400 series stainless steel nuclear parts at Lindquist, and its 787-ipm rapid-traverse rate and rotary table reduced cycle times. In addition, the machine’s traveling-column design allows virtually unlimited X-axis travel for processing large and long workpieces or multiple batch parts, noted Helene Nimmer, global product leader for MAG.

Lindquist uses the horizontal boring mill to produce specialized fabricated bases, frames, weldments and castings more than 30 ‘ long × 14 ‘ tall and weighing more than 15 tons in quantities of one or two. Tolerances are ±0.0008 ” over 100 “. “They’re all very different,” Kaiser said. “It’s a very low-volume business.”

With short runs comes the need for adaptability. “They purchased floor plates to put in front of that machine, so it allows a bit of flexibility with regard to holding the workpiece and doing their machining applications,” Nimmer said.

Critical Components

East Tech Co. is another manufacturer machining parts for the nuclear energy industry. The Chattanooga, Tenn., design and manufacturing company produces nonsafety- and safety-related parts, such as shafts and impellers, to support a new power plant, noted Roger Layne, company president and CEO. East Tech typically machines the parts in runs of one to 10 on its six Mazak CAT 40 vertical machining centers.

The parts are made of various workpiece materials, including 304 stainless, 4140 alloy steel prehardened to 28 to 32 HRC, A-2 tool steel and abrasion-resistant steel plate prehardened to 54 HRC. For holemaking and threading the latter workpiece, East Tech applies a special carbide drill and carbide tap with a custom coating, which it purchased from MSC Industrial Supply. “A standard carbide tap will not tap it,” Layne said. “We spent 4 weeks developing the process.”

Courtesy of MAG

Lindquist Machine uses the MAG FT 3500 horizontal boring mill with a traveling column to machine large, specialized parts for the nuclear energy industry.

Part size ranges from about ¼ ” to 2 ‘ in diameter. “We don’t have an overhead crane,” Layne said, “so we can only handle small to midsize parts up to 6,000 lbs.”

Layne noted that he had experience producing nuclear parts at a company he worked for and previous clients wanted him to perform that work at East Tech. The initial task involved hiring a quality consultant to write a certification program so the company could target nuclear parts. The next task was establishing the process to avoid stiff financial penalties. “If you don’t follow the procedures and something fails in a nuclear power plant, traceability is going to come back to who made it,” he said. “Everything is serially numbered and each part has a special tag with it so it can’t be mixed up with anything else.”