Once available only from foreign laboratories, a precision measurement service for manufacturers of automobiles, aircraft, farm equipment, and other large products is now being offered in the United States, thanks to a growing collaboration between the National Institute of Standards and Technology and the Department of Energy's Centers for Manufacturing Technologies at the Oak Ridge Y-12 Plant.
Starting immediately, Y-12 staff in Oak Ridge, Tenn., will calibrate end standards and step gauges up to 1.35 meters long to a certified accuracy of 0.7 micrometer per meter—equivalent to about one-hundredth of the diameter of a human hair. Though varying in appearance and composition, step gauges are akin to long rulers with precisely determined total and incremental lengths. For end standards, only the total length is calibrated.
Manufacturers use these standards as in-house references to verify the accuracy of their own measurement machines, such as those used to inspect the dimensions of finished parts and assemblies of parts. As a quality-assurance check, manufacturers periodically have their reference standards calibrated to ensure measurement accuracy and reliability.
Dennis Swyt, chief of NIST's Precision Engineering Division, says the new domestic service will provide calibrations "at a level of accuracy, cost and delivery equal or superior to that of the best foreign suppliers."
For example, Germany's standards laboratory—the Physikalisch-Technische Bundesanstalt, or PTB—charges U.S. customers about $3,500 (plus overseas shipping charges) to calibrate a 1-meter step gauge to an accuracy of 1 micrometer. Turnaround time is about 90 days, according to Swyt.
For a fee of about $3,000 (plus domestic shipping), Swyt says, the NIST Y-12 service offers a 30-percent improvement in accuracy and a turnaround time of 30 to 45 days.
The service combines NIST's measurement expertise and Y-12's advanced technological capabilities, including a high-precision, large-volume Moore M60 coordinate measuring machine. The mammoth machine is housed in a room in which the temperature can be controlled to within 0.01 degree Celsius.
The accuracy of measurements performed at Y-12 are certified by NIST, the nation's primary measurement and standards laboratory. The measurements are directly linked—or traceable—to national standards. To establish this traceability, NIST measurement experts helped Y-12 staff characterize the facility's CMMs, establish a formal quality system, and implement the statistical process controls that NIST laboratories use to assure measurement accuracy. As a result of these and other steps, measurements performed at Y-12 will be NIST certified.
Initially, the new service will be available for one-dimensional end standards and step gauges up to 1,350 millimeters, as compared with NIST's previous maximum of 750 millimeters. Plans call for extending the upper limit to 1,600 millimeters. As the Y-12 centers' capabilities are characterized more fully, services may be expanded to two- and three-dimensional measurements for calibrating large grid and ball plates.
In partnership with the American Society of Mechanical Engineers, NIST and Y-12 also are proceeding with plans to develop a National Gear Metrology Center, which will provide advanced measurement services critical to the manufacture and quality assurance of precision gears. Housed at the Y-12 Plant, the center recently received a $3 million grant from the Defense Department's Technology Reinvestment Project.
The center and the new measurement service respond directly to U.S. companies' requests for enhanced precision-measurement services to support their manufacturing-improvement and technology-development efforts. For example, a vice president at a major U.S. manufacturing company told NIST that his firm "cannot afford the cost and time of continuing to send reference artifacts to Europe for certification." He termed the lack of a domestic service for calibrating long step gages as "unacceptable."
In December 1992, NIST and the DOE Oak Ridge Centers for Manufacturing Technologies signed an interagency agreement pledging the two organizations to "pursue all avenues of collaboration" that can help to improve the nation's "technological standing."
A non-regulatory agency in the Commerce Department's Technology Administration, NIST promotes economic growth by working with industry to develop and apply technology, measurements and standards.
The Oak Ridge Y-12 Plant is one of three facilities managed by Martin Marietta Energy Systems Inc. for the U.S. Department of Energy. Major technology transfer activities for the Y-12 Plant and Oak Ridge National Laboratory are carried out through the Centers for Manufacturing Technologies.