Thanks to the addition of a portable digitized dimensional inspection system from ROMER and DELCAM, Concepts NREC is transforming the way turbomachinery is designed, prototyped and tested. The leading developer of these key industrial components, Concepts NREC is revitalizing its Woburn, Massachusetts, operations to handle more demanding turbine designs, and more of them, in less time and with higher quality inspection data, and more of it.

The benefits show up throughout the Concepts NREC product-development process, which is the company's core business. More and better inspection data comes with the company's jump into the digital age, and cuts the time and cost of measuring every surface of even the most complex designs. That in turn is the key to verifying that a prototype turbine meets all its critical design parameters.

The new dimensional inspection system is a portable coordinate measuring machine (CMM), consisting of a seven-axis INFINITETM Arm from ROMER, Wixom, Michigan, USA, and PowerINSPECT from DELCAM, Salt Lake City, Utah. ROMER is a unit of Hexagon AB in Nacka Strand, Sweden. DELCAM plc is headquartered in Birmingham, UK.

The portable CMM is a key part of a significant revitalization of operations for this 55-year-old company. The CMM is dedicated to shop floor operations replacing in many cases gauges, Vernier scales, calipers and micrometers. Because turbine wheels demand precision beyond the capability of any portable, the company also uses a Zeiss CMM isolated in a vibration-free room that is temperature- and humidity-controlled.

Purchased in June 2006, the portable CMM immediately paid for itself by avoiding production errors that would have led to scrapping a pair of integrally cast and machined turbine "wheels" worth $30,000 apiece. On its second job, the portable cut two weeks out of the usual ten-week development cycle, allowing Concepts NREC to better meet the delivery schedule for a customer hard-pressed for time.

"Inspections with the portable are very quick, very accurate and very cost effective," said Jeff Pfeiffer, Director of Business Development - Products and Services at Woburn. "But the really big gain is not having to break setups on machine tools every time we need inspection data."

In a nutshell, the portable CMM has:

• Slashed inspection time to hours from weeks
• Slashed inspection setup time to minutes from hours
• Generated far more data with three to five times greater accuracy
• Vastly increased the variety of in-process measurements
• Built much greater confidence in the data since complete machining setups and fixtures and can now be measured.

Overall benefits to the company include a significant boost to its core turbine wheel business-design, development, simulation and physical testing-with fully digital in-process inspection data. Concepts NREC has a never-ending need for dimensional data to feed these activities.

Turbomachinery is found throughout power generation, gas separation, axial and centrifugal pumps and compressors, fuel cells, turbochargers, and on-board power systems for airliners. Turbine wheels are used as compressor stages, impellers, rotors, stators, inducers, diffusers, propellers and even seals. Worldwide, dozens of companies produce them and most rely on Concepts NREC for new designs. These "wheels" are disks or hubs with four to 30 airfoil blades around their perimeters. They are machined from bar stock or forged metal disks. So that the wheel balances perfectly, every blade must be identical and those blades have complicated, twisting three-dimensional shapes. In cross-section, the individual blade looks like an extended, curved teardrop, hence the need for five-axis machining and inspection.

RESULTS: Weeks to Hours, Hours to Minutes

While Concepts NREC's previous manual inspection methods generated good numbers, the new fully digital methods very quickly gather several times more numbers, and they do so with far less disruption of machining operations. The blades of turbine wheels require dozens of different exacting and exhaustive inspections with the ROMER and PowerINSPECT:

• "Streamline" measurements, which are lines of 120 closely spaced, touch-probed points to
• Profiles across blade leading edges
• Blade thicknesses in various sections and trailing edges
• Blade curvatures, cross-sections and twists on both sides
• Relative locations of blades to each other and to their hubs.

"A complete blade measurement requires nearly a thousand touch-probed points," said Marty Heald, shop manager at the Product Center. "Today, all this takes about four hours. For most of these measurements previously, we had to take single sets of data, make single measurements on our CMM, and manually plot them against the model in a CAD package. It took a complete workday just to gather the data and many more hours to manually plot and inspect the points against the model. Now with the ROMER Arm and PowerINSPECT, the complete process takes about four hours."

Overall, inspection times average three to five times faster with the portable CMM and those gains go right to delivery time.

"Deliveries are critical for us when we have a customer who needs turbine-compressor replacement parts fast," Pfeiffer said. During a scheduled outage for planned maintenance, or a breakdown, every day of lost production costs tens of thousands of dollars. At large refinery and petrochemical plants, a day of lost production can cost a million dollars or more.

Concepts NREC is the world's leading independent, full-service turbomachinery design and development organization. It provides manufacturers, users, government agencies, and the engineering community with technology tools, services, and products that have helped develop some of the world's most advanced products.

Concepts NREC works with titanium, InconelTM 918 and other Inconel alloys, aluminum forgings, alloy and stainless steels, nickel and bronze. The company also works with wax patterns for investment castings and unfired (or "green") ceramics.