ALBUQUERQUE, N.M. — A computer control system developed in a cooperative project between Sandia National Laboratories and Delphi Saginaw Steering Systems is saving the automobile parts maker time and money by improving a 50-year-old process that hardens steel parts.
The work grew out of a cooperative research and development agreement (CRADA) signed in 1993 between Sandia, a U.S. Department of Energy multiprogram laboratory, and Delphi Saginaw Steering Systems, a division of General Motors. CRADAs are formal technology commercialization agreements that permit DOE laboratories to collaborate with industry on mutually beneficial research.
This CRADA between Sandia and Delphi Saginaw Steering Systems became a part of the Partnership for a New Generation of Vehicles, a cooperative effort of federal government agencies and the three U.S. automobile manufacturers with a goal of improving both national competitiveness and vehicle performance and efficiency. Although the system was developed in cooperation with Delphi Saginaw Steering Systems engineers, Chrysler and Ford are joining with General Motors in future development activities.
The new system is a way to control induction heat treatment, a process whereby steel and cast iron parts are made stronger by heating them with an electromagnetic coil and cooling them with a water spray. Although the process has been used since World War II, there has been no way to continually monitor the parts and gauge their depth and surface hardness.
Historically the quality control process was accomplished by heating the parts in batches and cutting apart samples for inspection. If the samples met the required specifications, the whole batch was accepted. Because there has been no way to monitor every part, some good parts were scrapped while bad parts may have gone undetected.
Working with Delphi Saginaw Steering Systems engineers, a team of Sandia researchers developed a “closed loop” control system that monitors fundamental changes in the properties of the part. Using knowledge gained through computational modeling and materials characterization studies, the researchers developed a neural network controller that controls the depth and quality of the hardened surface as it is being heated. When the system detects the desired part condition, heating is halted and the part is “quenched” with a cooling spray of water.
“The new control system allows the manufacturer to produce parts that are more uniform and reproducible even if there are variations in material, factory environment and handling procedures,” explains Russ Skocypec, Sandia manager of the project.
Skocypec is manager of thermal and fluid engineering in Sandia’s Engineering Sciences Center. Sandia researchers in the Engineering Sciences Center as well as the Materials and Process Sciences; Electronic Subsystems; and Applied Physics, Engineering and Testing centers worked on the project. They include J. Bruce Kelley, Doug Adkins, Phil Kahle, Charlie Robino, Suzanne Stanton, Tony Russo, Gerry Knorovsky, and Jeff Spooner.
A Delphi Saginaw Steering Systems plant in Saginaw, Mich., began using the system in August to produce shafts for front- drive axles in Saturn automobiles.
Dave Hitz, chief process engineer at Delphi Saginaw Steering Systems, says the control system can be retrofitted to existing manufacturing systems at relatively little cost. The system also is energy efficient, providing a 40 percent savings over alternate hardening technologies, and it is environmentally benign, he says.
Although the new system is being used first by the automotive industry, the researchers say it could be used to heat treat any component subject to high wear and loads. Civilian applications could include power tools, construction equipment, and home appliances. Defense applications could include weapon components, aircraft, tanks, and other military vehicles.
“This project is just one of many examples of how the national laboratories are working with American automobile manufacturers and other companies on research that is mutually beneficial to both the government and industry,” says Bill Robinson, who coordinates more than 20 research programs that Sandia has with automotive industry partners.