Ford Motor Company announced this week that it is recalling over 200,000 Freestar and Mercury Monterey minivans made during the 2004 and 2005 model years, because their torque converter output shafts may fail. A number of the failures were found to be attributed to the torque converter output shaft splines stripping, causing a sudden loss of power to the drivetrain. As of this writing, the actual reason for this spline failure is not known. However, it is not outside the realm of possibility that this failure may ultimately be attributed to an improper heat treatment of the output shaft splines, which was not identified during the manufacturing process.
Eddy current test systems are one of the best ways to monitor the quality of heat treatment processes at production line speeds. A properly configured eddy current system can automatically sort out suspect bad product and alert production personnel to a potential upstream process failure. Early identification by eddy current testing can help to minimize quarantined product, reduce scrap and save money. Most importantly, the use of eddy current testing for material heat treatment (material structure) verification ultimately reduces the odds of experiencing the embarrassment of shipping product that does not meet a customers quality standards, or worse, fail during its intended use.