Kia recently recalled over 9,000 Sorrento SUVs and Hyundai recently recalled over 20,000 Santa Fe Sport vehicles due to potential fracture in the front axle. The NHTSA announced that “due to a manufacturing issue, the right front axle shaft may fracture.” The fracture could result in a loss of power to the wheels or cause the vehicle to roll when parked.
It is possible that this manufacturing issue and the resulting axle failure was due to the improper heat treating of the axle shaft. Then, during the normal stresses of in-service use, the front axle cracked.
Testing an axle shaft for proper heat treatment and hardened case pattern location is a relatively simple test that can be done with eddy current right on the production line. Integration of the eddy current test into the production line allows manufacturers to test 100% of the axles without adding additional process time or separate processing steps. This not only reduces scrap costs, but can greatly reduce warranty costs. Eddy current can also be used to test for cracks in axles and other components.
If we were to assume that each recall cost $250 (a pretty conservative estimate), warranty costs would have exceeded $7.25M – not including bad press and customer dissatisfaction. This makes the cost for an eddy current system pretty insignificant.
While fasteners may not be expensive end items, failure in critical applications can cause catastrophic effects. Criterion NDT provides in-line heat treat and crack non-destructive testing systems to verify the integrity of all part coming off an assembly line.
In its 2000 annual survey, Quality Magazine found that only 43.9% of manufacturers were performing “in-process” inspection of parts. Today, the same survey indicates 95% are doing so. Criterion NDT’s eddy current testing systems are designed to seamlessly integrate into modern manufacturing processes and support in-process inspection.
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.
During the past couple of years we have all witnessed many changes. Factories have closed and people have either lost jobs or been shuffled around within their existing organizations. Those who were fortunate enough to retain employment may have found themselves in new positions and may also have aquired added responsibily for departments, personnel and equipment. Criterion NDTis here to help support those companies and the individuals who use the Zetec or Uson Eddy Current “Component Testing” Instrumentation. If you need assistance with your component testing application, or just have an interest in a quick “refresher” on the operation of the test instrumentation, please give us a call at 1-253-929-8800.
Article titled “Eddy Current Validates Critical Heat Treat Processes” published in the June 2011 issued of Quality Magazine. The article covers the utilization and benefits of eddy current testing for automated in-line evaluation of heat treated products. http://digital.bnpmedia.com/publication/?i=71537&p=70
Criterion NDT will present a paper on Advancements in Eddy Current Heat Treat Testing at the 2011 Quality Conference. The Conference takes place from April 11th – 13th in Charlotte, NC. For more information on the the Conference, visit http://www.qualitymagconference.com.
GM expanded an earlier recall of some 2011 model-year trucks and SUV’s due to a heat treatment process failure of a rear axle cross pin.
This is another prime example of why proper heat treatment process verification/material structure testing of critical components with eddy current is so important.
It’s likely that a rear axle cross pin is a relatively inexpensive part to produce, but the cost of failure can be many times greater. Properly installed and operated eddy current test systems can help to reduce and/or eliminate the risk of experiencing this type of product failure.
Don’t wait until it’s too late to add eddy current testing to your manufacturing quality process. Like insurance, you’ll be very glad you had it when you needed it.