Bearings are subject to rising demands in our high-tech world. Especially the inner and outer rings work under severe loading demands. They can withstand the stresses long-term in case the heat treatment process is successful, and they have their specified hardness and case pattern. Heat treatment is a complex process with many parameters responsible for the perfect product, so rings must be tested for a wide defect spectrum. They can be too soft or too hard, annealing or quenching can be faulty or did not happen, decarburization may occur or some rings in the furnace lie on top of each other so that they are only partially hardened. Quite apart from the “worst case” when a not-hardened “green” ring slips among good parts.
What could be more appropriate for product quality than to test 100% of the rings non-destructive after heat treatment for correct microstructure? The established industry standard for this is the eddy current test method. The permeability curves of the test parts are compared with the permeability curves of the reference parts (OK parts). Any deviation shows a different microstructure, and the part is sorted as not good.
Such a complex problem naturally shows differences at different locations of the permeability curve. Thus, a multi-frequency test is highly recommended for the eddy current structure test in order to be able to detect all deviations. ibg's well-known Preventive Multi-Frequency Technology PMFT and its latest fully digital development step (fast test times, enhanced frequency range, and harmonic analysis) is your first choice.
Until the introduction of the fully digital Preventive Multi-Frequency Technology PMFT the test time was so long that relatively large test parts like bearing rings could only reasonably be tested statically, so that all eight test frequencies took part in the test result. As the popular bearing ring types are produced in large numbers a 100% test requires a rather immense test and thus cost and effort. Often it was therefore omitted. The introduction of the fully digital Preventive Multi-Frequency Technology PMFT was the beginning of a new era. Due to its significant reduction of test time a dynamic test of bearing rings is now feasible without concessions regarding test reliability. We have used this technology for the development of our ibg high speed ring sorter, an automatic test device with a speed of maximum of 90 parts/minute and a wide part range (outer diameter 30-120mm, width 9-35mm). Thus, the ibg ring sorting opens up absolutely new opportunities for you on the way to a quick and cost-saving production-accompanying 100% test of a large spectrum of your product range!
The ring rolls down the inlet rail (adjustable to ring width) to the diameter-specific escapement and transport wheel. This height-adjustable star wheel is driven by a gear motor and cycled. It moves the individual rings with constant speed through the rectangular encircling test coil.
The part is detected by a light barrier in the middle of the test coil. This triggers the test in a way that all eight test frequencies can target the test part and are evaluated. The relating 3rd and 5th harmonics are also evaluated at the same time by the ibg eddy current test instrument. The exact setting of the trigger point is important and considerably eased by a graphical display of the test part in the test instrument. In case the test result is OK the flap to the NG discharge closes and the OK part rolls to the next process step on a rail adjustable to ring width. This active OK parts sorting is perfected by monitoring the sorting gate. As an open sorting gate with its resting state always NG, parts are always sorted by the NG discharge to the bad parts container without any further action (failsafe).
The complete test unit is mounted inclined, thus the rings move by gravity through the inlet and outlet rail.
The ring sorting is designed for integration in a production line or to be upgraded with a feeder device on Its inlet. Gapless part feeding is recommended to achieve the maximum test speed. It is also possible to use it to test individual parts and feed the rings by hand.
- test mechanic (with the feeding of parts, the escapement and transport wheel, NG parts chute with sorting gate, cabling, and switch box with control
- bg eddy current test instrument eddyliner or eddyvisor S and a pair of rectangular test coils (test & compensation)