The unique requirements of an electroplatable superabrasive CBNgrit used in profile grinding of hardened steel gears as well asthe attributes and grinding behavior of a new CBN developedspecifically for this application are discussed. Profile geargrinding parameters were simulated in through-hardened AISI 4140steel (56 HRC) and the grinding performance of the newCBNwascompared against a competitiveCBNgrade widely used in theapplication. Consistent with field criteria, grinding performancewas characterized based on occurrence of ‘burn’ or ‘form’ failure.The ‘burn’ or metallurgical phase transformation failure wasdetected by Barkhausen Noise Analysis (BNA) and corroborated bymicrostructural and microhardness evaluations. The ‘form’ failurewas simulated by tracking average radial wheel wear to a thresholdvalue where form loss was expected to occur. Grinding testsindicate that the new CBN grit can grind 35% more parts compared tothe competitive CBN grade before burn failure. In addition, the newCBN displayed a lower wear rate. The new CBN grade also exhibited aunique ability to grind with lower grinding power, resulting in anear constant BNA response on the ground surface throughout thetest. This impliedminimal microstructural change on the ground partfrom start to end of the test compared to the progressive softeningof ground surface noticed with the competitive CBN.
- Edition:
- 12
- Published:
- 10/01/2012
- Number of Pages:
- 13
- File Size:
- 1 file , 590 KB
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