Failure analysis and modifications of carburized gears / Raafat Ibrahim Mohamed Goher ; Supervised Mahmoud Mohamed Abdrabou , Badr Shaaban Azzam

Thesis (Ph.D.) - Cairo University - Faculty of Engineering - Department of Mechanical Design and Production

The mechanical failure mainly concentrated in; material selection errors, design errors, production error and heat treatment errors with about 79% of the total failure causes. Gear failure is one of the most important problems facing the gears{u2019} designers, manufacturers and maintenance team. Gear failure may occur due to the errors in design, manufacturing, operating conditions or maintenance. Design errors may also come due to errors in stress analysis, material selection, geometry analysis or heat treatment specifications. Manufacturing errors may be result from the machining accuracy and/or errors, geometrical errors, heat treatment errors, finishing errors or assembly errors. In this work, three industrial gear failure cases were studied and analyzed. It was found that the most failure cases were resulting from the heat treatment specifications, implementation or design analysis. So, the study was aimed to analyzing the failure cases searching for its causes and introducing solutions to the discovered failure causes. The failure studied cases, were made of carburized materials so; the carburization technique of surface hardening was applied. The studied cases material was DIN 1.6587 (17NiCrMo 7-6). The failure reason of the first and second cases were due to errors of; the carburizing depth either less or more than the correct values and decarburization. Those errors were studied and solved. Whereas, the third failure case was due to the high applied stress to the gears

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