Failure Analysis Of Gear Material

Abstract

Presently, there is great challenge in front of automotive industries to overcome failures existing in gears. In order to study failure analysis of gears in industries, the present work was planned. Gears have wide variety of applications. They form the most important component in a power transmission system. Their applications vary from watches to very large mechanical units like the lifting devices and automotives. Gears generally fail when the working stress exceeds the maximum permissible stress. Advances in engineering technology in recent years have brought demands for gear teeth, which can operate at ever increasing load capacities and speeds. The gears generally fail when tooth stress exceeds the safe limit. Therefore, it is essential to determine the maximum stress that a gear tooth is subjected under a specified loading. Analysis of gears is carried out so that these can be prevented from failure. In this study the technology of gears is presented along with the various types of failures that gears have. The causes of these failures are studied. The type of stress related failure due to (fatigue failure) of a gear tooth because of stress concentration is detailed in this thesis. Before testing the mechanical properties, it is essential to understand their structural features as structure is going to govern the properties. Considering this aspect the proposal was planned. Detailed metallurgical analysis was conducted on the fractured gears and compared with the unfailed gears in service. Results showed that gears hardness values were higher than values stated in the literature. The thesis describes about the different types of gears used in industry, their properties and limitations. In order to overcome these limitations, some ideas were planned and accordingly experiments were designed and performed. In this work different types of failures existing in gears have also been discussed. With the help of microstructures obtained from optical microscope and SEM, it was convenient to study the defects existing in failed gear and methods, to reduce the failure, has been suggested.