FAILURE ANALYSIS AND MODIFICATIONS OF CARBURIZED GEARS
Raafat Ibrahim Mohamed Goher;
Abstract
Summary:
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’ 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. For this reason, the study aims to find a high strength material which can help in overcome more stresses than the above-mentioned material and it was found that the material DIN 1.5860 (14 Ni Cr 18) could do this. But since this material is coded as aerospace material and it has a shortage of, data and researches so, this material is subjected to a variety of heat treatment conditions for discovering the best conditions which verifying high strength, toughness and wear resistance. Sets of specimens were manufactured, heat treated under variable conditions and mechanically tested. For material 18CrNiMo7-6 the relation between, carburizing time and case depth was correlated. For material 14NiCr18, it could obtain high tensile and impact strengths at a certain carburizing and tempering conditions for both oil and water quenching media. Also, wear resistance was tested where good results are obtained.
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’ 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. For this reason, the study aims to find a high strength material which can help in overcome more stresses than the above-mentioned material and it was found that the material DIN 1.5860 (14 Ni Cr 18) could do this. But since this material is coded as aerospace material and it has a shortage of, data and researches so, this material is subjected to a variety of heat treatment conditions for discovering the best conditions which verifying high strength, toughness and wear resistance. Sets of specimens were manufactured, heat treated under variable conditions and mechanically tested. For material 18CrNiMo7-6 the relation between, carburizing time and case depth was correlated. For material 14NiCr18, it could obtain high tensile and impact strengths at a certain carburizing and tempering conditions for both oil and water quenching media. Also, wear resistance was tested where good results are obtained.
Other data
| Title | FAILURE ANALYSIS AND MODIFICATIONS OF CARBURIZED GEARS | Authors | Raafat Ibrahim Mohamed Goher | Issue Date | 2018 |
Recommend this item
Similar Items from Core Recommender Database
Items in Ain Shams Scholar are protected by copyright, with all rights reserved, unless otherwise indicated.