Cause Analysis on Grinding Cracks of a Gear

Cracks were produced on the surface of a gear after girnding. The cracks of the gear tooth top were normal grinding cracks, while the cracks of the gear tooth root were unconventional grinding cracks with larger depth. The causes of the cracks were analyzed by means of chemical composition analysis, non-metallic inclusion detection, metallographic examination and so on. And the grinding cracks were classified from the stress point of view. The results show that the friction stress increased sharply by large amount of feed when the gear was grinding, and the surface of the material was cracked under the combined action of the friction stress and thermal stress, resulting in the cracks of the gear tooth top and tooth root produced. The grinding cracks were classified from the angle of dominant stress caused by induced grinding cracks, and the grinding cracks were divided into the grinding cracks dominated by internal stress and the grinding cracks dominated by friction stress. The cracks of the gear tooth top belonged to the grinding cracks dominated by internal stress, and the cracks of the tooth root belonged to the grinding cracks dominated by friction stress.