The Plunger return spring of Starter Solenoid is prematurely failed during service. The said failure is presumed to be associated with the combined effects of wear, cold drawn micro crack and tool mark formed during the service. In-order to understand the cause of the failure, the present paper aims to investigate the spring failure at 203k cycle, by Chemical analysis, Scanning Electron Microscope and Vickers hardness assessment. The test reports from the above said assessments disclose surface irregularities and does not show any noticeable change in chemical composition and hardness. The studies reveal that, the wear scratches are formed due to non-uniform contact of plunger components, which cause the surface crack in the internal dia of the spring. Further, Oxide inclusions act as crack initiation sites, where Crack initiation and propagation route are clearly observed in the Scanning Electron Microscope images. This paper, further discusses the methods to improve the spring life.
展开▼
