Failure analysis of six-cylinder passenger car engine camshaft

Document Type : Original Article

Authors
Karim Aliakbari 1
Jafar Langari 2
1 Department of Mechanical Engineering, Technical and Vocational University (TVU), Tehran, Iran.
2 Department of Mechanical Engineering, Faculty of Engineering, University of Bojnord, Bojnord, Iran
10.22034/stme.2022.162708
Abstract
 The camshafts are responsible for controlling the timing of the intake and exhaust valves at the right time in internal combustion engines. In this study, failure analysis was performed on two camshafts in a six-cylinder car made of gray cast iron. One camshaft failure occurred after about 177,000 kilometers and the other after about 208,000 kilometers between cam 1 and 2. In order to investigate the cause of cam failure, first, a series of tests including determination of chemical composition, microstructure, hardness measurement, and fractography were performed. The morphology of the fracture surface showed that the growth of the intergranular crack was from the zone of stress concentration and accompanied by ratchet marks. The hardness measurement results of the camshaft cross-section measured a maximum of 155 HB, while the average surface hardness values of the heat-treated surfaces are suggested to be at least 480 HB. The results of the investigation showed that the phenomenon of crack initiation and eventual failure of the cam can be caused by factors such as excessive load, low hardness, and the presence of impurities in the stress concentration zone of the camshaft.
Keywords
Automotive engineering
Camshaft fracture
Microstructure
Fractography
Failure cause
Subjects
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Science and Technology in Mechanical Engineering
Volume 1, Issue 1 - Serial Number 1
February 2023
Pages 70-82

  • Receive Date 26 August 2022
  • Revise Date 08 October 2022
  • Accept Date 11 December 2022
  • First Publish Date 11 December 2022
  • Publish Date 20 February 2023