Supply of salvaged shafts as new ones: failure cases to study malpractices and their effects
Manoj K Jejurkar,  Dr. Sandip Bhattacharya
Shafts are critical components of many machines, and a damaged shaft can hamper or halt production. When the alternate replacement is not available, in order to restore the production, shafts are repaired mainly either by depositing weld metal or spraying the metal. The weld deposition is a most commonly used methodology owing to its simplicity. Although this methodology is preferred to be only temporary replacement, many instances of misuse were found over the period of time. It has been applied to materials which are only weldable by special procedures, to the indiscriminate building-up of worn out components and for the correction of machining errors. Many failure investigations revealed that the suppliers have been using this technique to supply such repaired shafts to the organizations as a new piece. The recent analyses discussed in this papers includes failure of armature shaft of traction motor of a locomotive and earlier failures of roll shaft of CRM CGL and support roll shafts, etc. are the cases which proved that the shafts were supplied in repaired condition. The weld repair reduces the fatigue strength of the material. As, in most of the materials, tensile strength of the weld is lower than the base metal, these components have lower fatigue endurance. Salvaging of shafts by material deposition using thermal spray technique can be one of the alternatives to have repairs of shaft with better fatigue life but that too is acceptable for temporary repairs. Its misuse during supply of the material is still an issue for inspecting agency of an industry
Keywords- shafts, failure, fatigue, welding, salvaging, deposition, fatigue strength
Cite this Article
Manoj K Jejurkar,  Dr. Sandip Bhattacharya,   "Supply of salvaged shafts as new ones: failure cases to study malpractices and their effects"
, International Journal of Engineering Development and Research (IJEDR), ISSN:2321-9939, Volume.4, Issue 2, pp.2092-2096, July 2016, Available at :http://www.ijedr.org/papers/IJEDR1602367.pdf