Investigation of Conveyor Pulley Shaft Failures
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TECHNICAL ARTICLE—PEER-REVIEWED
Investigation of Conveyor Pulley Shaft Failures D. Satish Kumar • Pradeep Agarwal V. Jagdeesh • Madhu Ranjan
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Submitted: 22 March 2011 / in revised form: 15 July 2011 / Published online: 1 September 2011 Ó ASM International 2011
Abstract The cause for failures of shafts in a conveyor pulley in iron-making unit at JSW Steel has been investigated. Visual, metallographic, chemical, and fractographic studies were carried out in this study. Fracture studies of the shaft revealed shear failure because of overload. Detailed investigation revealed that the source of overload and cause of failure to be the end disk of the pulley drum, which is not considered a critical component. The disk material complies with the required material specification but failed because of changes in metallurgical characteristics during welding. Severe centerline segregation in the end disk drastically reduced its strength and service life, leading to premature failures. It was found that end disk welding failures led to overloaded bending stresses, thereby causing an imbalance in the shaft rotation and leading to failure.
therefore becomes important to conduct detailed investigations of any failure in a conveyor system to avoid repetition of the failure process. The conveyor pulley assembly is an integral structure that relies on the pulley and shaft working and functioning together. A conveyor system consists of a belt and two or more pulleys, with a continuous loop of material that rotates about them. The pulleys are powered to move the belt and the material on it. JSW Steel is a 7-mtpa integrated steel plant (one of the largest in India) and utilizes a series of conveying systems for its material transfer. The most common defect in such system is the pulley shaft failure which may arise from several reasons. The present investigation concerned repeated shaft failures in the raw material-conveying system of the iron-making units.
Keywords Shaft failure End disk Centerline segregation
Visual Inspection
Introduction Conveyor belts have many applications in today’s manufacturing industries. Bulk material handling, distribution, and other material transportation needs are carried out using conveyor belts. Hence, conveying systems become one of the most critical components for continuous and trouble-free operation in many industries. Any stoppage in conveyor operation may result in loss of production. It D. S. Kumar (&) P. Agarwal V. Jagdeesh M. Ranjan JSW Steel Ltd—R&D and SS, Toranagallu Dist, Bellary 583275, Karnataka, India e-mail: [email protected]
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Shaft failures at raw material conveyor pulley at the ironmaking unit (Fig. 1) were reported and then investigated in this failure analysis. It was observed that frequency of failures had increased in recent past and, partially because of this increase, a detailed investigation of the failures was made. The reported pulleys are of drum type (Fig. 2) with the central shaft supported by end disks. Shaft has been found broken inside the d
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