Failure Analysis of a Gearbox of a Conveyor Belt
- PDF / 1,594,821 Bytes
- 7 Pages / 595.276 x 790.866 pts Page_size
- 10 Downloads / 282 Views
TECHNICAL ARTICLE—PEER-REVIEWED
Failure Analysis of a Gearbox of a Conveyor Belt Kaushal Kishore
. Ankush Sharma . Goutam Mukhopadhyay
Submitted: 27 June 2020 ASM International 2020
Abstract Gearbox of a conveyor belt at a sinter plant failed prematurely during service. It led to an interruption in the supply of raw materials for sinter making and therefore affected the productivity. Detailed analysis of the failure of the gearbox was carried out. Observation reveals material chip off from teeth portion with multiple beach marks and striations confirming fatigue mode of failure. However, no gross metallurgical abnormality was observed as the material was supplied in quenched and tempered condition with a suitable case depth in teeth without any discernible nonmetallic inclusions. This directed the investigation toward maintenance-related issues, and it came out that the viscosity of the lubricant in use was significantly lower. Also, investigation of earlier ferrography suggested that the lubricant contained dark metal oxides and wear debris which may lead to inefficient lubrication. Therefore, it was concluded that gear failed in fatigue mode due to lubrication related issues. Keywords Gearbox Fatigue Beach marks Striation Lubricant viscosity Case-carburized steel
K. Kishore (&) G. Mukhopadhyay Scientific Services, Tata Steel, Jamshedpur 831001, India e-mail: [email protected]; [email protected] A. Sharma Shared Services Technology Group, Tata Steel, Jamshedpur 831001, India
Introduction Gearboxes are the power transmission systems used to reduce the speed and increase the available torque at its output shaft. These are integral components of most of the engineering systems. Even in this era of rigorous condition monitoring, gearboxes fail before planned replacement schedule [1]. This leads to unexpected downtime and decrease in productivity. Analysis of failed gearboxes is essential to find the root cause(s) of the failure and to take preventive actions. In this paper, failure analysis of a gearbox used to drive a conveyor belt at a raw material handling division of a sinter plant is presented. The conveyor belt transfers raw materials like coke, pellet and sinter to blast furnace area where they are used to produce liquid iron. This conveyor belt is driven by a gearbox that consists of a set of four gears placed in series. Gearbox capacity was 850 kW, rated speed of 1500 rpm with service factor 2.13 and motor power 400 kW. The reduction ratio was 35:1 and input and output torques to be 5411.27 and 189,394.45 N-m, respectively. It was a three-stage gearbox, having input shaft, 1st intermediate shaft, 2nd intermediate shaft and an output shaft. Gearbox failed after 5 years of service life, although its expected life was at least 12 years. This gearbox operated continuously throughout the day, except in case of planned maintenance shutdowns, usually once in a year for a couple of days. The failure led to an operational delay of around seven hours and had significant economi
Data Loading...
