Conference Papers
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Item Prediction and Assessment of LHD Machine Breakdowns Using Failure Mode Effect Analysis (FMEA)(Springer Science and Business Media Deutschland GmbH, 2020) Balaraju, J.; Govinda Raj, M.; Murthy, C.S.N.Across the world, production industries are always searching for enhancement of productivity by producing the targeted level of production. In the mining industry, Load Haul Dumper (LHD) is one of the major production equipments generally utilized as an intermediate level technology-based transportation system. LHDs are prone to uneven modes of multiple failures/breakdowns due to harsh operating environmental conditions. This leads to a decrease in the performance of the equipment and increases the maintenance cost, the number of unplanned outages (downtime), as well as loss of production levels. This can be controlled by adequate prediction of machine failures through root cause analysis (RCA). In the present investigation, a well-known fault prediction technique, i.e., failure mode effect analysis (FMEA) was utilized to identify the modes of potential failure, causative factors and recognize the effects of these failures on performance and safety. The risk-based numerical assessment was made by prioritizing the failure modes through the risk priority number (RPN) model. The criticality of failure was estimated using RPN values. They are calculated by the product of risk indexed/ruled parameters [severity (S), occurrence (O) and detection (D)]. Further, an attempt has been made to suggest suitable remedial actions to reduce or eliminate the various potential failures. © 2020, Springer Nature Singapore Pte Ltd.Item Shortcomings of Vibrating Screen and Corrective Measures: A Review(Springer Nature, 2020) Shanmugam, B.K.; Vardhan, H.; Govinda Raj, M.; Kaza, M.; Sah, R.; Harish, H.Screening is a process of separating two or more materials of size ranging from fine to coarse of different shapes, particle sizes and densities. The conventional vibrating screen is widely used in mineral and mining industries for performing sizing operation. This paper will be on the review of the various shortcomings of the conventional vibrating screen. The review was carried out through literature survey and plant visit. The paper also involves the remedial measures to be taken to overcome the shortcomings of the conventional vibrating screen. Some of the corrective measures are reduction in number of components also reduces overall screen load, angular velocities, stress, wear or damages to the screen, screen replacement, downtime and overall cost of production. The circular vibrating motion provided to the screen will give larger amplitude and stroke length of the screen which increases screening efficiency. The overall outcome of remedial action will lead to improved screening efficiency. This paper also provides the idea for the optimization of the vibrating screen design which can reduce the power consumption, friction and also provide high screening output. © 2020, Springer Nature Switzerland AG.Item Reliability Analysis of LHD Machine - A Case Study(Springer Nature, 2020) BalaRaju, J.; Govinda Raj, M.; Murthy, C.S.N.In the present global scenario, survival of the industry is more critical unless it produces their intended targets. Accomplishment of expected rate of production levels are depends on the performance of equipment. Hence, it is very important to predict the maintenance schedules for replacement or repair actions of the defective parts. Keeping in view, every industry is constantly looking for enhancement equipment life. Reliability analysis is one of the well appropriated techniques used to estimate the life of the equipment. In this paper, performance of Load-Haul-Dumper (LHD) has been analyzed. Renewal process approach has been utilized for reliability investigation. Best fit distribution of data sets were made by the utilization of Kolmogorov-Smirnov (K-S) test. Parametric estimation of theoretical probability distributions was done by utilizing Maximum Likelihood Estimate (MLE) method. Reliability of each individual sub-system has been computed according to the best fit distribution. In addition to that, reliability based preventive maintenance (PM) time schedules were calculated for the expected 90% reliability level. The possible recommendations were suggested for improvement of reliability level. © 2020, Springer Nature Switzerland AG.Item Investigations of hand transmitted vibrations and associated health risks in load haul dumper operators based on different components of a work cycle(Elsevier Ltd, 2023) Sridhar, S.; Govinda Raj, M.; Mangalpady, M.Load Haul Dumpers (LHDs) are operated in underground mines to transport ore/waste rock under extreme conditions. The operating conditions of the LHDs make the operators susceptible to occupational vibration exposure, including Hand Transmitted Vibrations (HTVs). To date, no research literature is available concerning the evaluation of HTVs based on different components of the LHD work cycle. In the present research study, HTV data were collected by mounting a hand strap on tri-axial accelerometer to the operator's hand in contact with the steering device of the LHDs. Frequency-weighted root mean square (WRMs) acceleration values for all the three measurement axes were collected during different components of the LHD work cycle, namely mucking, loaded travel, unloading, and empty travel. High vibration responses were recorded during the mucking operations, followed by empty hauling. Out of the eight LHDs considered for the study, three LHDs had total daily vibration values A(8) more than that of the stipulated Exposure Action Values (EAV) of 2.5 m/s2, the highest recorded being 2.9 m/s2 in the LHD designated L-6. Health risk assessment was carried out based on EU Directive 2002 and ISO 5349:2001, which showed that operators of three LHDs were at risk of developing health issues such as finger blanching within 12 years of their work life. Strategies to mitigate HTVs should focus on the component of the work cycle and the dominant axis of vibration along with the total daily vibration magnitudes. Operating the LHDs using remote controls during mucking can significantly reduce the total vibration magnitude within daily exposure limits. © © 2023 Elsevier Ltd. All rights reserved.