Search

Purpose Reconfigurable vibrating screen (RVS) is an innovative beneficiation machine designed at Tshwane University of Technology, Republic of South Africa (RSA); with adjustable screen structure to ensure sorting, sizing and screening of varying mineral particles (sizes and quantities) demanded by the customers in a cost-effective manner through the screen structure geometric transformation. In order to ensure that this machine is optimally maintained and managed when utilized in surface and underground mining industries, there is a need to establish or ascertain the best maintenance practices that would be used in optimally managing the RVS machine using decision making techniques. In view of this, the purpose of this paper is to ascertain the best maintenance practices that would be used to optimally maintain and manage the RVS machine when used in surface and underground mines. Design/methodology/approach Decision making techniques such as weighted decision matrix (WDM) and analytical hierarchy process (AHP) were used in this research work to establish the best maintenance practice for optimally maintaining and managing the RVS machine using relevant literature survey on maintenance management systems as well as the different maintenance criteria decision indices obtained from different conventional vibrating screen machine manufacturers and maintenance experts. Findings Based on the results obtained from the WDM analysis, it was anticipated that e-maintenance (e-M) system embedded with diagnosing and prognosing algorithms; with a cumulative weight score of 2.37 is the best maintenance practice for managing the RVS machine when used in surface mines, while AHP with deeper decision making analysis anticipated that the robotic-driven maintenance (RM) system with an important decision criteria; safety, and a cumulative hierarchy score of 28.6 percent, supported by e-M management system with a cumulative hierarchy score of 17.6 percent are the best maintenance mix that could be used in optimally maintaining and managing the RVS machine, when used in a craggy and hazardous underground mining environment. Practical implications To this effect, it could be anticipated that e-M management system (endowed with the ability to detect fault on the machine, diagnose and prognose the different subsystems of the RVS machine and ascertain the reconfiguration time and process of the RVS machine in recovering production loss during the maintenance of the machine as well as meeting customers demand, etc.) is the best maintenance practice for optimally maintaining the RVS machine when utilized in surface mines while both e-M management system and RM management system (endowed with the ability to carry out automated maintenance tasks achievement under little or no maintenance manager intervention) are also anticipated as the best customized maintenance practices mix that could be used in optimally maintaining the RVS machine, when used in dangerous and hazardous underground mining environment. Originality/value This maintenance management system evaluation and selection for optimal RVS machine functionality will serve as a useful information to different mining machines (and other related machines) maintenance managers, in selecting the best maintenance management system for ensuring optimal functionality, reliability and maintainability of machines used in their industries.

Purpose – The purpose of this paper is to propose a practical method of performing maintenance in the offshore industry where engineers have to manage problems such as the high cost of operations, assuring an high availability of the plant, safety on board and environmental protection. Indeed an efficient maintenance method it is necessary in order to offer methods and criteria to select the rights maintenance strategies keeping in to account the environmental, safety and production constrains. Design/methodology/approach – The paper provides an overview of reliability centered maintenance (RCM) and reliability, availability, maintainability methodologies and an integration of the two methodologies in a particular case study in the oil and gas sector. Findings – This paper suggests an improvement of the well-established RCM methodology applicable to industries with high priority level. It is proposed an integration between a reliability analysis and an availability analysis and an application on the offshore oil and gas industry. Practical implications – The methodology provides an excellent tool that can be utilized in industries, where safety, regulations and the availability of the plant play a fundamental role. Originality/value – The proposed methodology provides a practical method for selecting the best maintenance strategy considering the equipment redundancy and sparing, the asset’s performance over long time scales, and the system uptime, downtime and slowdowns.

Purpose – The purpose of this paper is to propose a method to compute RAMD indices to measure and improve the performance of skim milk powder production system of a dairy plant under real working conditions. Design/methodology/approach – The present work is carried out by developing performance model based on Markov birth-death process. The skim milk powder production system consists of six units. The first order governing differential equations are derived using the mnemonic rule and further solved to calculate RAMD indices i.e. reliability, availability, maintainability, dependability, MTBF, MTTR and dependability ratio for each subsystem of the system. Findings – The subsystem SS1 comprising of chiller and cream separator is the most critical from maintenance point of view, as the reliability, availability, maintainability, dependability, MTBF and dependability ratio indices are low as compared to those of other subsystems of skim milk powder production system of the dairy plant. Originality/value – The RAMD indices of the present work is very useful for finding the critical subsystem and its effect on the performance of the system working under real working conditions. Further, based on findings the maintenance priorities for various subsystems can be decided.

Purpose – The purpose of this paper is to demonstrate a tactical approach to cope with the issues related to low availability of repairable machines or systems because of their poor reliability and maintainability. It not only explores the significance of availability, but also embarks upon a step-by-step procedure to earmark a relevant replenishment plan to check the mean time between failure (MTBF) and the mean time to repair (MTTR) efficiently. Design/methodology/approach – The literature review identifies the extent to which availability depends on reliability and maintainability, and highlights the diversified challenges appearing among repairable systems. Different improvement initiatives have been suggested to avoid downtime, after analyzing the failure and repair time data graphically. Relevant plots and growth curves captured the historical deviations and trends along with the time, which further helps to create more robust action plans to enrich the respective reliability and maintainability of machines. During the case study, the proposed methodology has been tested on four SPMs and successfully validated the claims after achieving around a 98 percent availability at the end. Findings – Graphical analysis is the key to developing suitable action plans to enhance the corresponding reliability and maintainability of a machine or system. By increasing the MTBF, the reliability level can be improved and similarly quick maintenance activities can help to restore the prospect of maintainability. Both of these actions ultimately reduce the downtime or increase the associated availability exponentially. Research limitations/implications – The work revolves around the availability of SPMs. Moreover, SPMs have been divided only into series sub-systems. The testability and supportability aspects have not been considered thoroughly during the fabrication of the approach. Originality/value – The work focusses on the availability of systems and proposed frameworks that helps to reduce downtime or its associated expenditure, which is generally being ignored. As a case study-based work especially on SPMs in the auto sector this paper is quite rare and will motivate affiliated engineers and practitioners to achieve future breakthroughs.

PurposeThe ongoing availability of existing industrial systems/machines depends to a great extent on the form and level of product support. Product support, or the after sale service of a product, is important because it assures the expected function of the product in its operational phase. Product support is affected by a number of factors, including system reliability and maintainability characteristics and the operating environment. The purpose of this paper is to analyze the influence of time independent external factors of industrial systems on product support requirements and spare parts need.Design/methodology/approachThis paper, after discussing the factors influencing product support, describes a method to estimate spare part requirements based on estimation of the actual reliability of a product under the influence of the product‐operating environment using a proportional hazard model. A spare parts estimation software, Spare Management Software (SMS), is used to check the results. Then a case study addresses the management of the spare parts inventory based on the geographical location and required performance of the product.FindingsThe lack of good support and critical spare parts can cause the untimely stoppage of a machine/system. The forecasting of product support and spare parts requirements based on the reliability and maintainability characteristics of systems/components, along with influencing environmental factors, is one of the most effective strategies for preventing unplanned stoppages. The operating environment of a system/machine has a considerable influence on the performance of the system and its technical characteristics, such as its reliability, maintainability, and, consequently, availability. Therefore, the system operating environment should be considered when the required support and spare parts estimation is under review.Research limitations/implicationsIn this research, the focus is on the estimation of the number of spare parts required. Only non‐repairable components/parts in repairable systems are studied. In other words, the paper considers one‐component systems or a single component within a larger system. The operation and maintenance phases are dealt with in the study, along with the external operating environment and time independent influencing factors.Practical implicationsThe introduced method for spare parts estimation will enable management to improve system availability and production line efficiency while minimizing total production costs. Consequently, the plant life cycle cost will be minimized by releasing the tied‐up costs incurred when stocking extra parts for a long time.Originality/valueThe paper provides a new outlook on product support and spare parts forecasting by taking the actual system operating environment into consideration. It helps managers and engineers to be realistic and act pragmatically while running and analyzing technical/industrial systems.

PurposeThe focus of this paper is on reliability and availability design goals. It aims to provide top‐level estimates of the safety and maintainability of future spacecraft systems.Design/methodology/approachThe developed design tool uses basic reliability principles to estimate the probability of a safe mission and the need for repairs/replacement during ground processing, before launch and start of mission, based on the characteristics of the vehicle's main systems: the number of subsystems, the mean time to repair, and the per subsystem average reliability.FindingsA simple reliability, maintainability and safety model is developed to support the top‐level design process of future space transportation vehicles. It also describes how the developed design tool uses various sensitivity analysis functions to improve design decisions.Originality/valueThe goal of the developed tool is to provide engineers/vehicle developers during the early stages of design with a tool that demonstrates the effect on maintainability of improving component reliability and reducing the number of components.

PurposeThe purpose of this paper is to provide an overview of RAMS engineering in industry and research.Design/methodology/approachA range of research articles (1988‐2005) covering RAMS engineering is discussed to provide a practical and theoretical overview of RAMS engineering in industry and research.FindingsThe paper provides information about the current scenario and also about the past scenario of RAMS engineering in research and industry. Research limitations/implications – This paper reviews much of the literature on RAMS engineering. The literature is collected from major journals and conference proceedings, the period covered is from 1988 to 2005. The authors have tried to make it reasonably comprehensive, but those papers which are not included were either inadvertently overlooked or considered peripheral to this survey. In the present work the authors have only considered those articles which have included two or more aspects of RAMS. Practical implications – The paper is a very useful source of information for researchers working in the area of RAMS engineering. Originality/value – This paper offers help to researchers in understanding the current and past status of RAMS.

PurposeThe reliability and maintainability of tunnel infrastructure and systems is an important factor in assuring normal operation of a tunnel. Evaluating availability of a large‐scale tunnel that includes civil, electrical, mechanical and electronic systems is a difficult task. The purpose of this paper is to present a methodology for performing such assessments, featuring the use of the Markov model.Design/methodology/approachThe methodology involves application of failure mode, effect and criticality analysis (FMECA), state space diagram construction, formulation of state space equations, and development of transitional matrices. It also involves transformation of multi‐state models into two‐state models (each comprises of an “up” state and a “down” state) through the use of the frequency and duration method for determining the failure and repair rates, as well as the mean‐time‐between‐failures (MTBF) of the entire tunnel. By using the proposed bottom‐up approach, a MTBF tree linking the availability measures of individual equipment with those of sub‐systems, and ultimately the whole tunnel can be developed.FindingsThe tunnel availability measures obtained by this analysis can be used in making comparisons between different tunnel designs so as to determine the value for money of various options. Furthermore, weaknesses in a tunnel design can be identified in the analysis. The information obtained from this method can also be used to evaluate adequacy, security and maintainability of a tunnel.Practical implicationsThe reliability and maintainability of tunnel infrastructure and systems are crucial factors for ensuring safety of tunnel operation. Unsafe conditions will cause closure of a tunnel. Efforts to improve availability of a tunnel often increase the tunnel's construction cost. Due to the complexity of tunnel systems, it is difficult to compare different tunnel designs, and trade‐off analyses to strike a balance between target availability and construction cost of a tunnel design are seldom performed. This paper presents a systematic methodology to address these issues. This methodology allows tunnel management to evaluate the adequacy, security and maintainability of a tunnel so that design weaknesses can be identified and the value of design improvements can be determined. The methodology can also be used to evaluate designs of other complex systems such as power generation or petrochemical processing plants.Originality/valueA worked example demonstrating the application of the proposed methodology is presented in this paper.

PurposeThis paper aims to examine the strategic value of reliability and maintainability management in achieving competitiveness and customer satisfaction. It looks into performance metrics for organizational performance and associates reliability and maintainability with such metrics.Design/methodology/approachThe design strategy is based on using models for reliability and profitability assessment as well as total quality management models to illustrate how performance metrics for organizational performance can be enhanced.FindingsIt shows there is a need to associate models of profitability assessment to reliability and maintainability management. This will help top management to see the strategic value of reliability and maintainability management and, therefore, adopt necessary organizational transformations to support reliability and maintainability goals.Research limitations/implicationsIt is important that the role of reliability and maintainability as important strategic variables be recognized and considered in future research that evaluates organizational performance and successes.Practical implicationsThe importance of organizational cultural transformation is noted and a transformation of organizational information system to link reliability management to a central information system such as in an enterprise resource planning (ERP) framework is suggested as a process of improving system availability and reliability.Originality/valueThe aim is to have top management perceive reliability and maintainability issues as part of their strategic initiatives. While the value of total quality management in achieving organizational success is well accepted, reliability and maintainability issues are often viewed at the operational level. Yet, they are critical to achieving quality and organizational success.

Maintaining a high level of availability of weapon systems during battles becomes important from the point of view of winning the battle. Due to attrition factors (failure due to battle damage and unreliability) and logistic delays in the repair process, maintaining the required level of availability is difficult. In this paper, we develop a simulation model for availability of fighter aircraft considering multiple failures causing system failure and logistic delays in the repair process. The methodology is based on discrete event simulation using Monte Carlo techniques. The failure time distribution (Weibull) and the repair time distribution (exponential) for the considered subsystems of the aircraft and the logistic delay time distribution (log‐normal) for the logistic factors spares, crew and equipment were chosen with suitable parameters. The results indicate the pronounced decrease in availability (as low as less than 10 per cent in some cases) due to multiple failures and logistic delays. The results are, however, highly sensitive to a combination of reliability, maintainability and logistic delay parameters.

The quality performance of a firm is often assessed by the reliability of the firm’s equipment or machinery. Yet, reliability has not received the same attention as quality. Several organizations today function effectively because the machinery which provides the “system of operation” is highly dependable and reliable. In this paper, we develop a framework that establishes the link between quality, reliability, and maintainability. The aim of this framework is to get corporate attention to focus on reliability issues and also, to establish the link between reliability, company’s bottom line, and corporate survival. A greater focus on “total reliability management (TRM)” will help firms to improve their productivity and efficiency while reducing cost and increasing their competitiveness.

Describes the success story of how Gilman, a division of Giddings & Lewis, Inc., with the help of Blackhawk Technical College, institutionalized reliability and maintainability (R&M) into its quality system and obtained ISO 9001:1994 certification and a declaration of compliance to the QS 9000 Tooling & Equipment Supplement. Looks at aspects such as defining the need for R&M and the integration of effective reliability and maintainability procedures into the quality system. Reports on a comprehensive training effort to educate the organization in R&M.

High reliability, maintainability, safety and supportability are expected from today’s modern systems. In the recent years supportability has been widely accepted as a major factor in logistics discipline. The main purpose of this paper is to demonstrate how advanced mathematical models can be used to analyse the effect of supportability on systems availability. The paper discusses supportability aspects and its effect on operational availability of complex systems using advanced mathematical models like Markov, semi‐Markov and non‐Markov models. The powerful mathematical models discussed in the paper would help reliability engineers and practitioners to predict the logistic support requirements to achieve specified operational availability.

New technologies of coal production have improved machine reliability but increased technical complexity. More man shifts are now devoted to maintenance than to coalface production, so maintainability is crucial. The reorganisation of craft work, to increase labour flexibility and reduce workers′ autonomy, reveals a fundamental conflict between the production objectives of the new systems and human factors. The full productive potential of computerised systems is not being realised because of random breakdowns. The new technology has been designed to circumvent the skills and knowledge of the workforce, but its success depends on harnessing these skills. A system designed to enhance maintenance workers′ skills would avoid these contradictions, raise productivity and improve the working environment.

Aircraft design specifications include stringent quantitative maintainability targets which must be achieved during the design stage of a new aircraft programme. The manufacturer is required to provide servicing guarantees and elapsed time guarantees for the removal/replacement of all mission‐critical, line‐replaceable units. This demonstrates the need for an aircraft‐orientated maintainability prediction methodology, for use in the design process. A suitable methodology is here presented. Initial work checked the servicing requirements and showed initial adequate performance. An elapsed time removal/replacement methodology was evolved which was then computerised to facilitate repeated application during the design process.

The technological level achieved by manufacturing systems in recent years has caused an exponential enlargement of problems to be faced by management, such as cost minimisation, reliability and maintainability allocation, diagnostic system design. A newly developed model for assessing the impact of failures of equipment (subject to multiple repair modes) on system production capability is presented. It is based on the numerical simulation of delay times in the production flow and enables the analyst to consider alternative and realistic policies of failure management, different starting periods and ending procedures of a finite production phase. Some examples of series manufacturing systems, with and without buffer, are analysed and sensitivity analyses are performed to assess the influence of variations of reliability and/or maintainability characteristics of the equipment on the system performances.