Showing papers in "Journal of Quality in Maintenance Engineering in 2000"
TL;DR: In this paper, the authors review overall models for maintenance management from the viewpoint of one who believes that improvements can be made by regarding maintenance as a "contributor to profits" rather than "a necessary evil".
Abstract: Reviews overall models for maintenance management from the viewpoint of one who believes that improvements can be made by regarding maintenance as a “contributor to profits” rather than “a necessary evil”. The reasons why maintenance is such a “Cinderella function” are largely historical and can mostly be overcome by new information technology (IT) and its falling cost. Progress is now being held up by outdated notions of what is economically possible in data acquisition and analysis, and failure to revise basic maintenance and reliability concepts, some of which are now 30 years out‐of‐date. Integrated IT permits mathematical optimisation of supra‐departmental management decisions, e.g. co‐planning of production with maintenance, overhaul/renewal of machinery and improvement of product performance/quality. Life‐cycle profit (LCP) is a fair measure of overall effectiveness that emphasises the value rather than the cost of terotechnological activities.
324 citations
TL;DR: In this paper, the authors consider the relationship between total productive maintenance (TPM) and reliability-centered maintenance (RCM) and suggest that RCM is central to the development of such a program.
Abstract: A brief article considering the nature of total productive maintenance (TPM) and reliability‐centered maintenance (RCM) and the relationship between the two. Notes equipment management and empowerment of employees as key features of TPM. Sees the development of an effective preventive maintenance program as essential to effective equipment management and suggests that RCM is central to the development of such a program. Points out that, if implemented within the framework of TPM, RCM can help achieve better results from the TPM implementation.
65 citations
TL;DR: In this paper, the authors argue that there are similarities between both systems and that it is possible and desirable to integrate a safety management system within a QMS to achieve an integrated quality and safety management systems (QSMS).
Abstract: Quality and safety are two important issues in the construction industry. The industry not only looks for good quality buildings but is also keen to promote a safe working environment on construction sites. Quality management systems (QMS) as well as safety management systems (SMS) are already in place in many countries where quality and safety issues are dealt with respectively. Unfortunately, both systems are frequently considered separately. It is the contention of this paper that there are similarities between both systems and that it is technically possible and desirable to integrate a SMS within a QMS to achieve an integrated quality and safety management system (QSMS). The paper highlights the relevant safety elements and quality requirements and, by means of surveys and interviews with quality managers and safety managers, confirms that there are similarities between a SMS and a QMS, making it possible to integrate these two systems, to achieve better co‐ordination and utilisation of scarce resources.
49 citations
TL;DR: In this paper, behavioral aspects of process improvement and maintenance concepts are combined with ongoing commitments to operations management goals, and Causal loop diagramming, part of the system dynamics toolkit, is used to structure the interrelated nature of involved concepts and variables.
Abstract: Drawing from observations made at a couple of manufacturing firms, this paper weaves together behavioral aspects of process improvement and maintenance concepts with ongoing commitments to operations management goals. Causal loop diagramming, part of the system dynamics tool‐kit, is used to structure the interrelated nature of involved concepts and variables. An objective is to offer insights from a systems perspective. The paper offers behavioral explanation for limited success in implementing improvement programs and suggests reversing the traditional “maintenance service supplier‐and‐customer relationship” between maintenance and operations.
47 citations
TL;DR: In this paper, a case on benchmarking for maintenance management in a large-scale power plant is analyzed, where the authors used the benchmarking to search for optimum maintenance management practices in order to improve the overall effectiveness of the operations and maintenance of the plant.
Abstract: The market‐oriented competitive environment in electric utilities has forced many power plants to become more conscious of the role of maintenance management in enhancing their equipment performances and consequently improving the quality of their services. Good equipment maintenance practices can improve the reliability of the power system; maintenance has become the prominent management issue for electric utilities. In recent years, power plants have started using benchmarking to identify the best practices for enhancing their maintenance works. In this paper, a case on benchmarking for maintenance management in a large‐scale power plant is analyzed. Benchmarking is used to search for optimum methods for maintenance management practices in order to improve the overall effectiveness of the operations and maintenance of the plant. By adopting the best practices appropriately, benchmarking could help plants to become more cost‐effective in maintenance. However, for plants looking for breakthrough improvement in maintenance, on top of benchmarking, other means, i.e. intelligent decision support system (IDSS) for maintenance, are required as well.
40 citations
TL;DR: In this paper, a comparative study between two models developed to predict the average hourly maintenance cost of tracked hydraulic excavators operating in the UK opencast mining industry is presented, using the conventional statistical technique multiple regression, and artificial neural networks.
Abstract: Notes that the real test of maintenance stratagem success (or failure in financial terms) can only be resolved when a comparison of machine maintenance costs can be made to some benchmark standard. Presents a comparative study between two models developed to predict the average hourly maintenance cost of tracked hydraulic excavators operating in the UK opencast mining industry. The models use the conventional statistical technique multiple regression, and artificial neural networks. Performance analysis using mean percentage error, mean absolute percentage error and percentage cost accuracy intervals was conducted. Results reveal that both models performed well, having low mean absolute percentage error values (less than 5 percent) indicating that predictor variables were reliable inputs for modelling average hourly maintenance cost. Overall, the neural network model performed slightly better as it was able to predict up to 95 percent of cost observations to within ≤q £5. Moreover, summary statistical analysis of residual values highlighted that predicted values using the neural network model are less subject to variance than the multiple regression model.
39 citations
TL;DR: In this article, an optimization problem to obtain the optimal replacement interval is studied, where the system is minimally repaired at failure and is replaced by a new one at age T. The model assumes that the time horizon associated with the number of replacements is random.
Abstract: An optimization problem to obtain the optimal replacement interval is studied. The system is minimally repaired at failure and is replaced by a new one at age T. The model assumes that the time horizon associated with the number of replacements is random. The total expected cost is calculated, and the optimal replacement interval minimizing the cost is found. A numerical example is used to compare the costs associated with an infinite time line and a random time line, which this model used.
30 citations
TL;DR: In this article, the problem of simultaneously determining the optimal target mean and target variance for a process is considered, which might result in a reduction in variability and in the total cost of the production process.
Abstract: Recently, there has been a lot of interest in the economics of quality control. Many researchers have considered the problem of determining the optimal target mean for a process, but almost all of them have assumed that the process variance is fixed and known in advance. The problem of simultaneously determining the optimal target mean and target variance for a process is considered. This might result in a reduction in variability and in the total cost of the production process. A reduction in variability upholds the modern concept of Taguchi’s loss function, which states that any deviation from the target value incurs economic loss, even when the quality characteristic lies within the specification limits. Taguchi’s loss function is incorporated to extend this study further to jointly determine the optimal target mean and variance.
27 citations
TL;DR: In this paper, the reliability data analysis and modelling of offshore oil platform plant is presented. But, the analysis showed that preventive maintenance is generally effective, but a slight decrease of the periodic inspection intervals is favorable.
Abstract: This paper reports on the reliability data analysis and modelling of offshore oil platform plant. We first analysed the effectiveness of preventive maintenance to the plant concerned, and then identified the key sub‐units and major preventive maintenance activities to be modelled. A modelling technique called the delay time is then used to determine the optimal periodic inspection intervals. The analysis showed that preventive maintenance is generally effective, but a slight decrease of the periodic inspection intervals is favourable.
22 citations
TL;DR: In this article, a continuous-time multi-state Markovian deteriorating system subject to aging and fatal shocks under continuous inspection is investigated, where an action is chosen from {do-nothing, repair, replace} upon each state x transited from the resulting state after the last action and so it is statedependent.
Abstract: A continuous‐time multi‐state Markovian deteriorating system subject to aging and fatal shocks under continuous inspection is investigated in this paper. An action is chosen from {do‐nothing, repair, replace} upon each state x transited from the resulting state after the last action and so it is state‐dependent. Henceforth, a state‐dependent maintenance policy Ri,j(T,N,α) in which two states i < j are used as thresholds to control the repair and replacement in the way that the repair (resp. replacement) is taken whenever the state x satisfies i ≤ x ≤ j – 1 (resp. j ≤ x ≤ L). The performance of this state‐dependent maintenance policy is measured in terms of the expected long run cost rate. An iterative algorithm is provided to optimize the proposed maintenance policy. A numerical example is given to illustrate the method.
22 citations
TL;DR: In this article, a lamp manufacturing company with a lot of highly automated equipment and facilities which depends on modern maintenance strategies as well as MRPII-type production planning and control is described.
Abstract: Very limited research has attempted to consider maintenance strategies in the design of MRPII. The manufacturers who need to optimise the return of their assets and facilities using systematic maintenance management will find that the MRPII system is unable to provide them with the solution. Proper design and integration of maintenance management into MRPII enable the manufacturers not only to manage their production planning and scheduling activities but also to analyse their maintenance history, carry out cost analysis and study the failure trends to determine how the available labour and materials in maintenance can be used effectively. In order to overcome the weakness of the MRPII system in the management of maintenance activities, this paper describes some research work that has been carried out using the integrated definition method (IDEF) model to systematically integrate maintenance into MRPII. Moreover, in order to illustrate the methodology, a lamp manufacturing company with a lot of highly automated equipment and facilities which depends on modern maintenance strategies as well as MRPII‐type production planning and control is described.
TL;DR: In this article, the authors investigated the use of exponential distribution as an approximation for regularly maintained Weibull component and derived the asymptotic relative error, which can be used to adjust the exponential approximation when needed.
Abstract: Exponential distribution is widely used in reliability and maintainability studies although it is well known that the constant failure rate assumption may not be valid. The purpose of this paper is to investigate the use of exponential distribution as an approximation. In fact, for components undergoing regular maintenance or replacement, the exponential assumption can be acceptable. In this paper, the exponential approximation for regularly maintained Weibull component is studied. The approximated exponential distribution using the average failure rate is compared with the exact reliability. The asymptotic relative error is derived, which can be used to adjust the exponential approximation when needed. Based on the framework of exponential approximation for Weibull distributed components, the problems of decision‐making regarding the optimal maintenance time and spare allocation are also addressed.
TL;DR: In this article, the authors investigated the effect of changes in the machine speed and load on the amplitudes of rolling element bearing defect frequencies and highlighted the reasons behind the stoppage times and consequential economic losses incurred by unplanned stoppages.
Abstract: Relevant and reliable data from the surroundings in addition to the vibration measurements are required to achieve effective diagnosis and prognosis when a vibration‐based maintenance (VBM) policy is used. The main conclusion is that the variation in the machine load and speeds influences the amplitudes of rolling element bearing defect frequencies. Therefore, changes in the machine speed and load should be considered when interpreting vibration spectra. This will improve the effectiveness and accuracy of fault diagnosis and prediction of the time to maintenance action. The paper classifies stoppage times and highlights the reasons behind them. Also, it discusses the consequential economic losses incurred by unplanned stoppages. During the period covered by this study (58 days), the total stoppage time was about 76.6 days and caused appreciable economic losses of about 2.3 million SEK.
TL;DR: The system was able to identify the presence of fault conditions with 100 percent accuracy on both lab and industrial data after minimal training; the accuracy of the fault classification (when trained to recognize multiple faults) was greater than 90 percent.
Abstract: Presents a real‐time neural network‐based condition monitoring system for rotating mechanical equipment. At its core is an ARTMAP neural network, which continually monitors machine vibration data, as it becomes available, in an effort to pinpoint new information about the machine condition. As new faults are encountered, the network weights can be automatically and incrementally adapted to incorporate information necessary to identify the fault in the future. Describes the design, operation, and performance of the diagnostic system. The system was able to identify the presence of fault conditions with 100 percent accuracy on both lab and industrial data after minimal training; the accuracy of the fault classification (when trained to recognize multiple faults) was greater than 90 percent.
TL;DR: In this article, a model based on the continuous time Markov chain where the rate of degradation of a system depends on the state of the system and the fact that different parameters that cause system degradation can be dependent is presented.
Abstract: Mathematical models for reliability prediction under multiple condition parameters are discussed. The models are developed under the assumption that the different condition parameters can be independent or dependent. Presents a model based on the continuous time Markov chain where the rate of degradation of the system depends on the state of the system and the fact that different parameters that cause system degradation can be dependent. The models are illustrated using an example.
TL;DR: The results of a survey of Canadian robot users concerning robot reliability and safety are presented, including the fact that approximately 75 per cent of companies are using robots for commercial purposes and most general types of robots used in industry are intelligent robots.
Abstract: This paper presents the results of a survey of Canadian robot users concerning robot reliability and safety. Data on 26 questions were analyzed and the resulting findings are presented in the form of tables, histograms, pie charts, etc. Provides conclusions including the fact that approximately 75 per cent of companies are using robots for commercial purposes; most general types of robots used in industry are intelligent robots; frequently ineffective maintenance manuals are provided by the robot manufacturers; and robot‐related problems are generally less than 50 per year.
TL;DR: In this paper, the prior uncertainty in the probabilities of failure per unit time is expressed in terms of a Dirichlet distribution, and Bayes estimates can be obtained of three cost-based criteria to compare maintenance decisions over unbounded time-horizons.
Abstract: Due to a lack of data, many maintenance optimisation models have to be initialised on the basis of expert judgment. Rather than eliciting the parameters of a continuous lifetime distribution, experts give more reliable answers when assessing a discrete lifetime distribution. If the prior uncertainty in the probabilities of failure per unit time is expressed in terms of a Dirichlet distribution, Bayes estimates can be obtained of three cost‐based criteria to compare maintenance decisions over unbounded time‐horizons: first, the expected average costs per unit time; second, the expected discounted costs over an unbounded horizon; and third, the expected equivalent average costs per unit time. Illustrates the maintenance model by determining optimal age replacement and lifecycle costing policies, which optimally balance both the failure cost against the preventive repair cost, and the initial cost against the future cost.
TL;DR: In this article, a set of maintenance strategies and a computerized Supervisory Control and Data Acquisition (SCADA) system for achieving an integrated maintenance management is described, which enables maintenance projects to be better controlled and resources to be properly utilised.
Abstract: In the majority of public utilities, achieving optimum utilisation of existing capital assets for meeting future predicted demand is a major function at all levels of management. In this paper, a set of maintenance strategies and a computerised Supervisory Control and Data Acquisition (SCADA) system for achieving an integrated maintenance management is described. The objective of the integrated system is to enable maintenance projects to be better controlled and resources to be properly utilised. A case study is used to illustrate the proposed maintenance strategies which include the identification of real time and historical data required to measure, visualise and quantify the progress of maintenance activities. Existing and proposed systems and procedures are analysed and discussed with major recommendations included for the design and implementation of this integrated system.
TL;DR: In this paper, a nonlinear model based on seemingly unrelated regression analysis is used to identify various factors that influence the maintenance expenditures of US chemical companies from 1975 to 1991, showing that the age of property, plant and equipment, and buildings, company size, and return on assets have significant influence on maintenance expenditures.
Abstract: Maintenance expenditures represent more than net profits of several manufacturing companies. Maintenance costs are easy to reduce in a year simply by deferring maintenance activities. Examines maintenance expenditures of US chemical companies from 1975 to 1991. Uses a nonlinear model based on seemingly unrelated regression analysis to identify various factors that influence the expenditures. Uses the ratios of maintenance spending to cost of property, plant and equipment, and buildings (gross plant), cost of property, plant and equipment, and buildings minus accumulated depreciation (net plant) and cost of goods sold as dependent variables. Shows that the age of property, plant and equipment, and buildings, company size, and return on assets have significant influence on the maintenance expenditures. The leverage ratios adversely affect the ratios of maintenance costs to gross plant and net plant.
TL;DR: In this paper, a proposed maintenance schedule can be obtained automatically by the adoption of genetic algorithm by determining the maintenance schedule of circuit outage with minimizing the maintenance cost and maximizing the circuit availability under certain unavoidable system constraints.
Abstract: An electrical company is responsible for the maintenance of a transmission network of high voltage electricity. The maintenance schedule must be planned so as to minimize outage costs, taking into consideration various factors such as system security/reliability, system availability, and manpower utilization. With the rapid growth of organization, planning engineers are required to fulfill additional roles in order to increase productivity. To this end, a fast response and accurate mechanism is required to assist the planning engineers in dealing with the daily operation. This paper describes how a proposed maintenance schedule can be obtained automatically by the adoption of genetic algorithm. The main aim is to determine the maintenance schedule of circuit outage with minimizing the maintenance cost and maximizing the circuit availability under certain unavoidable system constraints. Further, an additional search mechanism called “final tuning search” is developed to enhance the system performance.
TL;DR: In this paper, a system of equations relating to the combined noise level at each machine with the individual noise level and the intermachine distances is presented to detect a malfunctioned machine.
Abstract: Machine malfunction may be detected from the change in its noise level sensed by the ear or measured by a sound level meter. When various machines run concurrently in a workshop, it is not easy to detect noise change. This paper presents the development of a system of equations relating to the combined noise level at each machine with the individual noise level and the inter‐machine distances. A method is presented to detect a malfunctioned machine by solving a system of equations and a case study is included.