Showing papers on "Preventive maintenance published in 1990"

Manufacturing flow control and preventing maintenance: a stochastic control approach

Abstract: A stochastic control model for simultaneously planning production and maintenance in a flexible manufacturing system (FMS) is proposed, and an efficient technique for computing the optimal control policy is developed. The model extends previous formulations by including an age-dependent machine failure rate and by allowing the control to influence some jump rates (namely the preventive maintenance activities). By using an adaptation to the case of piecewise-deterministic systems of the approximation technique initially proposed by H.J. Kushner (1977) in the realm of the optimal control of diffusions, one shows how it is possible to computer the optimal control for a two-machine system. >

Reliability-centered maintenance: management and engineering methods

Abstract: In this book the authors provide a fresh look at basic reliability and maintainability engineering techniques and management tools for ap plication to the system maintenance planning and implementation process. The essential life-cycle reliability centered maintenance (ReM) activities are focused on maintenance planning and the prevention of failure. The premise is that more efficient, and therefore effective, life-cycle main tenance programs can be established using a well disciplined decision logic analysis process that addresses individual part failure modes, their consequences, and the actual preventive maintenance tasks. This premise and the techniques and tools described emphasize preventive, not corrective, maintenance. The authors also describe the techniques and tools fundamental to maintenance engineering. They provide an understanding of the inter relationships of the elements of a complete ReM program (which are applicable to any complex system or component and are not limited only to the aircraft industry). They describe special methodologies for improving the maintenance process. These include an on-condition maintenance (OeM) methodology to identify defects and potential deterioration which can determine what is needed as a maintenance action in order to prevent failure during use."

Optimal strategies for scheduling checkpoints and preventive maintenance

Abstract: At checkpoints during the operation of a computer, the state of the system is saved. Whenever a machine fails, it is repaired and then reset to the state saved at the latest checkpoint. In the present work, save times are known constants and repair times are random variables; failures are the epochs of a given renewal process. In scheduling the checkpoints, the cost of saves must be traded off against the cost of work lost when the computer fails. It is shown how to schedule checkpoints to minimize the mean total time to finish a given job. Similar optimization results are obtained for the tails of the distribution of the finishing time. Two variants of the basic model are considered. In one of the computer receives maintenance during each save; in the other it does not. Applications to the M/G/1 queuing system are touched on. >

Rout and seal cracks in flexible pavement--a cost-effective preventive maintenance procedure

Abstract: The Ministry of Transportation of Ontario conducted a comprehensive study on the feasibility of a rout and seal treatment of cracks in flexible pavement as a preventive maintenance procedure. The objectives of this study were to ascertain the cost-effectiveness of this procedure on the basis of the successful treatment of the distress, the resultant extension of pavement service life, and the optimum timing for application to achieve maximum cost benefit. Implemented in 1986 across the province of Ontario, the study ensures complete coverage of different climatic and environmental conditions. Monitoring of the treatment performance and pavement conditions has been completed for a period including three winters. From the data, it has been established that (a) certain rout configurations are more effective in different regions in the province, (b) the rout and seal treatment effectively delays or even stops progressive distress deterioration, and (c) the treatment is essential to achieve maximum cost benefit, with the optimum time being from the 3rd to 5th years for initial treatment, and the 8th to 9th years for follow-up treatment.

Resource-constrained capital budgeting model for bridge maintenance, rehabilitation, and replacement

Abstract: A mathematical formulation is presented for optimal allocation of a granted budget among a system of bridges that are under the jurisdiction of a transportation agency. The formulation is based on a 0-1 integer-linear programming algorithm with multiple-choice constraints. Three improvement alternatives are assumed possible for a bridge at any point in time--replacement, rehabilitation, and major maintenance. Provision is also made for routine preventive maintenance. The optimal alternatives are selected on the basis of the criterion of maximizing reductions in equivalent uniform annual costs to the ultimate owner, the user-taxpayer.

RETEST-development of a selective revalidation prototype environment for use in software maintenance

Abstract: The authors examine problems associated with regression testing, giving particular attention to aspects concerning selective revalidation. They describe a prototype retesting environment called RETEST that will allow maintenance personnel to cope with revalidation procedures. It is noted that large amounts of time and computational resources are expended for revalidation and that the maintainers' view of this topic often lacks a sensible and systematic approach. >

Towards a real—time knowledge-based simulation system for diagnosing machine tool failure

Abstract: A framework for diagnosing and characterizing the failure propagation of various components in a CNC (computer numerical control) machine tool using real-time knowledge-based simulation is discussed. The input data necessary for conducting simulation are obtained from a knowledge base structured using frames. Preventive maintenance and sudden failures are modeled. The implemented system provides an integrated environment for the maintenance supervisors to obtain early warnings about the expected failure times of different components and the stoppage time of the machine tool. The system also provides the capability of identifying the critical components susceptible to frequent failures. >

FLEET: Equipment Management System

Abstract: The contractor’s equipment policy and equipment management system have a great impact on the profitability of the firm, especially for contractors with large investments in equipment. An equipment management system, FLEET, is presented. FLEET consists of four modules: (1) Inventory management module; (2) cost, time, and production records module; (3) maintenance management module; and (4) report generator module. Inventory management module effectively houses the inventory data for the equipment including equipment number, description, serial number, manufacturer, purchase date, purchase price, service life, market value, and custodian. Cost, time, and production records module houses the cost, time, and production data for the equipment including date, equipment number, job name, hourly charge rate, depreciation, insurance, interest, and taxes (IIT), storage cost, fuel, oil, and grease (FOG), tire/track, maintenance and repair service, operating labor, overhead, operating hours, downtiem, idle time, and production. These statistics are accumulated and summarized in a master file. Maintenance management module consists of a set of files to record and schedule preventive maintenance for different pieces of equipment and for different types of maintenance and a set of maintenance history files to store past maintenance records for each piece of equipment including preventive maintenance, field/shop repairs, and overhauls. The data entered through the other three modules is accessed through the report generator module to produce appropriate reports necessary to make effective management decisions and to keep abreast of daily activities. Development, acceptance, and continued use of such systems should contribute to the efficiency and profitability of contractors.

A Practical Guide to Maintenance Engineering

Abstract: Equipment register planned and preventative maintenance maintenance defect monitoring maintenance stores spares part monitoring statutory inspection monitoring maintenance vibration analysis maintenance management.

Practice case study

Abstract: This case study demonstrates how simple changes in the way maintenance is managed can result in significant benefits, improving productivity and performance. It describes the work carried out by a major U.K. services organization and was contracted to provide support and maintenance services for one of their key business systems.

RAM analysis helps cut turbine-generator systems costs

Abstract: Maintenance is effective when it improves equipment availability and reduces costs. Reduced costs stem from increased availability, which is the primary objective of this study. As a result, overall operating costs decrease. RAM analysis requires a logical approach to the problem through the use of techniques such as FMEA, FTA and goal trees. To illustrate the steps of this method, the authors used a simplified T-G system. This method is to rank critical components in terms of the severity of failure. On the basis of ranking, it is possible to assign the preventive maintenance tasks in order of priority. Other options are available. Examples are revised procedures, more detailed outage plans using PC-based programs and better spare parts management.

Computer‐based planned maintenance programmes

Abstract: Reviews the growth in importance of planned maintenance programming (PMP). Sets out the aims of computerising PMP at strategic and detailed levels. Provides a detailed analysis of successful systems characteristics. Lists considerations to be borne in mind and questions to ask before purchasing a system. Concludes that although the potential benefits of computerised PMP are great, careful consideration of the objectives and options is vital.

Preventive maintenance can be more effective than predictive programs

Abstract: The authors discuss how a carefully chosen, periodically implemented, preventive maintenance (PM) program can sometimes make more economic sense than predictive maintenance because not all equipment responds to purely predictive techniques. Predictive maintenance uses projected data or trends to determine the trouble-free service life of equipment. In contrast, preventive maintenance is doing the minimal routine work necessary to ensure the equipment remains in proper operating condition.

Optimum maintenance policies maximizing service reliability

Abstract: A system is considered which undergoes both repair and preventive maintenance (PM) and optimum policies maximizing service reliability are discussed. A discrete case is also considered and a more general measure of service reliability is proposed.

Preventive maintenance expert system

Abstract: PURPOSE:To unbiasedly calculate the remaining service life of an apparatus with sufficient accuracy for practical use and to perform the preventive maintenance of a plant by coupling optimumly a formulated remaining service life evaluating arithmetic expression and empirical knowledge of plural experts, and diagnosing appropriately the remaining service life. CONSTITUTION:With respect to an object apparatus or parts whose remaining service life is calculated, necessary information is obtained from a memory 2 and a plant data collecting device 3. Subsequently, based on a difference between a condition obtained by formulating a remaining service life arithmetic expression and an actual operating condition, or a variance of the apparatus and the parts, etc., how much a coefficient of a remaining service life arithmetic expression which is not shown in the figure is to be corrected is calculated by using the knowledge of an expert. By repeating the foregoing, the remaining service life is calculated with regard to all the object apparatuses, and thereafter, a necessary item for the maintenance is outputted to an output device 4.

Controlling ductile-iron water main corrosion : a preventive maintenance program

Abstract: The corrosion-related premature failure of ductile-iron water main piping is a significant problem for many Canadian cities. The first failures in the city of Scarborough occurred after the pipe had only been in service for seven years, and the rate of failure continued to increase until a cathodic protection program was implemented. This article describes the preventive maintenance program designed to combat the problem of ductile-iron water main failures. This program includes soil sampling, pre- and post-installation surveys, the installation of cathodic protection using sacrificial anodes, and record keeping. The issue of standards for new installations is also addressed

Oil station system

Abstract: PURPOSE:To contrive the managed and preventive maintenance of all the parts of a weigher with accuracy in order to improve oil feeding accuracy by providing a common maintenance managing means which receives the oil feed information exchanged between the weigher and a POS terminal unit and which provides all the kinds of maintenance data obtained by computation made according to the maintenance status of the weigher based on the oil feed information. CONSTITUTION:A common maintenance managing means 3 receives the oil feed information exchanged between a weigher 7 and a POS terminal unit 2 and, based on such information, provides all kinds of maintenance data obtained by computation made according to the maintenance status of the weigher 7. The maintenance data regarding the weigher 7 include the number of oil feed times, the operating time of a pump 8, current application time and preset oil feed accuracy. Due to the ability of the weigher 7 to manage the maintenance accurately, therefore, the improvement of the preventive maintenance and reliability of the subject system can be attained and an accurate stock control of the maintenance parts can be performed. Since the oil feed accuracy of the weigher 7 is being monitored, in case of malfunction, a prompt maintenance can be done, thus offering an appropriately managed maintenance work.

Meeting Issues of Preventive Maintenance for New York City Bridges

Abstract: During 1988–1989, a consortium of civil engineering departments of New York City colleges and universities administered by the Center for Infrastructure Studies at Columbia University undertook the development of a preventive maintenance management system for the Department of Transportation in the City of New York. The participating schools were: Columbia University, City College, Cooper Union, Polytechnic University, and Pratt Institute. The system that was developed covered a total of 1,426 bridges. The system concentrates on those bridges in “good” or “very good” condition although it makes it clear that preventive maintenance must also be performed on “fair” and “poor” bridges until a steady state is reached. The study established the requirements to protect the bridges through dirt and water control, steel protection, roadway surface maintenance, maintaining mechanical and electrical components on moveable bridges, and performing special requirements on the East River bridges. A computer system for ...

Overall preventive maintenance system for plant

Abstract: PURPOSE:To keep the operating efficiency of a plant high and to decide its optimized maintenance precedence by estimating a residual service life of each equipment or device of the plant and by providing a device for judging its effect occurring at the end of its service life and its maintenance precedence. CONSTITUTION:Based upon a predetermined rule, equipments and devices which are subjected to a diagonosis are selected; their operational and environmental condition data and so on are taken in from a data base DB 5; their residual service life after that time is diagonosed based upon a predetermined residual service life algorithm in a residual service life diagonosis means 1. It is judged which component part or element reaches the end of its service life earliest, its failure modes are judged 2 based upon results of the previous judgement, and when a failure occurs, its influence on a whole plant is judged with data of the database 5. On the other hand, based upon another predetermined rule, maintenance precedence is decided and output. The above-mentioned process is applied to all the equipments and devices according to a schedule. In this way, a foundamental maintenance of the equipments and devices can be executed in advance to ends of their service lives, so that the operating efficiency of the plant can be kept at an economically high level.

Preventive maintenance system

Abstract: PURPOSE:To speedily execute soundness evaluation and remaining life evaluation, to easily process a check item and the items of repair, exchange and reconstruction to be presented at the time of next periodical check and to execute preventive maintenance by executing data processing like a system based on outputs from a soundness evaluating means and a remaining life evaluating means. CONSTITUTION:A soundness evaluating means 4 to evaluate soundness from an operation history 2a in the past of parts, which constitute a preventive maintenance object equipment, and remaining life evaluating means 2b and 2b' to execute degradation diagnosis concerning the degrading part of this object equipment and to evaluate a remaining life are provided. Based on the outputs from this soundness evaluating means 4 and the remaining life evaluating means 2b and 2b', the check item and the items of the repair, exchange and reconstruction to be needed at the time of the next periodical check are decided as a preventive maintenance item 5 and outputted as a table 6. Thus, labor is reduced at a minimum and the preventive maintenance item and an executing time can be exactly obtained without fail.

Models for optimal maintenance of hydraulic structures

Abstract: Corrective maintenance includes the unscheduled repairs required to return a structure from a failed state to an operating or available state. Corrective maintenance is determined by the reliability of the structure. Preventive maintenance includes scheduled action to retain a structure in an operational or available state by preventing failures from occurring. Preventive maintenance directly affects reliability. The trade-offs between the costs for corrective and preventive maintenance are shown. An economic objective to determine the optimum level of maintenance would be to determine the total minimum cost. This objective is discussed in the paper, along with other aspects of the subject.

Microcomputer management & maintenance for libraries

Abstract: Part 1 Managing microcomputer facilities in libraries: introduction to managing microcomputer facilities in libraries the planning process - the planning team, information sources, library visits, planning and needs assessment, timetables, documenting the plan, bringing the plan to life needs assessment - management and clerical needs, library automation needs, public access needs, networking and compatibility needs, needs assessment process system requirements - identification of available resources, definition of requirements system evaluation - microcomputer components, peripheral devices cost/benefit analysis - expenses, return on investment purchase and installation - selection of vendors, preparation for installation, installing the equipment orientation and training - resistance to change, pre-installation orientation, in-house vs. outside training, training for administrative operations, training for library-specific operations, training for public access operations keeping it running - staff responsibilities, setting policies, record-keeping procedures. Part 2 Maintaining microcomputer facilities in libraries: introduction to maintaining microcomputer facilities in libraries preventive maintenance - tools, environment, hardware, disks and stored data files responsive maintenance - hardware, disks and stored data files maintenance costs - in-house maintenance, evaluation repair facilities, service contracts.

Condition-based maintenance in the FMMS environment

Abstract: Following the installation of a Flexible Milling Manufacturing System at British Aerospace, Brough, it became obvious that new maintenance policies would have to be devised. Using the information gained on similar machines over the previous three years, combined with the results of a year’s trials on proprietary monitoring equipment, it was decided to adopt a mixed policy of preventative and condition based maintenance.

Deposit control: an essential step in preventive maintenance

Abstract: On discute des problemes de depots dans les circuits de machines a papier et des moyens de prevention

Condition monitoring based maintenance in practice in a heavy chemical plant

Abstract: At the outset, let me thank you on behalf of our company, John and myself for this opportunity. As the title suggests we are going to talk about the practical aspects of condition monitoring in the overall maintenance management of the largest heavy process plant in Ireland.