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  • International Journal of Industrial Engineering Research and Development (IJIERD), ISSN 0976 – INTERNATIONAL JOURNAL OF INDUSTRIAL ENGINEERING 6979(Print), ISSN 0976 – 6987(Online), Volume 5, Issue 1, January - February (2014), © IAEME RESEARCH AND DEVELOPMENT (IJIERD) ISSN 0976 – 6979 (Print) ISSN 0976 – 6987 (Online) Volume 5, Issue 1, January - February (2014), pp. 10-30 © IAEME: www.iaeme.com/ijierd.asp Journal Impact Factor (2013): 5.1283 (Calculated by GISI) www.jifactor.com IJIERD ©IAEME STUDY RELIABILITY CENTERED MAINTENANCE (RCM) OF ROTATING EQUIPMENT THROUGH PREDICTIVE MAINTENANCE Mariam Altaf Tarar Lecturer, Institute of Quality & Technology Management, University of the Punjab, Lahore, Pakistan ABSTRACT Reliability Centered Maintenance (RCM) is the framework of preserving system functions, rather than preserving physical asset. RCM is used to evaluate planned maintenance schedule that will offers availability of equipment with both reliability and maintainability. This paper presents ABC Automobile Company case, where planned maintenance is possible with application of predictive maintenance strategy, which enables to take decision of maintenance action with evidence and reduce unneeded maintenance. The main principle of predictive maintenance is examining the important performance characteristics of equipment to select the most indicative parameters of condition which reflects functional failures. In proposals, vibration is selected as an important performance characteristic of rotating components. Through vibration monitoring several mechanical failures can be effectively predicted. Signals (such as through the use of vibration monitoring) emanating from the condition monitoring of equipment are frequently interpretative as per manufacturer’s recommendations, use of an expert system, or the threshold values established through the experience of inspectors are used (Wiseman and Jardine, 1999). The maintenance strategy adopted by ABC Automobile Company is preventive maintenance with manually collected condition monitoring data. That data usually indicates abnormality when actually failure occurs. This paper includes determination of the effectiveness of existing maintenance strategy and its comparisons with other strategies with improvement proposals. It outlines RCM analysis process and a test case of fans of paint booth process. This study concludes that RCM enables to evaluate planned maintenance action and incase of rotating components the vibration monitoring technique can be effectively used in predictive maintenance strategy. The paper reveals that the ABC Automobile Company can 10
  • International Journal of Industrial Engineering Research and Development (IJIERD), ISSN 0976 – 6979(Print), ISSN 0976 – 6987(Online), Volume 5, Issue 1, January - February (2014), © IAEME achieve enhanced manufacturing performance leading to competitive advantage with successful RCM implementation through predictive maintenance. Keywords: Reliability Centered Maintenance (RCM), Predictive Maintenance, Preventive maintenance, Condition monitoring, Performance monitoring, Vibration monitoring. 1.2 Background Maintenance is routine recurring work, which is necessary to retain equipment in a state in which it can perform its intended function. Maintenance is performed to ensure equipment availability in industry so as to compete in global market. Maintenance has changed more than any other management discipline during the past twenty years. In early ages, the maintenance strategy was breakdown maintenance, as there was no awareness of downtime. But with passage of time, increased complexity of machines led to the prevention maintenance in second generation, and then maintenance strategies and objectives have rapidly changed from preventive maintenance to condition monitoring. In this era, the importance of effectiveness of operational equipment raised, which is dependent on plant capacity (Raouf, 2004). So, the concluded strategy must have a balance between maintenance cost and plant reliability. Usually most of the industries in Pakistan follow preventive maintenance strategy or scheduled maintenance. According to Herbaty, Preventive maintenance comprises of periodic activities performed at predetermined time interval or after the specified amount of equipment usage to keep it in proper working condition and to prevent it from breakdowns (Herbaty, 1990). In 1960s, a new concept, Reliability Centered Maintenance (RCM) evolved. Initially RCM was used in aircraft industries, and it was oriented towards airplanes maintenance (Dekker, 1996). RCM is a structured framework and a logical process of optimizing maintenance resources for physical asset’s maintenance in its operating context. RCM is focused on preserving system functions, rather than preserving physical asset. RCM analyzes the functions, potential failures of equipment and it is a seven-review step philosophy to evaluate “inherent reliability”, with risk management. RCM is possible with the selection of an effective maintenance strategy that will offer “inherent reliability” of equipment (Samanta et al., 2001). 1.3 Problem Statement In preventive or routine maintenance of equipment, catastrophic failures are still likely to occur; maintenance may be performed more often than may be necessary; in such unneeded maintenance there are chances of components incidental damage; assets taken offline often for maintenance services, and was mostly labor intensive. In ABC Automobile Company, preventive maintenance is followed with actions of cleaning, lubrication, tightening, adjustment, and parts replacement at specified time interval. Sometimes unneeded preventive maintenance actions are performed, and just performed to fulfill schedule demand. For such maintenance activities, equipment is taken off line and these activities are usually labor intensive. Secondly, ABC Automobile Company daily collects condition monitoring data. That data are based on manual checking or observing. That is why data do not indicate any upper or lower limit of any parameters. It indicates abnormality when actually failure occurs. The pitfall of this method is the daily monitoring i.e. every 3hours that require extra manpower to check and handle this manually collected inappropriate data. 11
  • International Journal of Industrial Engineering Research and Development (IJIERD), ISSN 0976 – 6979(Print), ISSN 0976 – 6987(Online), Volume 5, Issue 1, January - February (2014), © IAEME In case of critical equipment, preventive maintenance activities are hard to schedule so any other strategy can be more economical. The strategy through that may be beneficial is the one in which maintenance is performed only when necessary and thus it will provide better asset availability and reliability. 1.4 Objective The objective of this paper is to study predictive maintenance strategy and the benefits of its implementation for the equipment at ABC Automobile Company, instead of preventive maintenance. This study focuses on rotating equipment (e.g. motors, pumps, conveyors, compressors etc.), where vibration monitoring can be implemented through RCM. 1.5 Gap Analysis In ABC Automobile Company, preventive maintenance strategy is followed on the basis of schedule activities at the specified time intervals. So there is a margin to improve through application of Reliability Centered Maintenance (RCM). This improvement is possible with predictive maintenance requirements instead of carrying out routine or scheduled maintenance. Performance parameters and other condition monitoring parameters can be identified and analyzed to find out the root cause of failure. As these performance parameters and other condition monitoring parameters are the indicators of equipment condition and performance decline. So, their analysis will provide the optimum time to plan and perform maintenance action before failure occurs. It will facilitate maintenance staff in decision making by providing evidence. 1.6 Significance of the Research This paper is based on ABC Automobile Company existing maintenance strategy, and its improvement proposal through RCM. For this purpose, an exhaustive and logical search of maintenance literature is conducted, evaluated different maintenance strategies and their comparison with each other. This comparison helps to select an appropriate maintenance strategy for critical and non critical equipment. It will discuss implementation plan of RCM through predictive maintenance, and also shows a test case of critical equipment to find out root cause of the decline in performance. 1.7 Methodology The research approach is qualitative and primary data sources are used to collect data. The method of data collection is observation (non-participant) and structured interviewing of maintenance staff of ABC Automobile Company Ltd and condition monitoring Company. This study primarily describes their existing situation and problems facing with preventive maintenance strategy on account of the different opinions people have about an issue and observations, and data analysis with proposals to improve this situation. A test case is presented to analyze the validity of proposals to improve this situation. 2.1 Existing Condition Monitoring Data In ABC Automobile Company, preventive maintenance is followed with manual daily condition monitoring of sheets. Few of the critical equipment’s monitoring parameters are shown below with their standard ratings; 12
  • International Journal of Industrial Engineering Research and Development (IJIERD), ISSN 0976 – 6979(Print), ISSN 0976 – 6987(Online), Volume 5, Issue 1, January - February (2014), © IAEME Table 1: Existing Condition monitoring data Equipment: PO Booth # 1 Exh. Fan SubEquipment Monitoring Items Standard Rating Exh. Fan Spray Booth Exh. Fan Setting Room Noise Vibra B.Con. B.Noise Noise Vibra B. Noise None None T~N~L None None None None B.Noise None Equipment: Top Coat Booth # 1 Fans SubEquipment Clear Coat# 2 Exhaust Fan Setting Room Exhaust Fan Monitoring Items Noise Vibr. B. Noise B. Cond. Noise Vibr. B. Noise B. Cond. Standard Rating None None None T~N~L None None None T~N~L Moisture Trap of compressor Manual Drain Equipment: New Small Compressor SubEquipment Motor Noise Compressor Tension Level Air tank Moisture Trap of Man Tank Open Pressure Noise Manual Drain Oil Monitoring Items Belt I/P Valves Of Tank Equipment: Cooling Water Circulation System CWP 01 A CWP 03 BA CWP 03 B SubEquipment Pump Bearing Motor Bearing Motor Cool Fan Pump Bearing Motor Bearing Motor Cool Fan Pump & Motor Bearing Motor Cool Fan Monitoring Items Noise Noise Loose Noise Noise Loose Noise Loose Standard Rating None None None None None None None None Legends : OK=O,NG=X, Vibra.=Vibration, B.Con.= Belt Condition, T~N~L= Tight~Normal~Loose, B.Noise=Bearing Noise. In Table 1, noise, vibration, belt looseness and bearing noise of paint Booth # 1 Exhaust fan is monitored on basis of manual observation of maintenance staff, which is attribute data and not clarifying quantitative data of these parameters. So it is not guaranteed to predict equipment condition. Similar inspection is followed in case of new small compressor and cooling water circulation system. 2.2 Analysis of existing Maintenance strategy With the existing way of monitoring parameters, it is unable to predict failure accurately. The data of vibration or noise are based on manual checking or hearing. That is why data are not indicating any upper or lower limit of these parameters. It indicates 13
  • International Journal of Industrial Engineering Research and Development (IJIERD), ISSN 0976 – 6979(Print), ISSN 0976 – 6987(Online), Volume 5, Issue 1, January - February (2014), © IAEME abnormality when actually failure occurs. The pitfall of this method is the daily monitoring occurs. every 3hours that require extra manpower to check and handle this manually collected inappropriate data. As shown in Table 1, noise, vibration, belt looseness and bearing noise of paint Booth # 1 Exhaust fan is monitored on basis of manual observation of maintenance haust staff, which is not guaranteed to predict equipment condition. Similar inspection is followed in case of other equipment as shown in Table 1. When failure of critical equipment is focused and analyzed then it is concluded that focused many mechanical failures can be ignored and predict timely, in case of proper health monitoring of rotating equipment. 2.3 Proposed Maintenance Action Plan On rotating equipment, predictive maintenance is a suitable strategy to prevent suitable failures of particular equipment and control proper working of the whole station. So, machines and optimum monitoring techniques are selected and predictive maintenance can be followed. With the help of condition monitoring of particular rotating components, through particular vibration monitoring equipment, their scheduled maintenance can be planned as per requirement of machine. The implementation of Predictive maintenance in addition to preventive maintenance is possible with the following steps; g 1. Classify equipment for maintenance, 2. Select RCM strategy, 3. Implementation of Predictive maintenance. 2.3.1 Classify equipment for maintenance First step in implementing RCM is to select or classify equipment for appropriate maintenance strategy. The two methods used to select equipment are Criticality Analysis and Selection Question method that is usually employed. Figure 1: Classifying Equipment for maintenance 14
  • International Journal of Industrial Engineering Research and Development (IJIERD), ISSN 0976 – 6979(Print), ISSN 0976 – 6987(Online), Volume 5, Issue 1, January - February (2014), © IAEME 2.3.2 Comparison of Maintenance Strategies The following Table 2 summarizes the differences between a numbers of maintenance strategies: Table 2: Comparison of Maintenance strategies Maintenan ce Strategy Maintenance Strategy Brief Concept Maintenance Approach Frequency of Maintenance Criteria for initiating Maintenance Reactive Repair actions are performed after the failure occurs and people wait until equipment fails, and then maintenance actions focused to quickly make possible the availability of equipment. Fix it when it breaks Unscheduled/ unplanned Upon failure, work stoppage to fix problem immediately Not usually Large maintenance budget Unpredictabl e asset availability and reliability Preventive In PM, maintenance performed before failure occurs, for equipment in which downtime costs more than preventing incipient failure. Schedule maintenance Pre scheduled / pre planned Prescribed based on failure history or test data. Not usually but sometimes manually collected Periodic component replacement/ repair. Maintenance performed more often than may be necessary. In PdM, indicators show the requirement of maintenance actions to take. So it is a type of maintenance performed on the basis of requirement of machine. Repair prior to failure when needed It is performed as per requirement and use sophisticated equipments to detect signs of imminent failure. So maintenance is performed when need arises. Repair prior to failure condition based Predictive Condition Based Condition Assessment Significance & Techniques needed To prevent operation problems that lead to failure. Just in time ( planned) Scheduled as per need Prescribed based on statistical patterns in operating parameters. Assets often taken off-line time for service. Periodic sample data collection. Monitoring condition by vibration, heat, alignment, wear debris etc. To prevent operation problems that lead to failure or reduced throughput. Just in time ( planned) Prescribed based on statistical patterns in operating parameters. To prevent operation problems that lead to failure or reduced throughput 15 Results Continuous/ real time sensor monitoring and data collection. Monitoring condition by vibration, heat, alignment, wear debris etc. Maintenance performed when necessary. Better asset availability and reliability. Maintenance performed when necessary. Highest asset availability and reliability. It is an online monitoring system, and generally continuous.
  • International Journal of Industrial Engineering Research and Development (IJIERD), ISSN 0976 – 6979(Print), ISSN 0976 – 6987(Online), Volume 5, Issue 1, January - February (2014), © IAEME 2.3.3 Select RCM strategy There are four components of RCM program which are, • Reactive Maintenance • Preventive Maintenance • Predictive Maintenance • Proactive Maintenance. Predictive maintenance is an extension of preventive maintenance, but offers timely failure detection of in-service machine, reduce failure severity and frequency, minimize overall cost of maintenance, and improve operational safety. The selected maintenance strategy is predictive maintenance in addition to preventive maintenance. It can be implemented through two methods (Amik Garg et al., 2006); 1. Performance monitoring, 2. Monitoring through Diagnostic equipment. As discussed above that, for critical components preventive maintenance is insufficient to control failure, so any predictive maintenance technique is recommended. There are many parameters which can be measured and analyzed to predict imminent failure and monitor health of equipment. Monitoring through Diagnostic equipment enable us to monitor; • Machine vibration • Wear debris analysis • Infrared thermography • Laser alignment • Oil analysis • Noise survey Secondly, operating characteristics or performance parameters can help out in detecting problems such as; • Variation in Flow rates • Pressure/temperature differences • Comparison ratios • Cycle efficiencies • Variation in production rate • Variation in product quality • Efficiency, etc 16
  • International Journal of Industrial Engineering Research and Development (IJIERD), ISSN 0976 – 6979(Print), ISSN 0976 – 6987(Online), Volume 5, Issue 1, January - February (2014), © IAEME Fig 2 Flowchart of Selected Predictive Maintenance Techniques 2.3.4 Implementation of Predictive maintenance The Predictive maintenance can be implemented in three distinct stages; 1. Detection 2. Analysis 3. Correction In initial phase, it involves a detailed survey of the plant and its equipment. Then critical and non critical equipment is classified and an RCM strategy is selected which is appropriate for improving reliability and availability of these equipment. In case of predictive maintenance, parameters are selected to monitor health of machines. Acceptable condit conditions (limits) are set and to collect data to record and analyze data. Detection means identifying any abnormality in collected data of a particular parameter. It involves measuring and trend analysis at marked points on each machine on a regular (scheduled) basis. Analysis helps to (scheduled) find out the root cause of the abnormality detected. It is basically a diagnosis of machine problem, so that corrective action can be taken. Corrective action can be easily planned to keep machine downtime at an absolute minimum. Its implementation’s main objective is to alarm about developing problems. The below flowchart illustrates each step clearly; 17
  • International Journal of Industrial Engineering Research and Development (IJIERD), ISSN 0976 – 6979(Print), ISSN 0976 – 6987(Online), Volume 5, Issue 1, January - February (2014), © IAEME PLANT SURVEY CLASSIFYING EQUIPMENTS CRITICAL EQUIPMENT NO SELECT PREVENTIVE MAINTENANCE YES SELECT PREDICTIVE MAINTENANCE SELECT PARAMETERS TO MONITOR SET ACCEPTABLE CONDITION LIMITS COLLECT DATA TREND ANALYSIS OF FAULT DETECTION CONDITION ANALYSIS & ROOT CAUSE FINDING REMEDIAL ACTION Fig 3: Flowchart for Implementation of Predictive Maintenance 2.3.5 Selection of Vibration Analysis Vibration is the dominant characteristic which exists in almost all machines and is said to be the heartbeat of all mechanical equipment. Its information allows analysts to become aware of technical condition of a machine and to diagnose its ailments, especially in case of rotating equipment such as: gearboxes, fans, shafts, motors, compressors, pumps, mixers, driers. Simply measuring amplitude and frequency of vibration helps to detect machine problem and its root cause. Aim of vibration monitoring is to collect data automatically and transmit it to specialist for analysis so that an early identification and correction of potential machinery problems is possible. When machine vibration increases beyond its acceptable limits, the usual reason in any machine are unbalance, misalignment, worn parts, looseness, etc. 18
  • International Journal of Industrial Engineering Research and Development (IJIERD), ISSN 0976 – 6979(Print), ISSN 0976 – 6987(Online), Volume 5, Issue 1, January - February (2014), © IAEME Vibration monitoring requires higher start up investment cost for instruments and skill development of maintenance personnel, but it is in-service powerful information source for detecting imminent failure and monitoring machine health. It is easy to record data and transfer it to analyze, with portable and versatile instruments. It has accuracy to diagnose problem and permits effective planning of corrective action, planned shutdown time, skilled maintenance personnel and spare parts requirement. According to survey data of American Society of Mechanical Engineers (ASME), upto 82 percent of malfunctions of the mechanical equipment can be detected with the help of vibro-monitoring and vibro-diagnostic methods. (Parida et al., 2000) 2.5 Summary In ABC Automobile Company, preventive maintenance system enables it to prevent malfunctioning of critical equipment. In this system, condition monitoring of critical equipment is performed through manually collected data on the basis of senses of sight, smell, touch and hearing. For example the data of Paint booth fans just shows whether abnormal noise exists or not. This system has limitation of actual parameter measurement and authenticity of information. Secondly it enables to alarm or indicate imminent failure and to take remedial action before failure occurs. After the deep analysis with the help of RCM, it is concluded to follow predictive maintenance system for critical equipment. In plant survey, equipment are classified into critical and non critical categories and then proposed predictive maintenance for critical components. For predictive maintenance, parameters are selected for each machine, and to collect data and analyze. This analysis or trend data indicates imminent failure and give alarms to take remedial action before failure occurs. Predictive maintenance basically focuses on the future problem and helps to monitor condition on-line. This on line condition monitoring helps to perform well planned maintenance tasks and eliminates consequential losses. Through this system ABC Automobile Company cannot perform unneeded maintenance and reduces overall maintenance cost. To check the validity of the proposal a test case is taken of Paint Booth process and vibration monitoring technique used on its fans to collect data to predict imminent failure. Test Case: Step # 1 Equipment Selection The car paint process is important not only in aesthetic aspects of car but also it has direct impact on the business. Car Paint quality cannot be compromised because it is an integral feature of a business to generate repeated sales. The purpose of paint is to get smooth, uniform and shiny coats which can withstand extreme conditions of sunlight, rain or dust and tends to last long. So the paint booth process plays vital role to fulfill all requirements of finishing process, as given below. • • • Shiny and glamorous look, corrosion and rust prevention, Resistant to fading due to sun and ultraviolet rays, In process of Painting and Drying Spray booth plays an important role where the selected critical components are fans. In Painting and Drying Spray booth the vehicle is painted through a spray gun with air channel, which works under low pressure, followed by drying. The ceiling filter system derives air from outside of the facility, into the booth. Paint 19
  • International Journal of Industrial Engineering Research and Development (IJIERD), ISSN 0976 – 6979(Print), ISSN 0976 – 6987(Online), Volume 5, Issue 1, January - February (2014), © IAEME stop filters hold paint particles which are decomposed from air. Spray booth contains diesel burner and fan-motor units. A channel connection to units for air circulation is executed and motor circulation installed on the facility floor. The most important and critical function of a spray booth is managing its airflow maintaining uniform velocity in unidirectional layers. The managed airflow results in two advantages, • • Maximum efficiency of the paint sprayed in the Paint booth, And improved finish quality through directing overspray away from the painted finish. Air supply house supplies air to the booth after conditioning and filtering, minimizing temperature variations and removing particulates that compromise finish quality. Intake air moving across the painting operation conveys the overspray into the water curtain and the water wash apparatus, which then works to move the water in such a way as to trap and separate the particulate from the recycling water. articulate Process flow of paint booth is shown in fig 5, with sequence of operation and sequence of equipment. Fig 5: Process flow of paint booth 5 20
  • International Journal of Industrial Engineering Research and Development (IJIERD), ISSN 0976 – 6979(Print), ISSN 0976 – 6987(Online), Volume 5, Issue 1, January - February (2014), © IAEME Step # 2 RCM Process Seven Questions & Answers 1. What are the functions and associated desired standards of performance of the asset in its present operating context (functions)? Delivery of air into the booth or circulation of it is provided by fans, having the capacity of 360 m³ / min. In this unit air is delivered to the booth after being filtered by a pre-filter. Additionally output air is controlled by a damper in the output air channel. 1. In what ways can it fail to fulfill its functions (functional failures)? Table 3: Functional failures Function Function Failure Delivery of the air into the booth or circulation of it is provided by fans while meeting all quality, health, safety, and environmental standards. 1. Unable to rotate at 1460 rpm 2. Unable to meet quality standards 3. Unable to meet health, safety, and environmental standards. 2. What causes each functional failure (failure modes)? Vibration is due to the repeating forces in machines which are mostly due to the rotation of imbalanced and misaligned parts and may be due to the following, • Looseness • Contamination • Oil condition • Wear and tear • Defective bearing 3. What happens when each failure occurs (failure effects)? Failure may have following effects; • Broken, deformed, corroded or dirty fan blades. • Fan may trip • Machine unavailability • Unnecessary maintenance at predetermined schedules to adjust and replace parts regardless of whether or not the machines are malfunctioning • Quality problems when machine is running, which apparently seem functioning normally, but actually running into trouble and may have yielded losses rework costs, or worse still, warranty returns by customers. 4. In what way does each failure matter (failure consequences)? Failure may have following effects; • High Power Consumption, as machine that is vibrating consumes more power. • Cost of lost production • Cost of emergency spares procurement • Cost of maintenance and additional overheads • Delayed Shipment resulting in customer dissatisfaction • Accumulation of unfinished goods or WIP (work in process) 21
  • International Journal of Industrial Engineering Research and Development (IJIERD), ISSN 0976 – 6979(Print), ISSN 0976 – 6987(Online), Volume 5, Issue 1, January - February (2014), © IAEME • • Bad company image will be associated with shipment delays and poor quality Occupational hazards and human discomfort 5. What should be done to predict or prevent each failure (proactive tasks and task intervals)? Monitoring the vibration characteristics of a machine gives us an understanding of the ‘health’ condition of the machine. We can use this information to detect problems that might be developing. Operating a machine until it breaks down might be acceptable if the machine was a ‘disposable’ one. Most machines, however, are not ‘disposable’ due to their cost. 6. What should be done if a suitable proactive task cannot be found (default actions)? Default actions are may be routine preventive maintenance at predetermined schedules and cleaning of fan blades or allowed to breakdown. This RCM seven Question process helps to determine the causes of system failures and develop activities targeted to prevent them. The questions are designed to focus on maintaining the required functions of the system and help to conclude proactive maintenance strategy. The answers of first four questions, which are related to functional failure, causes and effects, are recorded in RCM information sheet as shown in table 4. In table 5 answers of remaining question is recorded which is decision worksheet. Decision worksheet is recorded with the help of answering question in RCM decision diagram related to failure consequences, preventive tasks and default actions as shown in Fig 6. Table 4: RCM information worksheet RCM information Worksheet Sr. Function no 1) Delivery of the air into the booth or circulation of it is provided by fans while meeting all quality, health, safety, and environmental standards. Functional failure A) Unable to rotate at 1460 rpm Unable to meet quality standards Unit: Paint Booth Component: Fans Failure mode a) Looseness b) Contamination c) Oil condition d) Wear and tear Unable to meet health, safety, and environmental standards. e) Defective bearing 22 Failure effect Broken, deformed, corroded or dirty fan blades. Fan may trip Machine. Unavailability. Unnecessary maintenance at predetermined schedules to adjust and replace parts regardless of whether or not the machines are malfunctioning. Quality problems when machine is running, it appears to be functioning normally, but into trouble and may have yielded losses, rework costs, or worse still, warranty returns by customers.
  • International Journal of Industrial Engineering Research and Development (IJIERD), ISSN 0976 – 6979(Print), ISSN 0976 – 6987(Online), Volume 5, Issue 1, January - February (2014), © IAEME Fig 6: RCM decision diagram (V.S Deshpande et al., 2003) Fig 7: Failure consequences summary (V.S Deshpande et al., 2003) 23
  • International Journal of Industrial Engineering Research and Development (IJIERD), ISSN 0976 – 6979(Print), ISSN 0976 – 6987(Online), Volume 5, Issue 1, January - February (2014), © IAEME Table 5: RCM decision worksheet RCM decision Worksheet Information reference F 1 FF A Consequence evaluation O Unit: Paint Booth Component: Fans H1 H2 H3 Default S1 S2 S3 action O1 O2 O3 FM H S E N1 N2 (a) Y N N Y N (b) N N N Y (c) N N (d) N (e) N Proposed Task N3 H4 H5 S4 Y - - - - Schedule restoration Y - - - - - Schedule On condition N Y Y - - - - - Schedule On condition N N Y Y - - - - - Schedule On condition N N Y N N Y - - - Schedule discard Legends : Y= Yes N= No F= Failure FF= Functional failure O= Operational consequences N =Non Operational consequences H1/S1/O1/N1 On condition Task H2/S2/O2/N2 Scheduled restoration Task FM= Failure Mode H= Hidden failure consequences S= safety consequences E= Environmental consequences H3/S3/O3/N3 Discard Task H4= Default action H5= Default action S4= Default action Step # 3 Selecting RCM Strategy In process of paint booth, unscheduled breakdown of critical components like fans can cause production and other consequential losses. One of the selected critical components is fans, in which buff deposit may cause other defects like wear, imbalance, etc. Its managed airflow enables to get maximum efficiency of the paint sprayed while directing overspray away from the painted finish. Predictive maintenance through vibration monitoring is selected to keep the function preserved. The parameter of velocity is selected to monitor such that must it be evenly maintained and balanced at 0.5mm/sec to perform proper function. 24
  • International Journal of Industrial Engineering Research and Development (IJIERD), ISSN 0976 – 6979(Print), ISSN 0976 – 6987(Online), Volume 5, Issue 1, January - February (2014), © IAEME PLANT SURVEY PAINT BOOTH SELECTED FANS SELECTED AS CRITICAL NO SELECT PREVENTIVE MAINTENANCE YES SELECT PREDICTIVE MAINTENANCE VIBRATION MONITORING SELECTED ACCEPTABLE LIMIT 0.5 mm/sec COLLECT DATA CONDITION ANALYSIS & ROOT CAUSE FINDING TREND ANALYSIS OF FAULT DETECTION REMEDIAL ACTION Fig 8: Flowchart for Implementation of Predictive Maintenance 25
  • International Journal of Industrial Engineering Research and Development (IJIERD), ISSN 0976 – 6979(Print), ISSN 0976 – 6987(Online), Volume 5, Issue 1, January - February (2014), © IAEME The data collected (Table 6 and Fig 9) is plotted in given below graph, and analysis performed on these reading revealed operation at alarm level. S.no 1 2 3 4 5 6 7 8 9 10 Table 6: Vibration readings before repair Date Amplitude Unit Alarm Level 15-Oct-11 16-Oct-11 17-Oct-11 18-Oct-11 19-Oct-11 20-Oct-11 21-Oct-11 22-Oct-11 23-Oct-11 24-Oct-11 0.435 0.57 0.56 0.55 0.59 0.43 0.55 0.58 0.61 0.54 m/sec m/sec m/sec m/sec m/sec m/sec m/sec m/sec m/sec m/sec 0.55 0.55 0.55 0.55 0.55 0.55 0.55 0.55 0.55 0.55 TREND DATA 0.7 0.6 0.5 0.4 0.3 TREND DATA 0.2 0.1 0 Fig 9: Equipment Vibration Monitoring Trend report before repair After trend analysis for default detection, it is found that; • • • • buff deposits on fan blades, unbalancing, bearings in deteriorated condition and, oil condition has to be inspected, So for, the remedial action of cleaning has been performed to remove buff deposits from blades and deteriorated bearings were replaced. Fan was then rotated and found 26
  • International Journal of Industrial Engineering Research and Development (IJIERD), ISSN 0976 – 6979(Print), ISSN 0976 – 6987(Online), Volume 5, Issue 1, January - February (2014), © IAEME dynamic unbalanced, so in-situ balancing performed to restore proper functioning. It is dynamically balanced at 1460 rpm and the vibration level reduced from 0.61 mm/sec to 0.5 mm/sec, as shown in graph (Table 7 and Fig 10) below. S.no 1 2 3 4 5 6 7 8 9 10 Table 7: Vibration readings after repair Date Amplitude Unit 25-Oct-11 0.5 m/sec 26-Oct-11 0.51 m/sec 27-Oct-11 0.49 m/sec 28-Oct-11 0.5 m/sec 29-Oct-11 0.52 m/sec 30-Oct-11 0.44 m/sec 31-Oct-11 0.46 m/sec 1-Nov-11 0.5 m/sec 2-Nov-11 0.5 m/sec 3-Nov-11 0.49 m/sec Alarm Level 0.55 0.55 0.55 0.55 0.55 0.55 0.55 0.55 0.55 0.55 TREND DATA 0.54 0.52 0.5 0.48 0.46 TREND DATA 0.44 0.42 0.4 Fig 10: Equipment Vibration Monitoring Trend report after repair In this way, vibration monitoring data provided very detailed assessment of fault causes, and selected repair action performed as per need of equipment condition. Since then, the fans are running smoothly and uninterruptedly. CONCLUSIONS AND PERSPECTIVES The paper highlights application of predictive maintenance strategy and the benefits of its implementation for the equipment at ABC Automobile Company, instead of preventive maintenance. This study focuses on rotating equipment (e.g. motors, pumps, conveyors, compressors), where vibration monitoring can be implemented through RCM. 27
  • International Journal of Industrial Engineering Research and Development (IJIERD), ISSN 0976 – 6979(Print), ISSN 0976 – 6987(Online), Volume 5, Issue 1, January - February (2014), © IAEME The comprehensive literature review is presented of maintenance, its types and the interfacing topics. The qualitative data is collected and analyzed with determining the effectiveness of existing maintenance strategy. Predictive maintenance is proposed in addition to preventive maintenance, and its previewed benefits compared. To preserve function of equipment, RCM seven question analyses performed in test case and vibration monitoring data is collected for fan of paint booth. That data trend is analyzed and used to identify causes of imminent damage. So, equipment is repaired before failure and reliability is increased by eliminating root causes. In this way, RCM helps to plan scheduled maintenance and scarce economic resources on critical equipment having high risk of failure. The paper reveals that the ABC Automobile Company Ltd can achieve enhanced manufacturing performance leading to competitive advantage with successful RCM implementation through predictive maintenance. Due to limited resources and time, the paper showed only test case of fan of paint booth, but in case it will implemented on all critical equipment then it will further clarify the differences and benefits of predictive maintenance strategy over other. So, it is strongly recommended to implement this proposal and analyze the situation differences to explore effective Reliability Centered Maintenance. REFERENCES 1. Abdul Raouf S.I., (2004) "Productivity enhancement using safety and maintenance integration: An overview", Kybernetes, Vol. 33 Iss: 7, pp.1116 - 1126. 2. Alireza Ahmadi, Peter Söderholm, Uday Kumar, (2010) "On aircraft scheduled maintenance program development", Journal of Quality in Maintenance Engineering, Vol. 16 Iss: 3, pp.229 – 255. 3. Amik Garg, S.G. Deshmukh, (2006) "Maintenance management: literature review and directions", Journal of Quality in Maintenance Engineering, Vol. 12 Iss: 3, pp.205 – 238. 4. Bhadury, B. (1988), Total Productive Maintenance, Allied Publishers Limited, New Delhi. 5. Brook, R. (1998), "Total predictive maintenance cuts plant costs", Plant Engineering, Vol. 52 No.4, pp.93-5. 6. Dekker, R. (1996), "Applications of maintenance optimization models: a review and analysis", Reliability Engineering and System Safety, Vol. 51 pp.229-40. 7. Gits, C. (1992), "Design of maintenance concepts", International Journal of Production Economics, Vol. 24, No.3, pp.217-26. 8. Hannan, R., Keyport, D. (1991), "Automating a maintenance work control system", Plant Engineering, Vol. 45 No.6, pp.108-10. 9. Herbaty, F. (1990), Handbook of Maintenance Management: Cost Effective Practices, 2nd ed., Noyes Publications, Park Ridge, NJ. 10. Higgins, L.R., Brautigam, D.P., Mobley, R.K. (1995), Maintenance Engineering Handbook, 5th ed., McGraw-Hill Inc., New York, NY. 11. Inês Flores-Colen, Jorge Manuel Caliço Lopes de Brito, Vasco Peixoto de Freitas(2011), “On-site performance assessment of rendering façades for predictive maintenance”, Structural Survey, Volume: 29, Issue: 2 2011. 12. J.M. Simões, C.F. Gomes, M.M. Yasin, (2011) "A literature review of maintenance performance measurement: A conceptual framework and directions for future research", Journal of Quality in Maintenance Engineering, Vol. 17 Iss: 2, pp. 116 – 137. 28
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