Maintainance engineering and management
- 1. BDU-BiT FACULITY OF MECHANICAL AND INDUSTRIAL ENGINEERING INDUSTRIAL ENGINEERING MAINTENANCE ENGINEERING AND MANEGEMENT NAME: Mistire-selassie Taddese ID: 1011282 SUBMITTED TO: Daniel A. Date: 09/07/2013 E.C.
- 2. Assignment-I (15%) Write a brief technical note on the following points. 1. The concept of autonomous maintenance, its characteristics, benefits, and the steps required to implement autonomous maintenance. 2. Overall equipment maintenance (OEE) is the key performance indicator developed to measureequipment/machinery effectiveness.Considering this write a note on the following issues: a. Definition and measurementof OEEdescribing each stages in the analysis b. Taking a specific scientific paper (i.e. from journal articles, unpublished thesis or dissertation papers), demonstrate how OEE is applied to industrial applications comparing to standard settings. N.B. For question #2, you must putthe reference you are considering for your report. 1. Definition of autonomous maintenance Autonomous maintenance is defined as a maintenance strategy where machine operators continuously monitor their equipment, make adjustments and perform minor maintenance tasks on their machines. This is done rather than assigning a dedicated maintenance technician to performmaintenance and regularly scheduled upkeep. Autonomous maintenance is the firstpillar in the TPM strategy. Example: In production plants and engineering operations the following autonomous
- 3. maintenance tasks can be easily carried out by production or processing operations, these are only a few items and each operation is different: 1. Greasing of bearings (care must be taken not to over grease 2. Top up of oil reservoirs (lubricating/hydraulic) for fixed and mobile plant machinery 3. Repair of basic work areas such as benches, chairs, and some tools 4. Condition monitoring of tools and complex machinery such as temperatures, vibration and unusual operating parameters 5. Cleaning of plant items involving isolating plant and disassembling components to perform cleaning Characteristics of autonomous maintenance 1. 0rganized-led activities 2. Use of audits # determine full implementation of each step. # provide feedback on strengths and weaknesses. # clarify what needs to be achieved and best way to do it. 3. Use of activity boards An activity board is a visual tool to guide teams to action. 4. Meeting, one-point lessons and reports Autonomousmaintenance followstwo core principles: 5. To prevent equipment deterioration through proper operation, and; 6. Bringing equipment to, and keeping it at, "like new" status through restoration and proper management. Benefits of autonomous maintenance 1. . It relieves skilled maintenance staff 2. Increasing operator knowledgeof their equipment
- 4. 3. Keeping equipment in a "like new" state, ensuring they are clean and lubricated. 4. The ability to notice emerging issues before they become failures. 5. By allowing machine operators to tackle these routine maintenance inspections and tasks, OEEis further maximized through the reduction of breakdowns and equipment deterioration. The steps required to implement autonomous maintenance Implementing autonomous maintenance may vary slightly depending on each plant's operation, but it's typically broken down into seven steps 1. Increase operator knowledge: This involves training from maintenance technicians on the technical details of how the machine's components work and their purpose, as well as training on problem-solving skills. In short, operators should have four equipment-related skills. These are Detecting abnormalities, Correcting and restoring abnormalities, Setting optimum equipment conditions, Maintaining these optimum equipment conditions. 2. Initial machine cleaning and inspection: Not only is the equipment thoroughly overhauled and cleaned, but the surrounding area is cleaned as well. he goal is to fully restore each piece of equipment to its full performance by identifying and eliminating signs of deterioration. 3. Remove the cause of contamination and improve access: This can be achieved by eliminating all possible sources of contamination and improving accessibility for cleaning and maintenance.
- 5. 4. Develop standards for lubrication and inspection: Standards should indicate which components should be cleaned and lubricated, how they should be cleaned and lubricated, and all other maintenance responsibilities to be assigned. 5. Inspection and monitoring: The operator's maintenance tasks are tracked and compared with the maintenance department's own schedules (usually through a computerized maintenance management system) to ensure the duplication of tasks isn't an issue. 6. Standardize visual maintenance: Standardizing autonomous maintenance and making equipment "visual" is an important step for maintaining the integrity of each piece of machinery. 7. Continuous improvement: Periodically taking the time to step back and dissect standardized processes to see where there is room for improvement is important to ensure you're operating efficiently.
- 6. 2. a) OEE concept OEE is defined as a measureof the total equipment performancethat, in other words, is meant to show the degree to which the equipment is doing what it is supposed to do (Williamson 2006). Itis a tool based on three factors that can be used to analyzeequipment performanceincluding availability efficiency, performanceefficiency and quality efficiency. OEE is used for the identification of production losses that are related to equipment with the purposeof improving the total performanceof the asset. These losses are categorized in aim to providethe foundation for improvementpriorities setting and to help with the initiation of root causeanalysis. The six big losses are measured by the OEE function, which is a multiplication of the availability rate (A), performanceefficiency (P) and quality rate (Q) as shown by the equation: OEE=A*P*Q Availability(A)= 𝑜𝑝𝑒𝑟𝑎𝑡𝑖𝑛𝑔 𝑡𝑖𝑚𝑒 𝑙𝑒𝑎𝑑𝑖𝑛𝑔 𝑡𝑖𝑚𝑒 *100% Operating time= 𝑙𝑒𝑎𝑑𝑖𝑛𝑔 𝑡𝑖𝑚𝑒 − 𝑑𝑜𝑤𝑛𝑡𝑖𝑚𝑒 Performanceefficiency(P)= 𝑡ℎ𝑒𝑜𝑟𝑒𝑡𝑖𝑐𝑎𝑙 𝑐𝑦𝑐𝑙𝑒 𝑡𝑖𝑚𝑒 𝑥 𝑎𝑐𝑡𝑢𝑎𝑙 𝑜𝑢𝑡𝑝𝑢𝑡 𝑐𝑜𝑝𝑒𝑟𝑎𝑡𝑖𝑛𝑔 𝑡𝑖𝑚𝑒 Quality rate(Q)= 𝑡𝑜𝑡𝑎𝑙 𝑝𝑟𝑜𝑑𝑢𝑐𝑡𝑖𝑜𝑛 − 𝑑𝑒𝑓𝑒𝑐𝑡 𝑎𝑚𝑜𝑢𝑛𝑡 𝑡𝑜𝑡𝑎𝑙 𝑝𝑟𝑜𝑑𝑢𝑐𝑡𝑖𝑜𝑛 *100% The OEE measurement tool has its strength in the way it integrates different important aspects of manufacturing into a single measurement tool. The perspectives integrated in the OEE tool are the maintenance effectiveness, production efficiency and quality efficiency as shown in figure
- 7. Steps involved in OEE calculation are: 1.Inputthevalue of total shift time 2.Inputthevalue of planned downtime 3.Calculate the leading time using (total time – planned downtime) 4.Inputthevalue of all downtime and all stop time 5.Calculate the operating time and then availability 6.Inputthevalue of actual cycle time and theoretical cycle time 7.Calculate the operating speed rate= theoretical cycle time/actual cycle time 8.Inputthevalue of actual processing time and total amount produced 9.Calculate net operating rate=actual processing time/operating time 10.Calculate performanceefficiency=net operating rate*operating speed rate Inputthe value of defect amount 11.Calculate quality rate=(total amount produced – defect amount)/total amount produced 12.Finally OEE= Availability*performanceefficiency*quality rate To argue for these series of steps the softwarevisualbasic is used. b) citation: Article in InternationalJournalof Production Research· December 2006 by A. J.DERON J. E. Rooda in Systems Engineering Group, Department of Mechanical Engineering, Eindhoven University of Technology,P.O.Box513. Fromtheir research the OEE is the measureof performanceusing Availability, performanceefficiency and quality rate or in other words availability efficiency=AE, operational efficiency=OE, rate efficiency=RE and quality efficiency=QE. Mathematically OEE=A*P*Q=AE*(OE*RE)*QE AE=(equipment uptime/total time) OE=(production time/equipment uptime) RE=(theoretical production time for actual units/production time) QE=(theoretical production time for effective units/theoretical production time for actual units) So lets see their results fromtheir research using the following table.
- 8. As their observation fromthe machine capacity in different cases case A and B. The difference between the situations is that, incase B, the throughputis larger than incase A so that the productivetime is longer and more items are produced. Because of the longer production time, the downtime is increased and the stand by time decreased as more capacity is required. The results show that RE and QE are the samefor both situations. The differences are expressed by the AE and OE and, as a consequence, the OEE values. As the throughputis increased incase B, the differences between the measurements are not caused by the machine or workstation, butby their environment. The influence of the environment on OEE can be treated more generally by considering the utilization. This measure indicates the portion of the total time that the capacity of the machine is requested. Fromthese two cases A and B as As in caseA OEE=0.474 and in case B OEE=0.592 meaning that in caseA the machine is doing 47.4% of the intended job effectively, on the other hand in case B 59.2% of performanceis fully utilized. THE END