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  1. MAINTENANCE ENGINEERING Engr. Muhammad Sajid Lecturer Department of Chemical Engineering
  2. • MAINTENANCE • SAFETY Note: Some data/images in this presentation is takes from different books and internet and is only used for educational purposes. Credit goes to original authors only.
  3. MAINTENANCE ENGINEERING MAINTENANCE  The act of maintaining or the state of being maintained.  The work of keeping something in proper condition; upkeep.  care or upkeep, as of machinery or property: With proper mai ntenance the carWILL last for many years.  Any activity – such as tests, measurements, replacements, adjustments and repairs — intended to retain or restore a functional unit in or to a specified state in which the unit can perform its required functions.  For material — all action taken to retain material in a serviceable condition or to restore it to serviceability. It includes inspection, testing, servicing, classification as to serviceability, repair, rebuilding, and reclamation.
  4. MAINTENANCE ENGINEERING (Cont.)  All actions necessary for retaining an item, or restoring to it, a serviceable condition, include servicing, repair, modification, overhaul, inspection and condition verification  Increase availability of a system  Keep system’s equipment in working order  Maintenance is a set of organised activities that are carried out in order to keep an item in its best operational condition with minimum cost acquired.
  5. PURPOSE OF MAINTENANCE  To keep equipment/system operative.  Attempt to maximize performance of production equipment efficiently and regularly  Prevent breakdown or failures  Minimize production loss from failures  Increase reliability of the operating systems  To keep operation safe  To prevent leakages/losses
  6. OBJECTIVES IN MAINTENANCE  To achieve product quality and customer satisfaction through adjusted and serviced equipment  Maximize useful life of equipment  Keep equipment safe and prevent safety hazards  Minimize frequency and severity of interruptions  Maximize production capacity – through high utilization of facility
  7. PROBLEMS IN MAINTENANCE  Lack of management attention to maintenance  Little participation by accounting in analyzing and reporting costs  Difficulties in applying quantitative analysis  Difficulties in obtaining time and cost estimates for maintenance works  Difficulties in measuring performance  Production load  Continuous operation  Unskilled staff
  8. CAUSES OF PROBLEMS IN MAINTENANCE  Failure to develop written objectives and policy  Inadequate budgetary control  Inadequate control procedures for work order, service requests etc.  Infrequent use of standards  To control maintenance work  Absence of cost reports to aid maintenance planning and control system  Unavailability of spares
  9. MAINTENANCE OBJECTIVES  Must be consistent with the goals of production (cost, quality, delivery, safety)  Must be comprehensive and include specific responsibilities
  10. Maintenance Objectives PLANT M A I N T E N A N C E Reduce Breakdowns Reduce Downtime Improving Equipment Efficiency Improving Inventory Control Implementing Cost Reduction Maximising Production Optimising Resources Utilisation Optimising Useful Life of Equipment Minimising Energy Usage Providing Budgetary Control Figure 2.3 Maintenance Objectives
  11. MAINTENANCE COSTS  Cost to replace or repair  Labor/Labour cost  Losses of output  Delayed shipment  Scrap and rework  Safety measurements
  12. Question?  Why do we need maintenance?  What are the costs of doing maintenance?  What are the costs of not doing maintenance?  What are the benefits of maintenance?  How can maintenance increase profitability of company?
  13. MRO MAINTENANCE, REPAIR & OVERHAUL/OPERATIONS (MRO) All actions which have the objective of retaining or restoring an item in or to a state in which it can perform its REQUIRED FUNCTION. The actions include the combination of all technical and corresponding administrative, managerial, and supervision actions."
  14. TYPES OF MAINTENANCE  Generally maintenance is classified into four categories:  Preventive maintenance  Corrective or Breakdown maintenance  Scheduled maintenance  Predictive (Condition-based) maintenance (some authors prefer three categories- scheduled and preventive maintenances are merged)
  15. TYPES OF MAINTENANCE (Cont.) There are also some other types of maintenance; i.e.  Operational Maintenance  Reliability Centered Maintenance  Improvement Maintenance (IM)
  17. PREVENTIVE MAINTENANCE  Principle – “Prevention is better than cure”  Procedure - Stitch-in-time  Preventive maintenance is maintenance performed in an attempt to avoid failures, unnecessary production loss and safety violations. where equipment is maintained before break down occurs. This type of maintenance has many different variations and is subject of various researches to determine best and most efficient way to maintain equipment. Recent studies have shown that Preventive maintenance is effective in preventing age related failures of the equipment. For random failure patterns which amount to 80% of the failure patterns, condition monitoring proves to be effective.  It ◦ Locates weak spots of machinery and equipments ◦ Provides them periodic/scheduled inspections and minor repairs to reduce the danger of unanticipated breakdowns
  18. ADVANTAGES OF PM  Reduces break down and thereby down time  Less odd-time repair and reduces over time of crews  Greater safety of workers  Lower maintenance and repair costs  Less stand-by equipments and spare parts  Better product quality and fewer reworks and scraps  Increases plant life  Increases chances to get production incentive bonus
  19. CORRECTIVE or BREAKDOWN MAINTENANCE  Corrective or Breakdown maintenance implies that repairs are made after the equipment is failed and can not perform its normal function anymore  Corrective maintenance can be defined as the maintenance which is required when an item has failed or worn out, to bring it back to working order. Corrective maintenance is carried out on all items where the consequences of failure or wearing out are not significant and the cost of this maintenance is much greater than PREVENTIVE MAINTENANCE.
  20. CORRECTIVE or BREAKDOWN MAINTENANCE (Cont.)  Quite justified in small factories where: ◦ Down times are non-critical and repair costs are less than other type of maintenance ◦ Financial justification for scheduling are not felt
  21. DISADVANTAGES OF CORRECTIVE MAINTENANCE  Breakdown generally occurs inappropriate times leading to poor and hurried maintenance  Excessive delay in production & reduces output  Faster plant deterioration  Increases chances of accidents and less safety for both workers and machines  More spoilt materials  Direct loss of profit  Can not be employed for equipments regulated by statutory provisions e.g. cranes, lift and hoists etc
  22. SCHEDULED MAINTENANCE  Scheduled maintenance is a stitch-in-time procedure and incorporates ◦ inspection ◦ lubrication ◦ repair and overhaul of equipments  If neglected can result in breakdown  Generally followed for: ◦ overhauling of machines ◦ changing of heavy equipment oils ◦ cleaning of water and other tanks etc.
  23. PREDICTIVE (CONDITION-BASED) MAINTENANCE  In predictive maintenance, machinery conditions are periodically monitored and this enables the maintenance crews to take timely actions, such as machine adjustment, repair or overhaul  It makes use of human sense and other sensitive instruments, such as ◦ audio gauge, vibration analyzer, amplitude meter, pressure, temperature and resistance strain gauges etc.
  24. PREDICTIVE MAINTENANCE (CONTD.)  Unusual sounds coming out of a rotating equipment predicts a trouble  An excessively hot electric cable predicts a trouble  Simple hand touch can point out many unusual equipment conditions and thus predicts a trouble
  25. MAINTENANCE COSTS Maintenance Commitment Cost Breakdown Cost
  26. MAINTENANCE COSTS Maintenance Commitment Cost PM Cost Breakdown Cost
  27. MAINTENANCE COSTS Maintenance Commitment Cost PM Cost Breakdown Cost Total Maintenance Cost
  28. MAINTENANCE COSTS Maintenance Commitment Cost PM Cost Total Maintenance Cost Breakdown Cost Optimal
  29. OPERATIONAL MAINTENANCE  Where equipment is maintained in OPERATING CONDITION.  Operational maintenance is the program focused on the regular task that will maintain all the critical machinery and the system in optimum operating conditions. The major objectives of the program are to 1.Eliminating breakdown 2.Eliminating deviation 3.Eliminating unnecessary repairs 4.Optimize all the critical planned system
  30. RELIABILITY CENTERED MAINTENANCE  It is a process to ensure that assets continue to do what their users require in their present operating context.  It is generally used to achieve improvements in fields such as the establishment of safe minimum levels of maintenance, changes to operating procedures and strategies and the establishment of capital maintenance regimes and plans. Successful implementation of RCM will lead to increase in cost effectiveness, machine uptime, and a greater understanding of the level of risk that the organization is managing.
  31. RELIABILITY CENTERED MAINTENANCE (Cont.)  It regards maintenance as the means to maintain the functions a user may require of machinery in a defined operating context.As a discipline it enables machinery stakeholders to monitor, assess, predict and generally understand the working of their physical assets.This is embodied in the initial part of the RCM process which is to identify the operating context of the machinery, and write a Failure Mode Effects and Criticality Analysis (FMECA).The second part of the analysis is to apply the "RCM logic", which helps determine the appropriate maintenance tasks for the identified failure modes in the FMECA.
  32. DETERMININGTHE SIZE OF REPAIR CREWS  Problem:  A factory has 200 machines and the maintenance engineer supervises the repair crews who repair malfunctioning machines. The maintenance policy is to repair the broken down machine and bring back in production within 2 hours on the average. If average breakdown rate is 3.5 machines/hour and each repair crew can repair 0.25 machine per hour on the average. How many repair crews are required ?
  33. SOLUTION The formula for average repair rate () is 1 ts = ---------- or  =  + 1/ ts  -  Where  = repair rate  = arrival rate of malfunctioning machines ts = average time arrivals in the system Required average repair rate  = 3.5 + 1 / 2 = 4 machines / hour No. of Crews =   machines/hour a crew can repair = 4  0.25 = 16 repair crews required