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Preventive MaintenancePresented by:Mario HanyAhmed EssamAlaa FaikIhab HassanHany AyadMaintenance Maintenance is a set of organized activities that are carried out in order to keep an item in its best operational condition with minimum cost acquired.the work of keeping something in proper condition; upkeep. This would imply that maintenance should be actions taken to prevent a device or component from failing or to repair normal equipment degradation experienced with the operation of the device to keep it in proper working orderTypes of MaintenanceMaintenance may be classified into four categories:(some authors prefer three categories- scheduled and preventive maintenances are merged)

Corrective or Breakdown maintenancePredictive (Condition-based) maintenanceScheduled maintenancePreventive maintenance

Corrective or Breakdown MaintenanceCorrective or Breakdown maintenance implies that repairs are made after the equipment is failed and can not perform its normal function anymore

Quite justified in small factories where: Down times are non-critical and repair costs are less than other type of maintenanceFinancial justification for scheduling are not felt

Disadvantages of Corrective MaintenanceBreakdown generally occurs inappropriate times leading to poor and hurried maintenanceExcessive delay in production & reduces outputFaster plant deterioration Increases chances of accidents and less safety for both workers and machinesMore spoilt materialsDirect loss of profitCan not be employed for equipment regulated by statutory provisions e.g. cranes, lift and hoists etc

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 asaudio gauge, vibration analyzer, amplitude meter, pressure, temperature and resistance strain gauges etc.Unusual sounds coming out of a rotating equipment predicts a troubleAn excessively hot electric cable predicts a troubleSimple hand touch can point out many unusual equipment conditions and thus predicts a trouble

Scheduled MaintenanceScheduled maintenance is a stitch-in-time procedure and incorporates inspection lubrication repair and overhaul of equipmentIf neglected can result in breakdown Generally followed for: overhauling of machines changing of heavy equipment oils cleaning of water and other tanks etc.

Preventive Maintenance (PM)Principle Prevention is better than cureProcedure - Stitch-in-time It locates weak spots of machinery and equipments provides them periodic/scheduled inspections and minor repairs to reduce the danger of unanticipated breakdowns

What really should PM focus on?Cleaning Found through testing Lubrication and inspectionAnd correcting deficiencies

Predetermined parts replacement should be minimal and done only where statistical evidence clearly indicates wear-out characteristics

9In order for a successful PM system, the system should focus mainly on cleaning, lubrication and correcting deficiencies that are found through testing and inspecting the equipment. Without proper testing and inspection, it would not be possible to decide whether to implement a PM program or when to implement it. For cost reduction purposes and efficiency of the program, its vital to keep the predetermined part replacement to a minimal and done only where statistical evidence clearly points out wear-out characteristics. If the components are not yet in a wear-out stage its best to continue with a PM system to extract the maximum life from it given that the component has an increasing failure rate and the cost of PM is less than corrective control.Maintenance CostsMaintenance CommitmentCostBreakdown Cost10Maintenance CostsMaintenance CommitmentCostPM CostBreakdown Cost11Maintenance CostsMaintenance CommitmentCostPM CostBreakdown CostTotal Maintenance Cost12Maintenance CostsMaintenance CommitmentCostPM CostTotal Maintenance CostBreakdown CostOptimal 13Strategic Importance of Maintenance and ReliabilityFailure has far reaching effects on a firmsOperationReputationProfitabilityDissatisfied customersIdle employeesProfits becoming lossesReduced value of investment in plant and equipment14Maintenance and ReliabilityThe objective of maintenance and reliability is to maintain the capability of the system while controlling costsMaintenance is all activities involved in keeping a systems equipment in working orderReliability is the probability that a machine will function properly for a specified time15Important TacticsReliabilityImproving individual componentsProviding redundancyMaintenanceImplementing or improving preventive maintenanceIncreasing repair capability or speed16Maintenance StrategyEmployee InvolvementInformation sharingSkill trainingReward systemEmployee empowermentMaintenance and Reliability ProceduresClean and lubricateMonitor and adjustMake minor repairKeep computerized recordsResultsReduced inventoryImproved qualityImproved capacityReputation for qualityContinuous improvementReduced variabilityFigure 17.117Failure Classification 1. Persistence failure classifications:Intermittent.Permanent.2.Degree of failure classificationComplete (system).Partial (subsystem).3. Deterioration rate classificationSudden.Gradual.

The Structure of maintenance systemsCentralized maintenance systemDecentralized maintenance systemCombined centralized decentralized maintenance systems.Frequency of breakdownIf the average cost of a breakdown is $1,000, and the cost of preventative maintenance is $1,250 per month, should we use preventive maintenance?ExampleNumber of breakdowns0123Frequency of occurrence.20.30.40.10ExampleExpected cost to repair = 1.4 breakdowns per month X $1000 = $1400 Preventive maintenance = $1250PM results in savings of $150 per monthNumber of BreakdownsFrequency of OccurrenceExpected number of Breakdowns0123.20.30.40.101.000.30.80.301.40Determining the Size of Repair CrewsProblem: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 ?SolutionThe formula for average repair rate () is 1ts = ---------- 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 / hourNo. of Crews = machines/hour a crew can repair= 4 0.25 = 16 repair crews requiredCatastrophic failure

9/4/201524

TheDeep water Horizondrilling rig explosionrefers to the April 20, 2010 explosion.

9/4/20152525Advantages of PMAdvantages: Reduces break down and thereby down time Loss odd-time repair and reduces over time of crewsGreater safety of workersLower maintenance and repair costsLess stand-by equipments and spare partsBetter product quality and fewer reworks and scrapsIncreases plant lifeIncreases chances to get production incentive bonus

SummaryPM is not difficult to achieve.It is an essential part for cost reductionThere is an element of risk involved in PMCareful planning and execution will reduce the risk of PMThe biggest benefits of a PM program occur through painting, lubrication, cleaning and adjusting, and minor component replacement to extend the life of equipment and facilities.

27Briefly tie these concepts together one last timeThank You