Total Productive Maintenance
Strategos, Inc.3916 WyandotteKansas City MO 64111 USA816-931-1414Total Productive MaintenanceTPMByQuarterman Lee, P.E.Strategos, Inc.06 January 2009C O N S U L T A N T SE N G I N E E R SS T R A T E G I S T Swww.strategosinc.com1 2009 Strategos, Inc.
Total Productive MaintenanceQuarterman Lee26 July 2008IntroductionTotal Productive Maintenance (TPM) is the maintenance sub-system of LeanManufacturing. TPM improves manufacturing performance by reducing cost, improvingquality and increasing productivity.As with other parts of Lean, TPM borrows tools and techniques from other disciplines aswell as previously developed and proven maintenance techniques. The combination,integrated as a system and further integrated with the larger Lean system, producesresults far beyond the individual techniques; i.e., the system is more than the sum of itsparts.Losses & Cost AvoidanceIn one sense, everything in maintenance is waste since none of it directly contributes tothe customer's needs andwants. While a perfectfactory with perfectequipment would need zeromaintenance effort, realfactories and realequipment needmaintenance to function.Without it, they createfurther waste in lost timeand defects. The objectiveof TPM is to minimize thetotal waste or, in TPMterms, loss.Figure 1 Maintenance LossesC o s t( )Optimizing MaintenanceMaintenance-related losses come in many forms.Accounting systems show some costs (losses) butothers remain hidden as in figure 1. For example,the exact cost of maintenance labor and parts is easyto track. The cost of a defective part is somewhateasy to track but the "commotion cost" of the defectis nearly impossible to track and usually muchgreater. For an example, see: The True Cost ofDefective Quality.HiddenCostTotalCostVisibleCostMaintenance EffortFigure 2 Optimizing Maintenance Cost2 2009 Strategos, Inc.
The trick is to find the balance between direct maintenance expenditures and the hiddencosts while ensuring that maintenance resources are effectively used. Analytically andquantitatively, this is very difficult. From this author's experience and observation,however, few (if any) factories spend too much on maintenance. Most operate far to theleft on the total Cost Curve of figure 2. Well-managed maintenance is nearly always agood investment.The Origins of TPMThe demands for predictable machine performance in Lean Manufacturing led to thedevelopment of TPM. Early on, the people at Toyota must have realized that manyquality problems and setup problems originated in poor maintenance. Total QualityTechniques, Statistical Process Control (SPC) and problem solving teams transferred wellto maintenance issues. Reliability Centered Maintenance (RCM) also contributed.Reliability Centered Maintenance developed from the military's development ofReliability theory that, in turn, came from statistical theory. Statistical theory alsocontributed to the development of SPC. The use of problem solving teams came fromEric Trist's Socio-Technical Systems as well as from Reg Revans' Action Learning.Figure 3 illustrates this simplified summary of TPM's intenance (RCM)Total heorySocio-TechnicalSystemsStatistical ProcessControl (SPC)Total Quality (TQM)Six SigmaTeamDevelopmentFigure 3 The Origins of TPMResultsSome years ago I was Maintenance Superintendant in a large, 100-year-old steel foundry.We employed most of the principles, tools and techniques of TPM long before they hadnames. The results were excellent. For example, our average downtime on overheadcranes went from about 17% to 2.5%. Other major equipment showed comparableresults. Here are some other results reported by industry: MRC Bearings reduced unplanned downtime by 98% in one cell and 99% inanother - all within one year. Monsanto runs their three-year old TPM start-up plant at 97% on-stream timewhile most other units run between 85% and 90%. 3M reduced their maintenance cost by 60% within three years. DuPont reduced off-quality by 69% and improved capacity by 29% in three years.3 2009 Strategos, Inc.
Harley-Davidson estimates that the ROI from TPM has been ten-fold to the costof implementation. Kodak reported a 5 million investment in TPM that resulted in a 16 millionincrease in profits.Reliability & Reliability Centered MaintenanceBeginning in World War II, the WarDepartment sponsored a new sciencecalled Reliability. Reliability is thescience of maintenance. It uses statisticsand failure theory to measure,understand and improve the performanceof equipment and maintenance.Reliability theory can guide engineers asthey design and test new equipment.After equipment has been in service,reliability data tells the maintenanceengineer how to improve itsperformance.As the Gulf Wars demonstrated, thisscience has produced outstanding resultsin defense. Regrettably, little of thisknowledge has found its way intoindustry. Most maintenance operationsstill operate on the principal of "if it ain'tbroke, don't fix it".Mission ReliabilityFigure 4 Mission ReliabilityQuestion: If we dispatch 1000 heavybombers for an 8-hour mission, whatpercentage will complete the missionwithout mechanical failure?Reliability MetricsReliability uses many metrics for evaluating equipment and systems. The original metric,Mission Reliability, answered the question of figure 4. For industrial maintenance, themetric of Failure Rate is usually more relevant. Failure rate is the number of failures per1000 hours of operation. It can apply to a complex system such as a machine tool or itcan apply to a large number of simple components such as light bulbs. For this discussionfocuses on individual units of complex equipment.Failure ModesFailures occur in one of several modes. Understanding modes and what mode is the likelycause for specific failures is important because different approaches or strategies may bemore or less effective on the various modes. Table 1 summarizes the various failuremodes and illustrates their characteristic failure rates over time.4 2009 Strategos, Inc.
Table 1 Failure Modes & CharacteristicsFailure ModeFailure RateMinor WearoutComplex equipment requiresreplacement of components as eachcomponent reaches its individualwearout life. Since components havedifferent lives and are changed atdifferent times, the failure rate tendsto be relatively constant and mimicsthe random failure rate curve.F a ilu r e s /1 0 0 010,00020,00030,00040,00050,000Cumulative Operating HoursF a ilu r e s /1 0 0 0H o u rsFailure RateRandom Failures010,00020,00030,00040,00050,000Cumulative Operating HoursFailure RateH o u rsThis occurs when major sub-systemsor structures become worn orweakened to the point that properrepair is impossible or impractical.Failure rate begins to rise sharply andthe only solution is major overhaul orreplacement.0F a ilu r e s /1 0 0 0Major WearoutEarly Life FailuresMajor Wearout Failures010,00020,00030,00040,00050,000Cumulative Operating HoursFailure RateH o u rsRandom Failures result from variations in both theload imposed on any givencomponent and the variations instrengths of supposedly identicalcomponents. Random failure ratesare essentially constant over the lifeof the equipment, normally small andovershadowed in most practicalcases by other failure modes.H o u rsThese occur when equipment isplaced in service. Causes are substandard components and/orimproper installation. Early life failuresoccur frequently when the equipmentis first placed in service and thenrapidly decline.F a ilu r e s / 1 0 0 0Early LifeFailure Rate CurveMinor Wearout Failures010,00020,00030,00040,00050,000Cumulative Operating HoursWhen the previous failure modes arecombined, the result is the "BathtubCurve", familiar to many.F a ilu r e s / 1 0 0 0Early Life, Random &WearoutH o u rsFailure RateCombined Failure Rate010,00020,00030,000Cumulative Operating Hours5 2009 Strategos, Inc.40,00050,000
Design DeficiencyH o u rsFailure RateThe worst problems will normally becorrected early on until the failure rateis reduced to a tolerable level. At thatpoint, remaining design deficienciesare indistinguishable from minorwearout 0Cumulative Operating HoursH o u rsFailure RateCombined Failure Rate- All ModesF a ilu r e s / 1 0 0 0All Modes CombinedWith all modes combined, the failurecurve is the familiar bathtub but withspikes of increased failures atirregular time. Determining the modefor specific failures requires additionalinvestigation and cannot bedetermined from the failure curvealone.Design Deficiency Failure RateF a ilu r e s / 1 0 0 0This type of failure is the result ofdesign error and shows up as aseries of wearout failures. This type offailure does not occur on equipmentthat has been extensively tested anddeveloped. It is inevitable on newdesigns that have not beenthoroughly tested and on the "special"machines that are often used inindustry.010,00020,00030,000Cumulative Operating HoursEquipment Reliability MetricsMetrics help to focus efforts on the most critical equipment rather than reacting to thecrisis de jour. They measure progress and help to adjust efforts accordingly. They arecritical for identifying and resolving specific problems. Equipment metrics can besurprisingly simple. Only three data elements, collected for each machine and analyzedproperly, are really necessary for most situations.This discussion is about the metrics for machine performance. It does not include metricsof maintenance department productivity, budgeting or cost allocation. Such additionalmetrics are required to operate a maintenance department effectively.All these metrics are most effective in graphical form. They are not very meaningful asindividual numbers. However, in the context of past and future, trends, anomalies andpatterns reveal themselves.All of the first four metrics, the most useful, derive from three numbers. Assuming acalculation period of one week, the following questions must be answered: How many breakdowns (failures) did we have this week? How long did each breakdown take to repair? How many hours were scheduled for the equipment?6 2009 Strategos, Inc.
Calculations and tracking can be further simplified by assuming that each machine isscheduled for about the same production (say 40 or 80 hours) and simply using one weekas the time bucket.Table 2 Equipment EffectivenessSymbol(Lambda)DescriptionFailure rate is one of the simplest and mostuseful metrics for machine performance. Using aweek, month or other convenient period in placeof actual operating hours can approximate it. Ifdata is accumulated on a (say) weekly basis, theonly input is the number of breakdowns duringthat week.MTBFMTBF is also a metric for machine performance.It is the inverse of Failure Rate and is thuscalculated from the same parameters. It is ameaningful metric for long periods of time butnot suitable for daily or weekly monitoring. Ifthere are no breakdowns in a given period, theMTBF for that period is mathematically"undefined."MTTRMean-Time-To-Repair is another simple yetvaluable metric for industrial maintenance. Itreflects both the severity of breakdowns and theefficacy of repair activities.AAvailability is the portion or percentage of timethat equipment is available for operation. It iscommonly referred to as “Uptime”. Availability isanother useful metric for industrial maintenanceand you will want to track it along with FailureRate and MTTR. Availability derives from thesame data collected for MTTR and Failure Rate.It is easy to calculate.R(T)Reliability is the probability that equipment willcomplete a mission of length “t” without failure. Itis an exponential function. Reliability has limiteduse for most industrial maintenance although itis important for military and other applications.OEEOverall-Equipment-Effectiveness is a new metricthat has received considerable publicity in recentyears. It attempts to capture all the parametersin a single measure. However, the practicalapplication is somewhat limited.7 2009 Strategos, Inc.Formula
Maintenance StrategiesSeveral strategies or approaches are available for improving the maintenance orbreakdown performance of equipment. These are: Breakdown, IRAN (Inspect & RepairAs Necessary), Predictive and Redesign. Table 3 summarizes these strategies.Table 3 Maintenance StrategiesEarly LifeXXRandomX XXMinor WearoutXXMajor WearoutX X XDesign DeficiencyXTable 4 Strategies & Failure Modes8 2009 Strategos, Inc.RedesignPredictiveIRANTable 4 shows which strategies usually apply to eachfailure mode.MaintenanceStrategiesBreakdownThe best strategy for a particular machine or situationdepends, partly, on the failure mode being experienced. Forexample, IRAN is seldom effective for preventing early lifefailures. These rarely give warning and there is no historyto draw upon. Early life failures must be addressed in theoriginal design and also in the original manufacture andtest of the equipment. Once in service, about all you can dois wait until something breaks. This is why one of the"Pillars of TPM" is new equipment management.X
Note that the redesign (design) strategy applies to all failure modes. Throughout theequipment life, proper design and then redesign as required is the most critical elementfor ensuring equipment performance. Yet capital equipment is often purchased usingprice as the primary decision factor.Pillars of TPMTotal Productive Maintenance is often presented as a series of pillars supporting LeanManufacturing and resting on a foundation of education and training. Below this is theattitude of environmental responsibility and safety. Figure 5 illustrates. Thisrepresentation is adequate as a starting point. However, TPM, like Lean itself, is adynamical system and cannot be fully understood with a static model.Figure 4 The Pillars of TPMSupporting LeanMaintenance enables and supportsLean efforts in at least three majorways: Quality, Setup Reduction(SMED) and predictability. In turn,other Lean elements support TPMthrough Workcells, Teamwork andProblem-solving.T P MO ffic eQ u a lit yP ro c e s sE q u ip m e n tN e wE q u ip m e n t Im p ro v e m e n tM a in te n a n c eP la n n e dA u to n o m o u sM a in te n a n c eLean ManufacturingEducation & TrainingSafety/EnvironmentThe FoundationsEducation & Training—Education, training and investments in people characterize allaspects of Lean. In the maintenance area, they are even more important because of thespecialized knowledge required on typical manufacturing equipment. This is one of thefoundation stones of TPM. Without it, the pillars of TPM will have limited impact.Safety/Environment— Underlying even the training and education piece are the morefundamental values of responsibility to the environment and safety for employees. Oneimportant reason is simple: it is the right thing to do.A more pragmatic reason involves motivation. Most people want to be a part ofsomething larger than themselves; appeals to higher motivation bring involvement andcommitment. It is difficult to argue against safety and a common commitment to safetycan be a bond that brings people together on other issues.Autonomous MaintenanceAutonomous maintenance is the concept that the people who operate a machine shouldmaintain the machine. The degree of autonomous maintenance depends on the level oftraining and the abilities of operators. It often starts with basic lubrication, cleaning andinspection and then graduates to minor or even major repairs.9 2009 Strategos, Inc.
For example, in the foundry where this author worked, machinists repaired andoverhauled their own machine tools. A trained and competent machinist is certainlycapable of overhauling a gearbox. And, as the users, they tended to know the equipmentintimately. In the military, everyone cleans their own weapon. When their life depends onproper functioning, people take more care.Autonomous maintenance frees resources in the maintenance department for the otheractivities such as equipment improvement or major overhauls. It amplifies themaintenance efforts and involves the operators who then take better care of theequipment.Planned MaintenanceFigure 5 Planned & Unplanned MaintenancePlanned maintenance is the deliberate planning andscheduling of maintenance activities as opposed toreacting to breakdowns and emergencies. A maintenancedepartment that uses TPM effectively generally devotesless than 10% of its labor hours to such unplannedactivities. Without TPM it is not unusual for 80%-90% ofthe labor to be unplanned.Unplanned maintenance is a strong indicator thatprevention and improvement programs are non-existentor ineffective. In addition, high percentages of unplannedmaintenance creates, among others, the followingproblems: Huge inefficiencies in maintenance labor. Confusion and disturbance in scheduling,production and other areas. Morale problems.Without TPMPlanned15%Unplanned85%Unplanned10%With TPMPlanned90%Equipment ImprovementImproving equipment constantly is a major part of TPM. This author witnessed anoutstanding example of this some years ago at Toyota's Kamigo Engine plant. Toyotawas using the same type of American equipment that I had seen at Ford Motor Companyyears earlier. However, Toyota's equipment was so reliable that it ran with far fewerpeople and far better quality. For more on this see Kamigo engine Plant, 1985.Most production equipment has not had the extensive design, testing and developmentcommon in mass-produced products such as automobiles. Accordingly, there are manydeficiencies that may not be evident when the equipment first goes into service. Inaddition, each manufacturing plant and its products tends to be different and can benefitby design changes that adapt the machines better to their individual situations.Older equipment does not necessarily have to be replaced. In many cases, it can beupgraded, overhauled and made better than new. In our steel foundry, we did this with10 2009 Strategos, Inc.
fourteen of our overhead cranes. Some were upgradedand re-rated for heavier capacity. All were fitted withnew controls, structural deficiencies were fixed andthe cranes made better than new. Several of thesecranes were over 45 years old.Figure 6 Steel Foundry CraneNew Equipment ManagementNew equipment management is related somewhat to equipment improvement. It refers tothe careful design, selection and testing of equipment. The purpose is to ensure a smoothcommissioning process with minimal design defects and problems.New equipment management includes vendor selection, evaluating options formaintainability, training personnel in advance and other common-sense techniques.Process Quality ManagementIn TPM making the equipment run is only part of Maintenance's job. Ensuring that theequipment is capable of producing parts well within the tolerance range, processcapability, is also a primary responsibility.Worn bearings and ways, undo vibration, bent shafts and multiple other maintenanceproblems contribute to the gradual deterioration of process capability. With constant use,machines still run but become "finicky." For example, a particular machine shop lathethat the author recalls could only be run by a particular operator. He was the only onewho knew exactly where the ways were worn and how to compensate.Office TPMTPM also attempts to carry these principles into the office. This might be stretching theconcept a little too far as other paradigms are likely to be more applicable.TPM In A NutshellLike much in Lean, TPM is a simple yet complex and subtle thing. This is partly becauseof the dynamic effects within TPM and interactions with other lean elements. In thisarticle, we have only touched on a few basics. Our graphic summary, “TPM In ANutshell” attempts to depict TPM in various aspects
Total Productive Maintenance (TPM) is the maintenance sub-system of Lean Manufacturing. TPM improves manufacturing performance by reducing cost, improving quality and increasing productivity. As with other parts of Lean, TPM borrows tools and techniques from other disciplines as well as previously developed and proven maintenance techniques.
1 Total Productive Maintenance (TPM) The Total Productive Maintenance is a set of methods and procedures adopted in a company as support of the production system in the logic of just-in-time and total quality control. 1.1 The evolution of the maintenance management Until the '50s, the maintenance concept was to fix items when they are broken.
What is Total Productive Maintenance (TPM)? It can be considered as the medical science of machines. Total Productive Maintenance (TPM) is a maintenance program, which involves a newly defined concept for maintaining plants and equipment. The goal of the TPM program is to markedly increase production while, at the same time, increasing employee
What is Total Productive Maintenance ( TPM ) ? It can be considered as the medical science of machines. Total Productive Maintenance (TPM) is a maintenance program which involves a newly defined concept for maintaining plants and equipment. The goal of the TPM program is to markedly increase production while, at the same
Total Productive Maintenance (Total Productive Maintenance) is not only a maintenance strategy, but also a business improvement tool that companies use to remain competitive whilst improving customer¶s satisfaction and reliability. T he purpose of this researc h is to understand the impact of the T PM elements and their performanc e roles .
The concept of Total Productive Maintenance (TPM) has been introduced and developed by Japanese in 1971. This came in response to the maintenance and support problems in commercial factory. It is team-based preventive and productive maintenance and involves every level, from top executive to the floor operator. TPM has been proven to be
Total productive maintenance: literature review and directions I.P.S. Ahuja and J.S. Khamba Punjabi University, Patiala, India Abstract Purpose – The purpose of this paper is to review the literature on Total Productive Maintenance (TPM) and to present an overview of TPM implementation practices adopted by the manufacturing organizations.
in the Total Productive Maintenance (TPM) philosophy [11]. In all this, higher level of production effectiveness is attained in terms of cost effectiveness, safety, employee motivation, product quality, reduced defects rate and market positioning in order fulfillment [10]. III. TOTAL PRODUCTIVE MAINTENANCE (TPM) REVIEW
4 BAB II LANDASAN TEORI . 2.1 Total Productive Maintenance (TPM) Total Productive Maintenance (TPM) merupakan suatu aktivitas perawatan yang mengikut. sertakan semua elemen dari perusahaan, yang bertujuan untuk . menciptakan suasana kritis (critical mass) dalam lingkungan industri guna mencapai zero defect dan zero accident (Kurniawan, 2013).
