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									 Equipment Efficiency:
Availability, Performance
   and Maintenance
      Operations Analysis and Improvement

                   2010 Fall


                 Dr. Tai-Yue Wang
Industrial and Information Management Department
           National Cheng Kung University


                                                   1/80
              Presentation
      The role of maintenance is to insure the
       survivability and proper functioning of all
       company hardware.
            Most maintenance departments are considered “a
             necessary evil”.
                  Investments required to improve production processes
                   usually take on a low priority.



Dr. Tai-Yue Wang IIM Dept. NCKU                                           2/80
              Presentation
      Maintenance evolution, as well as maintenance
       technique evolution, has developed in parallel for
       many companies.
            Remediate hardware failures.
            Prevent future problems with the equipment.
            Incorporate basic maintenance tasks into their daily
             production routine.
            Predicting equipment breakdowns.

Dr. Tai-Yue Wang IIM Dept. NCKU                                     3/80
              Introduction

          Maintenance’s primary objective is to
           maintain, at a high operative level, the
           productive resources in order to assure their
           service at an expected cost.
          Maintenance is the “machine’s medicine”.
          Determine the right moment to replace the
           equipment.
               It may be better to simply unplug it.
Dr. Tai-Yue Wang IIM Dept. NCKU                            4/80
                                       Introduction
                                  Thinking
                                 revolution
                                                                                            Elements that need maintenance.
                                    The 5S


                                                                                                Machines and tools.
                                  Standard
                 Poka-Yoke                      Jidoka
                                 operations
                                                                Workforce optimization




                                                                                                Facilities (compressed air,
Visual Control




                                                 Multi-


                                                                                                 heating,…)
                                 One-Piece
                      TPM                      functional
                                   flow         workers
                 1                     11 12                 20
                                9
                            7    Leveling          16
                                                                                                 Buildings (walls, illumination,…)
                     Kanban                      SMED
                                Production

                     14                                  5                                   
                     6          JUST IN TIME                4
                     17                                  8                                      Information and transportation
                          18                       15
                 2
                                19 10 13
                                                                3
                                                                                                 systems.


Dr. Tai-Yue Wang IIM Dept. NCKU                                                                                                      5/80
                                       Introduction
                                  Thinking
                                 revolution
                                                                                            Some companies subcontract
                                    The 5S

                                                                                             maintenance.
                                  Standard
                 Poka-Yoke                      Jidoka
                                 operations
                                                                Workforce optimization




                                                                                            Is contemplated in both the
Visual Control




                                                 Multi-
                                 One-Piece
                      TPM                      functional
                                   flow         workers
                 1
                            7
                                9      11 12
                                 Leveling          16
                                                 SMED
                                                             20                              Just-in-time and the 20 keys
                     Kanban     Production

                     14                                  5                                   (key number 9) for lean.
                     6          JUST IN TIME                4
                     17                                  8                                      Improves the availability and
                          18                       15
                 2
                                19 10 13
                                                                3                                performance rates of the
                                                                                                 equipment.

Dr. Tai-Yue Wang IIM Dept. NCKU                                                                                                  6/80
                  Types of maintenance
         Corrective -> All industrial equipment is
          exposed to transitory (wear) or definitive
          breakdowns (catastrophic failure).
               Affecting its functionality and performance.
               Can represent high costs for enterprises.
         Preventive -> The maintenance mission
          cannot only be repairing the breakdowns.
               They should be able to get ahead of the
                breakdowns.
Dr. Tai-Yue Wang IIM Dept. NCKU                                7/80
               Corrective maintenance
                          Also called breakdown maintenance.
                                   Up to the 1950s it was virtually the only
                                    maintenance.
                                        Machine stoppages hardly affected productive time.
                                        Repairs were carried out in an effective way.
  Equipment
performance                                           Substitution




                                             Repair




                                                                     Time

               Time until failure
 Dr. Tai-Yue Wang IIM Dept. NCKU                                                       8/80
                                              Repair time
               Types of corrective maintenance
         Urgent repairs.
            Reestablishing the equipment into service.
            Repair is carried out is temperally.

            The remainder of the tasks will/can be

             scheduled for a future time.



Dr. Tai-Yue Wang IIM Dept. NCKU                           9/80
               Types of corrective maintenance
         Scheduled corrective.
              Appears as a result of urgent repairs.
                   Determine an appropriate time to repair the
                    machine completely.
                   After repairing the damaged component

                           As good as new.
                           At least as it was before.


Dr. Tai-Yue Wang IIM Dept. NCKU                                   10/80
              Repair problems
                  Repair tasks are performed quickly and
                   under pressure, which can cause future
                   problems.
                  Repair time can be very high because
                   replacement part(s) may have to be
                   ordered from a supplier.


Dr. Tai-Yue Wang IIM Dept. NCKU                        11/80
            Repair problems
     Accidents can take place because of poor
      maintenance safety measures.
     Corrective maintenance policy implies higher
      labor costs.
           This policy can be justified in some cases.
                 Equipment with a frequent replacement policy.
                       Like personal office computers.
           When breakdown costs are small.
                                                                  12/80
                  Light bulbs fail.
                IIM
Dr. Tai-Yue Wang Dept. NCKU
                  Types of preventive
                  maintenance
         The preventive maintenance has two variants.
               Systematic preventive maintenance.
               Conditional preventive maintenance or predictive
                maintenance.




Dr. Tai-Yue Wang IIM Dept. NCKU                                13/80
                   Systematic preventive
  Equipment
                   maintenance
performance                                                    Substitution




                                                                                        1960s -> the General
                                                      Repair
                                                                                         Electric Corporation
                  Time until failure
                                                                              Time
                                                                                         systematized a new
                                                       Repair time

                                                                                         type of maintenance
                                                                                         called planned
  Equipment
                                                                                         maintenance.
performance
                                                       Substitution




                                           Intervention duration

                                                                              Time

 Dr. Tai-YueTheoreticalIIM until failure
             Wang time Dept. NCKU                                                                         14/80
                                   Systematic preventive
                                   maintenance
                                                                                            Planned maintenance arrived to
                                                                                             Japan.
  Equipment
performance                                                        Substitution

                                                                                                The bases of this systematic
                                                          Repair                                 preventive maintenance process
                                                                                  Time
                                                                                                 were established.
                    Time until failure

                                                           Repair time

                                                                                                     Systematic substitution of some
                                                                                                      machine components.
  Equipment
performance
                                                           Substitution




                                               Intervention duration



   Dr. Tai-Yue Wang IIM Dept. NCKU
              Theoretical time until failure
                                                                                  Time
                                                                                                                                        15/80
                                   Systematic preventive
                                   maintenance
                                                                                            Applied to general wear or use
                                                                                             components.
  Equipment
performance                                                        Substitution

                                                                                                Know with precision the
                                                          Repair                                 component’s performance
                                                                                  Time
                                                                                                 characteristics.
                    Time until failure

                                                           Repair time




  Equipment
performance
                                                           Substitution




                                               Intervention duration



   Dr. Tai-Yue Wang IIM Dept. NCKU
              Theoretical time until failure
                                                                                  Time
                                                                                                                           16/80
              Systematic preventive
              maintenance
          Replacement policy might call for a
           component to be replaced every week or
           in other ways such as, every 300
           working hours or every 1000 parts
           produced.                Equipment
                                  performance
                                                                                             Substitution




                                                                                 Intervention duration

                                                                                                               Time


Dr. Tai-Yue Wang IIM Dept. NCKU
                                                Theoretical time until failure                              17/80
                      Conditional preventive
                      maintenance
  Equipment
performance
                                                           Substitution


                                                                                    Also called predictive
                                                                                     maintenance.
              Theoretical time until failure
                                               Intervention duration

                                                                          Time      Systematic preventive
                                                                                     maintenance can
                                                                                     become very
  Equipment
                                                                                     expensive.
                                Inspections
performance
                                                           Substitution




                                               Intervention duration

                                                                          Time

 Dr. Tai-Yue Wang time until failureNCKU
           Theoretical IIM Dept.                                                                         18/80
                                   Conditional preventive
                                   maintenance
                                                                                    Conditional preventive
                                                                                     maintenance is used to change
  Equipment
performance
                                                           Substitution
                                                                                     components depending on
                                                                                     their current state.
                                               Intervention duration



              Theoretical time until failure
                                                                          Time
                                                                                        The useful life for costly
                                                                                         components can be extended.

  Equipment
                                                                                    This type of maintenance best
                                Inspections
performance
                                                           Substitution


                                                                                     fits components where
                                               Intervention duration
                                                                                     performance can be
                                                                                                                19/80
   Dr. Tai-Yue Wang IIM Dept. NCKU
              Theoretical time until failure
                                                                          Time

                                                                                     monitored.
                                   Conditional preventive
                                   maintenance
                                                                                    ISO 14000 (environmental
                                                                                     norm) requires that industry
  Equipment
performance
                                                           Substitution

                                                                                     avoid systematic preventive
                                                                                     maintenance when working
                                               Intervention duration



              Theoretical time until failure
                                                                          Time
                                                                                     with environmentally harmful
                                                                                     products.
  Equipment                     Inspections
performance
                                                           Substitution




                                               Intervention duration



   Dr. Tai-Yue Wang IIM Dept. NCKU
              Theoretical time until failure
                                                                          Time
                                                                                                                20/80
                           Conditional preventive
                           maintenance
  Equipment
performance
                                                           Substitution
                                                                                    Predictive maintenance.
                                                                                        Look for correlations between
                                               Intervention duration
                                                                                         multiple parameters and the
              Theoretical time until failure
                                                                          Time
                                                                                         degradation of a component.
                                                                                             Temperature (thermocouples),
                                                                                             Noises (phonometer).
  Equipment                     Inspections
                                                                                             Cracks (X-rays machine).
performance
                                                           Substitution


                                                                                             Pressure losses (manometer).
                                                                                        QS9000 recommends
                                               Intervention duration

                                                                          Time
                                                                                         predictive maintenance.
  Dr. Tai-Yue Wang IIM Dept. NCKU
              Theoretical time until failure                                                                           21/80
               Maintenance program
               implementation
         Almost all machines follow a similar
          lifecycle.
              Hidden small defects.
                     Difficult to detect and to observe -> It does not
                      interfere with functionality.
                           Increase of friction in an axle.
              Apparent small defects.
                     Are more noticeable -> They are normally not
                      repaired.
                           Small vibrations on a machine.
Dr. Tai-Yue Wang IIM Dept. NCKU                                           22/80
              Maintenance program
              implementation
                  Execution under expectations.
                         The defects affect the equipment productivity.
                         the standards of quality will be violated.




Dr. Tai-Yue Wang IIM Dept. NCKU                                            23/80
               Maintenance program
               implementation
         Almost all machines follow a similar lifecycle.
              Intermittent stops.
                     The machine intermittently produces defect parts.
                     Small repairs are performed.
              Stops and breakdowns.
                     Breakdowns are frequent.
         Production equipment may not be as new as we
          would like them to be.
              “Stops and breakdown” stage.                               24/80
Dr. Tai-Yue Wang IIM Dept. NCKU
              Maintenance program
              implementation
      Production equipment typically becomes more
       sophisticated/complex.
           More expensive every year.
           It has greater economic impact.
                  Repairs should be done at a faster rate.
      Working shifts can also represent an obstacle for
       maintenance interventions.
           Limits possible maintenance tasks and scheduling.
Dr. Tai-Yue Wang IIM Dept. NCKU                                 25/80
              Maintenance program
              implementation
    The objective of maintenance is to efficiently
     oversee equipment throughout the equipment life
     cycle.
          Cover the entire lifecycle
                Implementing an effective corrective maintenance.
                Preventive maintenance tasks.
                Implementing predictive maintenance strategies.



Dr. Tai-Yue Wang IIM Dept. NCKU                                      26/80
              Getting started
     Become familiar with the resources that will
      require maintenance.
           Each maintained resource should be coded (resource
            id#).
     Code the types of breakdowns and maintenance
      tasks.
           In a historical data study -> Group failure causes.


Dr. Tai-Yue Wang IIM Dept. NCKU                                   27/80
         Getting started
    Maintenance should have the following two
     documents.
        Facility Inventory.
             Lists all equipments and their principle characteristics.
                  Code, record number, equipment type,…
        Equipment History Files.
                  Data given by the equipment manufacturer.
                Information about the location in the plant.

                Types of spare parts needed.

                …                                                        28/80
Dr. Tai-Yue Wang IIM Dept. NCKU
              Corrective maintenance
              implementation
                  Organize, in an effective way, the corrective
                   maintenance procedures and actions.
                        Breakdown occurs -> Fill out a breakdown
                         work order.
                              If the worker can solve it -> fill a report.
                              If not -> the work order will be sent to the
                               maintenance department.
                                     Work request order will be issued.
                                     Maintenance workers will either repair the machine
                                      immediately or will schedule the repair.
Dr. Tai-Yue Wang IIM Dept. NCKU
                                     The repair can be provisional or definitive.         29/80
              Scheduled corrective
              maintenance
     Variability in the corrective maintenance tasks
      duration can be problematic.
           Corrective orders and flow diagrams for repetitive
            repairs must be developed.
                 Materials and spare parts that should be utilized.
     Maintenance workers’ tasks do not end with the
      equipment repair.
           They should gather all the breakdown information.
           Describe the process that was performed.          30/80
Dr. Tai-Yue Wang IIM Dept. NCKU
              Scheduled corrective
              maintenance
     Each machine should have its own file with
      breakdown records.
          Analyze breakdown causes.
          Anticipate future problems.
          This file must be upgraded with each maintenance
           intervention.



Dr. Tai-Yue Wang IIM Dept. NCKU                               31/80
              Scheduled corrective
              maintenance
     Corrective maintenance tasks do not only consist
      on changing the broken or malfunctioning
      components.
          Study the causes and the frequency of the
           breakdowns.




Dr. Tai-Yue Wang IIM Dept. NCKU                        32/80
           Preventive maintenance
           implementation
    Avoid a breakdown of any resource, while
     keeping maintenance cost as low as possible.
    Two types of actions.
         Inspections.
              Observe and detect possible anomalies.
                   Frequent checkups that follow a specific inspection plan.
         Revisions.
              Scheduled equipment stops.
                        Systematic substitution of several machine components.
                       Carried out during the weekend.
Dr. Tai-Yue Wang IIM Dept. NCKU                                                   33/80
              Preventive maintenance
              implementation
     Preventive maintenance tasks’ scheduling is
      mandatory in the ISO norms.




Dr. Tai-Yue Wang IIM Dept. NCKU                     34/80
              Preventive maintenance
              implementation
       These tasks can be planned daily, weekly,
        monthly or even annually.
            Scheduled at times when they do not affect the
             factory’s production plan.
            Daily working problems force us to continuously
             reschedule these tasks.



Dr. Tai-Yue Wang IIM Dept. NCKU                                35/80
              Preventive maintenance
              implementation
       Equipment preventive maintenance tasks are
        also called PM orders.
            Each PM order should be based on a study of the
             equipment breakdown causes.
                   FMEA tool described at the tools section.




Dr. Tai-Yue Wang IIM Dept. NCKU                                 36/80
              Autonomous
              maintenance

      PM orders carried out by the production
       workers.
            Known as user maintenance orders.
      They should be simple and graphically
       represented.
            Many inspection tasks should be carried out every
             day.
Dr. Tai-Yue Wang IIM Dept. NCKU                                  37/80
              Autonomous maintenance
       Significant amount of notices that could be
        easily handled by the production worker.
             It takes more time to fill out the request order than to
              fix the problem




Dr. Tai-Yue Wang IIM Dept. NCKU                                    38/80
              Autonomous maintenance
       Autonomous maintenance includes these small
        tasks and three daily preventive measures.
             Cleaning, lubricating and checking.




Dr. Tai-Yue Wang IIM Dept. NCKU                     39/80
              Autonomous maintenance. Safety
       Safety is one of the most important
        restrictions.
             Autonomous tasks apply only for simple repair
              operations.
       Repair or maintenance should never be
        performed if the knowledge required to fix
        the machine is high.

Dr. Tai-Yue Wang IIM Dept. NCKU                               40/80
              Autonomous maintenance. Safety
       It can be very challenging to convince
        production workers about the importance of
        maintenance tasks.
             They do not consider their responsibility.




Dr. Tai-Yue Wang IIM Dept. NCKU                            41/80
              Autonomous maintenance
                  Autonomous maintenance implementation
                   process has a specific methodology.
                                  7   Autonomous Supervision
                                  6   Process Quality Assurance
                                  5   Autonomous Maintenance Standards
                                  4   Overall inspections
                                  3   Cleaning and Lubricating Standards
                                  2   Countermeasures to Sources of Contamination
                                  1   Initial cleaning


Dr. Tai-Yue Wang IIM Dept. NCKU                                                     42/80
              TPM - Total Productive
              Maintenance
      In the 1970s, Nakajima developed in Japan
       TPM.
           New maintenance management philosophy.
      English translation was not published until
       1988.
           JIPM – Japanese Institute of Plants Maintenance.
                Grants the PM prize to the TPM top excellent
                 companies.
                            60% of the winning companies during the first 17 years are now
                             part of the Toyota Group or suppliers of this Group.
Dr. Tai-Yue Wang IIM Dept. NCKU                                                          43/80
                  TPM - Total Productive
                  Maintenance
               Nakajima combined preventive
                maintenance theories with the total
                quality concept.
                     Nakajima developed the Overall Equipment
                      Efficiency ratio.




Dr. Tai-Yue Wang IIM Dept. NCKU                                  44/80
               TPM keys

        Maximize the Overall Equipment Efficiency.
              Eliminating the six big losses.
        Autonomous maintenance implementation.
              In order to terminate the “I operate, you repair”
               mind set.
        Preventive engineering.
              Improving the equipments’ maintainability.

Dr. Tai-Yue Wang IIM Dept. NCKU                                    45/80
          TPM keys

     Training workers for maintenance
      improvements.
         Propose methods for increasing the equipment
          availability.
     Initial equipment management.
     The objective of the TPM -> Zero
      Breakdowns.
              Utilize tools such as the P-M analysis -> Explained
               in tools section.
Dr. Tai-Yue Wang IIM Dept. NCKU                                  46/80
             RCM - Reliability Centered
             Maintenance
         RCM was created in the United States in the
          1960s, to optimize the reliability of
          aeronautical equipment.
               RCM was not utilized in nuclear power stations
                until the 1980s.
               Recently has been implemented in the industrial
                world.


Dr. Tai-Yue Wang IIM Dept. NCKU                                   47/80
             RCM - Reliability Centered
             Maintenance
         Needs a complete maintenance and
          breakdown record for each item of
          equipment.
               RCM objective is to determine the maintenance
                tasks that are more effective for the critical
                components.
                     FMEA, reliability analysis, statistical techniques.
               It is necessary to have a preventive maintenance
                program implemented and running properly.
Dr. Tai-Yue Wang IIM Dept. NCKU                                             48/80
              FMEA for equipment
       All defects have a root cause, and to eliminate
        future defects an action must be carried out.
            Defect -> Gap between two elements
            Cause -> Lack of lubrication or a loose fastener.
            Action -> Grease or tighten the lose element.




Dr. Tai-Yue Wang IIM Dept. NCKU                                  49/80
              FMEA for equipment
       To determine a good preventive maintenance
        plan, all the possible breakdowns, their causes
        and their corrective actions must be analyzed.
            The main tool to carry out this type of analysis is the
             FMEA for equipment (Failure Mode and Effects
             Analysis).
                   Is a guide to analyze, in an organized manner, causes of
                    possible equipment breakdowns.
                   A group of workers is gathered to study the problems and
                    failures
Dr. Tai-Yue Wang IIM Dept. NCKU                                           50/80
                FMEA for equipment
                                                                                           PAGE       OF
EQUIPMENT                                           CARRIED OUT BY                  DATE
   Equipment                                                              Actual    Recommended
    functions      Failure modes   Faiulre efects       Failure causes   controls      actions    Responsible




 Dr. Tai-Yue Wang IIM Dept. NCKU                                                                   51/80
                                                                                                                                               PAGE       OF
                                                       EQUIPMENT                                        CARRIED OUT BY                  DATE
                                                          Equipment                                                           Actual    Recommended
                                                           functions   Failure modes   Faiulre efects       Failure causes   controls      actions    Responsible




              FMEA for
              equipment
       Equipment functions.
             The functions that the equipment carries out.
                   Provides compressed air during specific conditions.
       Failure modes.
             All the possible ways that the equipment can be
              forced to stop.
                   Breaks, blockage, leaks, etc.


Dr. Tai-Yue Wang IIM Dept. NCKU                                                                                                         52/80
                                                                                                                                               PAGE       OF
                                                       EQUIPMENT                                        CARRIED OUT BY                  DATE
                                                          Equipment                                                           Actual    Recommended
                                                           functions   Failure modes   Faiulre efects       Failure causes   controls      actions    Responsible




              FMEA for
              equipment
       Failure effects.
             All possible consequences of each failure are
              analyzed in detail.
                   Severity (S).
                          1 being not very serious.
                          4 very serious or 10.




Dr. Tai-Yue Wang IIM Dept. NCKU                                                                                                         53/80
                                                                                                                                           PAGE       OF
                                                   EQUIPMENT                                        CARRIED OUT BY                  DATE
                                                      Equipment                                                           Actual    Recommended
                                                       functions   Failure modes   Faiulre efects       Failure causes   controls      actions    Responsible




              FMEA for
              equipment
       Failure causes.
             The origin of the failure is analyzed.
             Identify the anomaly that can lead to the failure.
                   Probability (P).
                         1 not very frequent.
                         4 very frequent or 10.




Dr. Tai-Yue Wang IIM Dept. NCKU                                                                                                     54/80
                                                                                                                                                 PAGE       OF
                                                         EQUIPMENT                                        CARRIED OUT BY                  DATE
                                                            Equipment                                                           Actual    Recommended
                                                             functions   Failure modes   Faiulre efects       Failure causes   controls      actions    Responsible




              FMEA for
              equipment
       Actual controls.
             If, at the present time, some kind of control is carried
              out.
             Detection (D)
                   1 if the control does not always detect the cause
                   4 if it always detects or 10.




Dr. Tai-Yue Wang IIM Dept. NCKU                                                                                                           55/80
              FMEA for equipment
               After the first part of the FMEA table has
                been completed, the Risk Priority Number
                (RPN) is calculated.
                     The product of the three quantified variables (S,
                      P and D).
                     Ranking failures by RPN.
                           Analyze the causes that do not represent any threat.
                           Special attention must be paid to those effects that
                            have been considered critical.
Dr. Tai-Yue Wang IIM Dept. NCKU                                                56/80
              FMEA for equipment
               The chosen plan of action and the employee
                responsible for carrying out this plan are
                registered in the same table utilized in the
                FMEA.
                     After a FMEA application arises, the necessity
                      of developing a preventive maintenance plan is
                      recommended.


Dr. Tai-Yue Wang IIM Dept. NCKU                                    57/80
                                                     Equipment
                                                   performance
                                                                                      Substitution




              FMEA for
                                                                 T = K·MTBF



              equipment                                                 MTBF
                                                                               MTTR

                                                                                                     Time




          Preventive maintenance intervention
           periods (T).
                Know the component damage/wear behavior
                 curve.
                      Breakdowns and the time when the breakdowns
                       occurred -> Mean Time Between Failures (MTBF).
                T is based on the corrective percentage that the
                 company would like to support (K).

Dr. Tai-Yue Wang IIM Dept. NCKU                                                                58/80
              Reliability
       Reliability is defined as the probability that an
        equipment will work satisfactorily, during a
        certain period of time under some specific
        working conditions.
       Reliability is a probability.
             Relative frequency of breakdowns.



Dr. Tai-Yue Wang IIM Dept. NCKU                             59/80
              Reliability
       All production equipment should work
        satisfactorily.
             Failure can be triggered by an abrupt change in the
              component characteristic or by progressive damage.
       Work satisfactorily for a specific period of time.
             Maintain quality standards during a reasonable
              period of time.
                   RELIABILITY = QUALITY + TIME

Dr. Tai-Yue Wang IIM Dept. NCKU                                60/80
              Reliability
           The component life or equipment life
            duration depends on working conditions.
                Environmental (temperature or humidity).
                Operational (continuous starts and stops,
                 electrical strain).




Dr. Tai-Yue Wang IIM Dept. NCKU                              61/80
              Reliability
           The system state depends on the primary
            group of elements that makes it work
            properly.
                Each element has a random lifetime.
                       Estimate the lifetime of the components.
           Reliability -> MBTF (Mean Time Between
            Failure)
                                            Operating time
                                  MTBF 
                                           Number of failures
Dr. Tai-Yue Wang IIM Dept. NCKU                                    62/80
                                                 Failures total time
                                        MTTR 
                                                 Number of failures


              Reliability and Maintainability
      Maintainability -> probability that it must be
       repaired in a predetermined time following a
       specific repair procedure.




Dr. Tai-Yue Wang IIM Dept. NCKU                               63/80
                                                         Failures total time
                                                MTTR 
                                                         Number of failures
              Reliability and Maintainability
      Maintainability depends on different factors.
           Machine factors.
                  Accessibility or interchangeability among components.
           Organizational factors.
                  Maintenance staff knowledge, documentation availability,…
           Operative factors.
                  Ability of the manpower.
      Is quantified through the MTTR (Mean Time To
       Recovery).                                 64/80
Dr. Tai-Yue Wang IIM Dept. NCKU
              Reliability and Statistical
              availability
        Average between the middle time used in the
         equipment and the required production time
                                            MTBF
          statistical availability 
                                         MTBF  MTTR

                TBF1              TBF2           TBF3
        If the different times between breakdowns as t
         well as each repair duration time are
                   TR1      TR2         TR3

         graphically represented this process.

Dr. Tai-Yue Wang IIM Dept. NCKU                           65/80
              Reliability - the Bathtub curve
      Is a graphic representation of the failure rate
       l(t).
           Probability that an element fails depending on its
            life use stage or status.
                  ZONE I. Infant period.
                  ZONE II. Useful period.
                  ZONE III. Waste period.
                                             l(t)

                                                    ZONE   ZONE   ZONE
                                                      I      II    III




Dr. Tai-Yue Wang IIM Dept. NCKU                                          66/80
                                                                           time
                Reliability – The bathtub curve:
                Zone I
                                 Equipment set up and debug process.
                                 Goes downhill because, as time moves
                                  forward, the probability of a
                                  component failure decreases.
                                 The problems in this area can be
                                  avoided by making intensive tests or
l(t)

         ZONE                ZONE
                                  by exchanging troublemaker elements
                                        ZONE
           I                   II        III
                                  at an early stage adjustment period.
Dr. Tai-Yue Wang IIM Dept. NCKU                                    67/80
                                               time
                    Reliability – The bathtub
                    curve: Zone II

NE               ZONE
                                         
                                       ZONE
                                              Zone II.
                   II                   III
                                                  Failures randomly appear.
                                                  Electronic systems.
                                                  time
                                                            The curve formed is virtually
                                                             horizontal.
                                                  In mechanical systems.
                                                            The curve normally has a slightly
               ZONE
                                                             positive slope.
                III




     Dr. Tai-Yue Wang IIM Dept. NCKU                                                             68/80
                            time
                    Reliability – The bathtub curve:
                    Zone III

NE               ZONE                  ZONE
                   II                   III
                                             Zone III.
                                                Failures come from components far
                                               time
                                                 more quickly.
                                               Critical components replacement is

                                                 strongly recommended.

               ZONE
                III




     Dr. Tai-Yue Wang IIM Dept. NCKU                                            69/80
                            time
                                       Defects


                                                                  sporadic losses




              P-M Analysis                                            zero losses




                                                 chronic losses
                                                                                    Time



    Defects reasons.
          Sporadic(零星) losses.
          Chronic(慢性) losses.
    Sporadic losses can be corrected using tools
     already studied.




Dr. Tai-Yue Wang IIM Dept. NCKU                                         70/80
                                               Defects


                                                                          sporadic losses




              P-M Analysis                                                    zero losses




                                                         chronic losses
                                                                                            Time



    The P-M analysis is responsible for eliminating
     chronic losses.
          Considered “natural” according to their root sources.
          P - > Phenomenon.
          M - > Mechanism.




Dr. Tai-Yue Wang IIM Dept. NCKU                                                 71/80
                                                       Defects


                                                                                  sporadic losses




              P-M Analysis                                                            zero losses




                                                                 chronic losses
                                                                                                    Time



     Reliability that has been studied has two aspects
      to consider.
          Intrinsic reliability.
                 Due to the design and production of the component.
          Operative reliability.
                 Due to the component use and the maintenance process.




Dr. Tai-Yue Wang IIM Dept. NCKU                                                         72/80
                                          Defects


                                                                     sporadic losses




              P-M Analysis                                               zero losses




                                                    chronic losses
                                                                                       Time



     P-M analysis should be applied after
      conventional improvement.
     Six sigma is also suitable to carry out this type
      of study.




Dr. Tai-Yue Wang IIM Dept. NCKU                                            73/80
              Maintenance management
     A maintenance department should properly
      manage and control their costs.
     Unlimited number of indicators that can be used
      for maintenance department performance.
           Manpower performance, hours dedicated to urgent
            work, repair cost, availability,...



Dr. Tai-Yue Wang IIM Dept. NCKU                               74/80
              Maintenance management
     Maintenance management is a difficult task
      because it frequently does not have
      management’s support.
           As long as the maintenance department does not
            exceed its assigned budget, no one pays much
            attention to the maintenance department activities or
            expenses.


Dr. Tai-Yue Wang IIM Dept. NCKU                                75/80
              Maintenance costs
      Using economic terms, maintenance
       management helps to control deviations in the
       firm’s budget and also to determine investment
       needs to reduce the costs.




Dr. Tai-Yue Wang IIM Dept. NCKU                     76/80
              Maintenance costs
      There are two alternatives or opposing costs.
           Non-maintenance costs.
                  Opportunity costs, quality costs, production manpower
                   cost, etc.
           Maintenance costs.
                  Breakdown prevention costs, anomalies detection cost,
                   inspection resources costs, etc.




Dr. Tai-Yue Wang IIM Dept. NCKU                                            77/80
                                  Cost

                                                  Total costs


              Maintenance                                       Maintenance costs




              costs                                         Non-maintenance
                                                            costs
                                              1
                                                                                    2

                                                                                                Availability
                                         0%                                             100 %




      (1) -> Maintenance investment increases the
       equipment availability and at the same time
      (2) -> An increase of the availability,
       supposes large investments.


Dr. Tai-Yue Wang IIM Dept. NCKU                                                                  78/80
              Summary
     This chapter has provided an overview of
      maintenance activities, a critical aspect of Lean
      Manufacturing. Maintenance planning and
      monitoring activities are critical factors for Lean
      Enterprise efficiency.




Dr. Tai-Yue Wang IIM Dept. NCKU                        79/80
              Summary
     Unfortunately, maintenance is normally
      perceived as a necessary evil, and is not always
      seen as a critical engineering activity. This
      chapter has outlined some of the maintenance
      policies and procedures that can be used to
      obtain the goal for any production system:
      operate as efficient as possible at the lowest cost.


Dr. Tai-Yue Wang IIM Dept. NCKU                         80/80

								
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