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Equipment reliability l1
This document provides an overview of equipment reliability training at different levels. It discusses measuring and improving equipment performance through metrics like Overall Equipment Effectiveness (OEE) and Total Effective Equipment Performance (TEEP). The training introduces reliability concepts and processes to apply reliability tools and methods. It aims to change culture from reacting to failures to preventing failures through early reliability considerations in equipment design, purchasing, and maintenance.
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Equipment reliability l1
- 1. 1 EQUIPMENT RELIABILITY TRAINING SERIES LEVEL1: AWARENESS
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- 3. 3 OBJECTIVESOBJECTIVES MINDSETMINDSET The BusinessCase for improving equipment performance in today’s environment Reliability’s relationship to equipment performance Importance of production’s sponsorship/ownership Change in culture: From reacting to failure to preventing failure CAPABILITYCAPABILITY Introduce key reliability concepts and terms Begin the understanding of how these reliability concepts relate to improving equipment performance Awareness of reliability resources at Whirlpool PROCESSPROCESS Offer processes to apply equipment reliability methods and tools INTRODUCTION TO EQUIPMENT RELIABILITYINTRODUCTION TO EQUIPMENT RELIABILITY
- 4. 4 EQUIPMENT RELIABILITY TRAININGSERIESEQUIPMENT RELIABILITY TRAINING SERIES Awareness • Importance of high levels of equipment performance • How to measure equipment uptime/downtime • Key reliability tools and how to apply to improving equipment performance Novice Practitioner Practitioner• A series of 4hr to 8hr training modules on selected reliability tools & methods Reliability Application Engineer • Local process understanding • Quantifies and reduces equipment losses • Applies reliability tools/methods Reliability Consultant Level 4 Level 5 Level 3 Level 2 Level 1 • Provides high level reliability & methods skills • How to set up business driven equipment performance goals • How to link performance goals to improvements in loss categories • Tools & methods to reduce losses (including maintenance strategies) • Development and achievement of reliability requirements in Design
- 5. 5 EQUIPMENT RELIABILITYEQUIPMENT RELIABILITY TRAININGSERIESTRAINING SERIES Reliability Awareness (4 Hrs) - at the completion of this training level, the person should be able to describe the following: Equipment Performance 1) The importance of high levels of equipment performance and lower (including maintenance) costs in today’s competitive marketplace 2) The key factors that affect equipment performance (5M’s) 3) Downtime categories and opportunities for improvement 4) The key elements of high level equipment performance measures (Efficiency, OEE and TEEP) 5) Can perform a simple OEE / TEEP calculation RAM Concepts/Reliability Basics 6) The concepts Reliability, Availability and Maintainability (RAM) and how each of these impacts equipment performance 7) The importance of defining function and failure 8) The difference between a repairable and a non-repairable system and the associated measures (MTTF, MTBF and MTTR) 9) The relationship between equipment reliability and process reliability 10) Conceptually define FMEA and FTA their applications
- 6. 6 EQUIPMENT RELIABILITYEQUIPMENT RELIABILITY TRAININGSERIESTRAINING SERIES Reliability Elements in the Asset Life Cycle 11) How, at a conceptual; level, reliability can be integrated into all phases of the Asset Life Cycle (the “7 Rights”) in order to achieve predictable and high levels of equipment reliability. Specifically, can describe the key reliability considerations in the equipment design, purchasing and maintenance phases of the Asset Life Cycle. 12) The important role that operational and maintenance strategies play in improving the reliability of existing equipment. How to optimize maintenance tasks to reduce costs and still be effective. Resources 13) Aware of the key support resources for reliability tools, methods and diagnostic technologies. Reliability Awareness (4 Hrs) - cont’d.
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- 8. 8 PERFORMANCE OBJECTIVES Equipment Performance Record,Categorize and Reduce Equipment Downtime Losses Understand and encourage the use of OEE and TEEP Charts
- 9. 9 Improvement Thrusts: •Extreme Price Competition • Forced to make substantial Price Reductions (lowers Profit $) The Need for Change • Reduce Costs • Improve Equipment Performance “30 / 30” TEEP INTRODUCTION TO EQUIPMENT RELIABILITYINTRODUCTION TO EQUIPMENT RELIABILITY
- 10. 10 EQUIPMENT PERFORMANCE Range andAverage of Key Equipment OverallEquipmentEffectiveness(OEE) 100% 85% 75% 65% 55% 45% 35% OEE = Good Product Made Expected Product World Class OEE Avg. 1992 1993 1994 1995 1996 1997 1998
- 11. 11 EQUIPMENT PERFORMANCEEQUIPMENT PERFORMANCE OPPORTUNITIESOPPORTUNITIES Reducedwastes Reduced cycle time Reduced inventory Reduced product variability More efficient use of direct labor Reduced maintenance costs - type of work (less reactive) - extent of work (reduce PM’s) Reduced schedule disruption Increased EVA Reduced capital expenditures InIn FocusFocus - 6 Sigma- 6 Sigma - 10X- 10X - AOP Goals- AOP Goals - Lean Manufacturing- Lean Manufacturing NeedsNeeds moremore focusfocus • Reduce Costs • Utilize the “hidden factory” -- Increase Uptime of existing equipment
- 12. 12 INTRODUCTION TO EQUIPMENTRELIABILITYINTRODUCTION TO EQUIPMENT RELIABILITY Equipment Performance Equipment Reliability Exercise
- 13. 13 INTRODUCTION TO EQUIPMENTRELIABILITYINTRODUCTION TO EQUIPMENT RELIABILITY Equipment Performance MethodsMaterials Machines Measures Manpower Reliability Maintainability — Develop — Design — Purchase — Fabricate — Install — Operate — Maintain — Store (How well equipment performs) The “Rights of Reliability:
- 14. 14 PARTNERSHIP WITH OPERATIONSPARTNERSHIPWITH OPERATIONS REDUCING COSTS IS A SHARED GOAL - Reducing Operations Cost - Reducing Maintenance Costs (but not sub-optimize) HIGH LEVELS OF EQUIPMENT PERFORMANCE - Important to Operation - Important to Capital Projects Team - Important to Maintenance OPERATIONS MUST LEAD IMPROVEMENT EFFORT - Operation “Owns” Asset - Operations Sets Performance Expectation - Operation has “most” control of improvement opportunities 25% of Downtime 75% of Downtime Maintenance Manufacturing
- 15. 15 • Measure • Measure •Measure THREE MOST IMPORTANT FACTORS INTHREE MOST IMPORTANT FACTORS IN IMPROVING PERFORMANCEIMPROVING PERFORMANCE
- 16. 16 EQUIPMENT/PROCESS EFFECTIVENESS MEASURESEQUIPMENT/PROCESSEFFECTIVENESS MEASURES Planned Losses Operational Losses Good ProductionSpeed Losses Quality Losses A B C D E (Total Time) (Scheduled Time) (Up Time) ( (O E E T E PEverallOEE quipment ffectiveness) = E/B TEEP otal ffective quipment erformance) = E/A • Weekends/Holidays • Shifts not worked • No Schedule • Breaks/Lunch • Meetings/Tours • Training • General Cleaning • PM’s • Capital Improvement • Development • Set-ups/Change-overs • No Personnel • No Material • Equipment Breakdown • Jams and Minor Stoppages • Support System Failures • Reduction from expected speed • Product not meeting First Pass Yield Specs, which includes: - Held Product - Defects/Waste/Scrap - Machine Rejects - Quality Samples - Rework • First Pass Yield (Product made right the first time)
- 17. 17 PERFORMANCE MEASURESPERFORMANCE MEASURES OEEis a measure of the amount of good product produced compared to the amount of product that could have been produced if the manufacturing system operated perfectly (no downtime, operating at its expected speed and all product conforming to specification) for its entire scheduled time. OEE = Scheduled Production Good Product Made (Units: Time (hrs) or Production Quantities) World Class OEE = 85%*
- 18. 18 PERFORMANCE MEASURESPERFORMANCE MEASURES TEEPis a measure of the amount of good product produced compared to the amount of product that could have been produced if the manufacturing system operated perfectly (no downtime, operating at its expected speed and all product conforming to specification) for the total amount of time (calendar time) over the time period under consideration. TEEP = Total Time Scheduled Time (Units: Time (hrs) or Production Quantities) Also, TEEP can be considered as follows: TEEP = OEE x Utilization (where Utilization = Total Time or Total Expected Units Good Product Made )
- 19. 19 OEE / TEEPOEE/ TEEP OEE = Efficiency X Performance Rate X Quality Actual Rate Expected Rate Good Product Made Total Product Made XXXXOEE = Uptime Scheduled Time World Class Equipment Performance (Performance Rate) (Quality) XXXXOEE = (Efficiency) 95%90% 99% = 85% OEE / TEEP can also be expressed in terms of a formula as follows: TEEP = Scheduled Time Total Time XX Good Product Time Scheduled Time TEEP = OEE XX Utilization
- 20. 20 EQUIPMENT RELIABILITY TRAININGSERIESEQUIPMENT RELIABILITY TRAINING SERIES The Real Value of measuring OEE/TEEP: •Understand causes of equipment downtime so that improvements can be made •OEE/TEEP is also as valuable as an Equipment Performance Measure
- 21. 21 OEE / TEEPOEE/ TEEP EXAMPLEEXAMPLE Time interval: 24 hrs. Shift worked: A & B (C not worked - no demand) Operational downtime Losses: 1.5 hrs equipment (mechanical) breakdown 1.3 hrs no material 1.2 hrs set up 4.0 hrs total loss 1 hr PM during A shift Speed loss: 5% Quality loss: 3% Determine: - categorize machine time losses - determine amount of time machine was at “standard” - calculate OEE & TEEP Total Time 24 hrs Solution: Planned Loss Operational Loss Speed Loss Quality Loss Good Product Time 8 hr. C Shift 1 hr. PM 9 hrs 4 hrs Uptime (Time Basis) Therefore Uptime = 11 hrs (by difference)
- 22. 22 OEE / TEEPOEE/ TEEP EXAMPLEEXAMPLE OEE = Good Product / Scheduled = 10.1 hrs / 15 hrs = 67% TEEP = Good Product / Total Time = 10.1 hrs / 24 hrs = 42% Speed Losses = Uptime x Speed Loss Rate = 11 hrs x (0.05) = 0.6 hrs Quality Losses = (Uptime - Speed Loss) x Quality Loss Rate = (11 hrs - 0.6 hrs) x (0.03) = 0.312 hrs Planned Loss Operational Loss Speed Loss Quality Loss Good Product Time 9 hrs 4 hrs 0.6 hrs 0.3 hrs ? hrs Total Time 24 hrs 10.1 hrsGood Product Time (by difference) = Scheduled Time Scheduled Time = Total Time - Planned Loss Scheduled Time = 24 hrs - 9 hrs = 15 hrs
- 23. 23 EQUIPMENT PERFORMANCE MEASURESEQUIPMENTPERFORMANCE MEASURES Listed Increasing Levels of SophisticationListed Increasing Levels of Sophistication I. II. III. IV. Use measures Use measures to drive improvement - awareness of amount of time equipment is not “scheduled” Use Performance Measures based on both Scheduled Time (OEE) and Total Time TEEP - baseline - reasons for downtime - improvement goals - use common definitions of uptime / downtime for benchmarking - use OEE as high level measure of equipment performance. Compare to World Class. Use consistent measures based on scheduled time
- 24. 24 Total Time Interval1 Wk. (7 days;168hrs) Scheduled Production Time 100 Hrs. Operational Downtime Material Problems 6 Hrs. Product Change Overs 6 Hrs. Equipment Related Downtime 4 Hrs. Operator Training Issues 4 Hrs. 20 Hrs. Planned Production Rate 10 Parts/Hr. Actual Output 720 Parts Good Parts (Meeting Specs) 700 Parts Calculate: Performance Measure Example Assume: - All downtime has been identified - Actual Speed Rate is less than expected - Losses ( in hrs) Planned, Operational, Speed and Quality - Good Product Time (in hrs): Good Quality & At Expected Speed - OEE - Teep
- 25. 25 EQUIPMENT RELIABILITY TRAININGSERIESEQUIPMENT RELIABILITY TRAINING SERIES Planned Loss Operational Loss Speed Loss Quality Loss Good Product Time ___ hrs ___ hrs ___ hrs ___ hrs ___ hrs Total time = Scheduled Time = Uptime =
- 26. 26 EQUIPMENT RELIABILITY TRAININGSERIESEQUIPMENT RELIABILITY TRAINING SERIES Planned Loss Operational Loss Speed Loss Quality Loss Good Product Time 68 hrs 20 hrs hrs hrs ? hrs Total time = Scheduled Time = Uptime = SOLUTION - data is given - obtained by difference 168 hrs 100 hrs 80 hrs Speed Loss: Parts @ expected speed = 80 hrs X 10 parts = 800 parts hrActual parts = 720 parts Speed Loss parts lost expected speed == 800 parts - 720 parts 10 parts/hr = 8 hrs
- 27. 27 EQUIPMENT RELIABILITY TRAININGSERIESEQUIPMENT RELIABILITY TRAINING SERIES Quality Loss: = parts lost expected speed = 2 hrs (Time) Planned Loss Operational Loss Speed Loss Quality Loss Good Product Time 68 hrs 20 hrs 8 hrs 2 hrs 70 hrs OEE = Good Product Time Scheduled Time = 70 hrs 100 hrs = 70 % TEEP = Good Product Time Total Time = 70 hrs 168 hrs = 42 % Also OEE = Good Parts Total Scheduled Time = 700 parts 100 hrs x 10 parts = 70 % hr 720 parts made - 700 parts good 10 parts/hr
- 28. 28 Record, Categorize andReduce Equipment Downtime Losses Understand and encourage the use of OEE and TEEP Charts PERFORMANCE OBJECTIVES Equipment Performance
- 29. 29 RAM Definitions, Measures& Tools
- 30. 30 • Describe thethree components of RAM • Record the “right” failure data – run time to failure – machine conditions at failure – by category • Use data to analyze failures – charts – measures (MTBF, MTTR, OEE, Availability) Performance ExpectationsPerformance Expectations RAM Definitions, Measures & Tools
- 31. 31David Garvin, ManagingQuality, Free Press, 1988 Quality -Quality - A New DefinitionA New Definition The QUALITY of some subject (i.e. of some product or process) means the extent to which the subject satisfies the expectations and needs of the users in operational environments over a period of time.
- 32. 32 Reliability =Reliability =Quality over TimeQuality over Time Reliability is the time dimension to quality. Product or processes that meet or exceed customer expectations, not just when they are new but over a period of time, are generally considered to have high reliability. Time may be some other measure than hours like footage, cycles, indexes, images, copies or actuations.
- 33. 33 What is Reliability?Whatis Reliability? When we speak of the reliability of a product or process we are using an umbrella term which includes the concepts of: Reliability Maintainability Availability Manufacturability Safety Serviceability other ....ilities
- 34. 34 Components of ReliabilityComponentsof Reliability RELIABILITY … How long will it last? MAINTAINABILITY … How long does it take to repair? AVAILABILITY … Is it capable of running when I need it? SAFETY … Could someone get hurt?
- 35. 35 Reliability is ProbabilityofReliability is Probability of SuccessSuccess Reliability is the probability that an item will perform its intended function adequately for a specified period of time under the specified operating conditions. ⇒Probability - A number between 0 and 1 ⇒Intended Function - What is it supposed to do? ⇒Time - For how long: 24x7x365 or many short runs? ⇒Operating Conditions - Where is it going to be installed?
- 36. 36 What is Failure?Whatis Failure? A product or process is said to have failed when it no longer performs its intended function adequately. Consider a fuse. Its job is to protect a circuit from overloading. If a fuse blows because there was an over-current spike, the fuse did its job. However, if there was a current spike and the fuse did not blow and the wiring caught fire, then the fuse failed! Therefore, function needs to be clearly defined.
- 37. 37 ReliabilityReliability Reliability is the probabilitythat an item will perform its intended function adequately for a specified period of time under the specified operating conditions. Example A packaging line is designed to fill 1000 multipacks of film without a failure. This constitutes one run. One hundred runs were initiated and 90 runs were completed successfully. The packaging line reliability can be estimated by R(t=1K) = = = 0.9 # of Successful Trials Total Number of Trials 90 100
- 38. 38 MaintainabilityMaintainability Maintainability is the probabilitythat an item can be restored to satisfactory operating condition within a specified period of time under stated conditions by personnel having prescribed skill levels, resources and procedures. Example A piece of equipment was designed so that all failures could be fixed in less than 30 minutes by entry level techs. Reviewing the most recent 100 service events, 15 of then took longer than 30 minutes to remedy. M(t=30) = = = 0.85 # of Successful Events Total Number of Events 85 100
- 39. 39 AvailabilityAvailability Availability is the probabilitythat an item, when used under given conditions, will perform satisfactorily when called upon. Example Nine times out of ten, when I walk up to the copier at 8AM, the copier is ready to process my job. It is not in STANDBY and does not have a sign stating that service has been called. A(t= 8) = = = 0.9 # of Successful Trials Total Number of Trials 9 10
- 40. 40 Repairable and NonrepairableDevicesRepairable and Nonrepairable Devices NONREPAIRABLE • One-shot device • If it breaks, throw it out. • Examples – Bearings – Light Bulbs – Electronic Components • Replacement strategies REPAIRABLE • If it breaks, fix it. • Employ preventive and predictive maintenance strategies. • Examples – Spoolers – Packaging equipment – Pumps – Knife sets Note: The distinction between repairable and nonrepairable devices is critical to how we collect and analyze data.
- 41. 41 How is ReliabilityMeasured?How is Reliability Measured? Number of Failures Life Cycle Cost Service/Repair Costs Reliability (Probability of Success) Availability Costs of Downtime, Waste B10, B50 Life Failure Rate MTTF (Mean Time To Failure) MTBF (Mean Time Between Failures) MTTR (Mean Time to Repair/Restore) OEE (Overall Equipment Effectiveness) TEEP (Total Effective Equipment Performance)
- 42. 42 ReliabilityReliability Reliability is the probabilitythat an item will perform its intended function adequately for a specified period of time under the specified operating conditions. Example A packaging line is designed to fill 1000 multipacks of film without a failure. This constitutes one run. One hundred runs were initiated and 90 runs were completed successfully. The packaging line reliability can be estimated by R(t=1K) = = = 0.9 # of Successful Trials Total Number of Trials 90 100 MEASURE S
- 43. 43 Mean Time ToFailureMean Time To Failure Mean Time To Failure (MTTF) applies to nonrepairable items. MTTF = Sum Failure Times Number of Failures Example: Run times to failure are 10,7,26,20,21,53,32,24,15,19 MTTF=227/10=22.7 hr Histogram of Failure Tim es 0.0 1.0 2.0 3.0 5 10 15 20 25 30 35 40 45 50 55 Time NumberofFailures MEASURE S H 10 20 30 40 50
- 44. 44 What Data ShouldBeWhat Data Should Be Collected?Collected? 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. MEASURE S
- 45. 45 Repairable SystemsRepairable Systems NEUTRAL/SAD/HAPPYSYSTEMS The order of the failure times is important. 32 43 51 65 17715 27 177 65 51 43 32 27 15 51 43 27 177 15 65 32 MEASURE S
- 46. 46 Mean Time BetweenFailuresMean Time Between Failures For Repairable Items, the arrival order of the failure times is important MEAN TIME BETWEEN FAILURES applies to “neutral” repairable items. Sum Inter-arrival Times Number of Failures MTBF = For example: 51+43+27+177+15+65+32 7 MTBF = = 410 7 = 58.6 51 43 27 177 15 65 32 MEASURE S
- 47. 47 For Repairable Equipment,WhatFor Repairable Equipment, What Data Should Be Collected?Data Should Be Collected? 1. Event Date 2. Clock Time 3. Machine clocks, meters, counters 4. Failure Mode What was seen/smelled/heard? 5. Machine Parameters What was the machine doing prior to the event? 6. Time to repair or restore Did the repair go smoothly? 7. What adjustments were made? 8. Parts used Were the parts broken? Were the replacements new or rebuilt? 9. Root cause of the stoppage What actually happened? 10. Failure Mechanism MEASURE S
- 48. 48 Mean Time ToRepairMean Time To Repair Mean Time To Repair (MTTR) applies to time actually spent performing a repair. MTTR = Sum Repair Times Number of Repairs Example: Repair times in hours for 10 cellular phones: 0.1, 0.6, 1.3, .05, 0.4, 1.1, 0.15, 0.1, 0.3, 0.2 MTTR=4.3/10=.43 hours Histogram of Repair Times 0 1 2 3 4 5 6 0.25 0.5 0.75 1 1.25 1.5 Time NumberofRepairs MEASURE S .25 .50 .75 1.00 1.25 1.50
- 49. 49 What Additional DataWhatAdditional Data Should Be Collected ForShould Be Collected For Repairs?Repairs? 1. 2. 3. 4. 5. MEASURE S
- 50. 50 AvailabilityAvailability Availability is theproportion of the the time the system is operating. Over a long period of time, AVAILABILITY is Uptime MTBF Uptime + Downtime MTBF + MTTR AVAILABILITY combines RELIABILITY AND MAINTAINABILITY. Note: This is the classical definition of Availability which excludes changeover time, scheduled maintenance and idle time. MEASURE S UP UP UP UP DOWN DOWN DOWN0 T A = =
- 51. 51 Reliability Measures SummaryReliabilityMeasures Summary There are a variety of RAM measures. One number, for example the MTBF, might not be adequate. For repairable systems, keep the data in time order and generate a time line plot. For nonrepairable data, a histogram does a good job of displaying the variability in the data.
- 52. 52 Intent of ReliabilityMethodsIntent of Reliability Methods To prevent failures from occurring To mitigate the effect of a failure To restore the system to a working state quickly if it did fail and, additionally, to measure and predict failure
- 53. 53 Methods to PreventFailuresMethods to Prevent Failures The best time to think about failure prevention is in the development and design phases of a project. RAM concepts in the project requirements and specification documents Robust Design Load/Strength Analysis Failure Mode, Effects & Criticality Analysis (FMECA) Fault Tree Analysis (FTA) Part Selection and Derating Flow Dynamics Analysis
- 54. 54 • Describe thethree components of RAM • Record the “right” failure data – run time to failure –machine conditions at failure –by category • Use data to analyze failures – charts –measures (MTBF, MTTR, OEE, Availability) Performance ExpectationsPerformance Expectations RAM Definitions, Measures & Tools
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- 56. 56 Reliability: New Equipment Recognizethe “Design for Reliability” Process Ensure reliability REQUIREMENTS exist. Base decisions on Life Cycle Costing. Include reliability SPECIFICATIONS in Requests for Quotes and Purchase Orders. Conduct formal reliability design reviews based upon FMECA guidelines. Enlist support from company experts. Request R.A.M information from vendors. Start involving cross functional team with new hardware early in the develop/design process. Performance ExpectationsPerformance Expectations
- 57. 57 ASSET LIFE CYCLEASSETLIFE CYCLE Project Launch Concept, Development and Design Final Engineering Purchase Fabricate Install Startup Commission Accreditation Operate and Maintain Decommission “PROJECT LIFE” LaunchConcept Design Execution Commissioning Utilization REMEMBER “PROJECT LIFE” IS NOT ASSET LIFE. THINK BEYOND PROJECT LIFE! End of Useful Life
Editor's Notes
- #32 One of the original definitions of Quality was conformance to specification. David Garvin - Professor at Harvard Business School His definition of quality goes beyond that put forth by Deming/Juran. Has the concept of performance past time zero. Change in definition parallels what has happened in the quality community: moved from QC (quality control of the product) to QA (quality assurance of the process)
- #33 Quality is performance at Time 0 Take it out of the box, plug it in, and turn the switch to ON. Does the motor start running? Reliability talks about the likelihood of it continuing to run once it started. Metrics: Electronics - Power-on Hours Mechanical Parts - Starts/Stops, cycles, indexes Continuous Processes - Footage, gallons
- #34 Other potential … ilities are Testability Diagnosability Flexibility We’ll spend a few minutes giving some basic definitions and examples of the first three terms and then will discuss some commonly used measures.
- #35 Rather than saying Reliability, Availability and Maintainability every time, we will use the acronym RAM. Think of our RAM with the big curly horns as an animal that is accustomed to butting heads with obstacles but will eventually be able to charge through the hole it created.
- #36 PROBABILITY - How many of you have ever been to a casino or bought a lottery ticket? What was your chance of winning? Somewhere between 0 and 1 and closer to 0 than to 1. - How likely is it that you could run 1 mile in 4 minutes or walk 1 mile in 1 hour? INTENDED FUNCTION ADEQUATELY (defined by situation) - Need to state clearly what equipment is intended to do. - What is the function of a screw driver? To turn a screw, to open a paint can, to prop open a window? - Even if you want to turn a screw, need to say either Phillips or straight, what size head, handle length, magnetic or not,… TIME What is the mission length: 24x7x365 or 8x5x50? Car travel: Drive to 5 miles in Spring or to 2000m in winter? OPERATING CONDITIONS Climate controlled room or ambient? EMI shielding? Is it fixed or portable?
- #37 The idea of defining a FAILURE in the context of NOT performing the STATED FUNCTION is a critical concept. How can we say something is doing or not doing a good job if the performance criteria have not been stated clearly, unambiguously?
- #38 INTENDED FUNCTION: To load rolls of film into a carton called a multipack MISSION LENGTH: 1000 multipacks = 1 run If the mission length were less than 1000 packs, then the reliability might have been higher than 90%. FAILURE: No equipment breakage, not cause damage to carton or contents. However, people rarely talk about a product or process being 90% or 80 % reliable after some amount of usage. They use some other metrics which we will discuss later.
- #39 Key words are PROBABILITY A number between 0 and 1 SATISFACTORY OPERATING CONDITION Again, need a definition of what is satisfactory SPECIFIED PERIOD OF TIME What is the downtime standard against which you are checking? STATED CONDITIONS Are they working on scaffolding, outdoors in winter with gloves…? PRESCRIBED SKILL LEVELS, RESOURCES, PROCEDURES What training do the people have, what tools will they have and where will they be located, what guidelines or procedures will they be able to use?
- #40 Key words are PROBABILITY A number between 0 and 1 GIVEN CONDITIONS Excludes abuse or unusual demands PERFORM SATISFACTORILY What is the standard against which satisfactory performance is compared?
- #41 Not all potentially repairable items are repaired. If the cost of repair is close to the cost of a new item, it is usually scrapped. Circuit boards costing less than $400 are thrown away. So they become nonrepairable by definition. The distinction between repairable and nonrepairable really becomes important when we analyze data and report performance using a reliability measure
- #42 Note: Reliability = RAM in its umbrella sense Life Cycle Cost: The total cost of a resource from inception through decommissioning. Pay me now or pay me later Service/Repair Costs: Might also include the cost of downtime and waste B10 Life: 10th percentile of failure of the life distribution B50 Life: 50th percentile of failure or the median life What is the difference between MTTF and MTBF? Not just a spelling error Goes back to previous discussion of repairable and nonrepairable devices MTTF is used for nonrepairable items and time to first failure of repairable items. Repair: Active wrench time, just doing the fixing Restore: Travel, diagnose, fix, certify, enter in database
- #43 INTENDED FUNCTION: To load rolls of film into a carton called a multipack MISSION LENGTH: 1000 multipacks = 1 run If the mission length were less than 1000 packs, then the reliability might have been higher than 90%. However, people rarely talk about a product or process being 90% or 80 % reliable after some amount of usage. They use some other metrics which we will discuss later.
- #44 Assume the data are from a small fan, called a muffin fan, that is used for cooling in many computers. You can take the data, put it into your calculator or a computer program, and get the mean or arithmetic average = 22.7 hours. Highly recommend that you PLOT the data as a histogram. A histogram is an excellent tool for showing the spread of the data (fan life). If your goal is to have a fan that will survive more that 40 hours of use, then there is much to be learned by investigating why one fan of ten lasted for more than 50 hours. 90% failed on or before 40 seconds, 10% survived >40 sec What additional data should you collect to aid in your investigation?
- #45 Situation: Too many fans are failing after as short amount of time. Your job is to improve the field life. Solicit input from people in class what additional data should be collected. Like a toe-tag on a body in a detective story Examples are: Duty Cycle Environment: Temperature, rH, dirt Stresses Manufacturer Batch within a manufacturer What was happening with the system when the item failed
- #46 Each line represents the service histories of three machines since their installation. The numbers on the lines are the run times and the vertical line indicates a failure. The downtime is not shown. If you were to draw a face in the box which represents the state of the system now, would you draw a Happy face, a Sad face or a Neutral face and why? For the Happy system, when would you predict the next failure to be? (Answer: Greater than 177 hours). For the Sad system, when would you predict the next failure to be? (Answer: Less than 15 hours) What about the Neutral System? If you look closely at the data on each line, what do you observe? (Answer: The numbers are all the same, just reordered. Average is less than 60 hours). If Happy, underestimate current performance if use the average. Opposite with Sad.
- #47 Mean Time Between Failures can always be calculated regardless of whether the system is happy, sad or neutral. It is the interpretation of the current status of the equipment that is incorrect: Underestimate MTBF if Happy Overestimate MTBF if Sad
- #48 Many of the items suggested for the nonrepairable items are valid for repairable but additional data are needed so that the events are kept in chronological order. Repairable items should be identified uniquely so that they can be tracked from the manufacturing line to the repair shop to inventory and back to possibly a different manufacturing line. Need to understand if the repair was done well. Kodak is authorized repairshop for pumps, motors How many times can an item be repaired before it is no longer usable?
- #49 Assume the data are from the repair of cellular phones. You can take the data, put it into your calculator or a computer program, and get the mean or arithmetic average time to repair = .43 hours. Highly recommend that you PLOT the data as a histogram. A histogram is an excellent tool for showing the spread of the data (repair time). If your goal is to do all repairs in less than 1.0 hour, then need to investigate why 2 repairs took longer. What additional data should you collect to aid in your investigation?
- #50 Solicit input from people in class of what additional data should be collected for Repairs. Examples are: What actually was done to the phone - parts replacement or an adjustment? Some types of repairs take longer than others. Were the phones identical - same vendor, same model? Some models are easier to disassemble and troubleshoot than others Who did the repair - person’s level of experience? How many times has the item been repaired before this? What was the date and time of the repair? If it is 3 AM, repair person might not be awake.
- #51 Border wars can be fought over the definition of AVAILABILITY. The Inherent Availability is the best the system can be and uses only the sum of the actual running times divided by the sum of the running times and downtime associated with active repair. The downtime if for active wrench time. It does not include thelogistics delay time of getting a person there, diagnosing the problem, getting the parts/tools, restoring the system. Downtime does not include other non-repair stoppages like product changeovers and idle time. Operational Availability takes some of these issues into account but is outside the scope of this discussion.
- #52 Quick summary of material which started with the Ruler. No real need for discussion.
- #53 The Reliability Professional’s first job is to prevent failures from occurring. A list of methods to attempt to prevent failures is on the next slide Ideally, anticipate what could go wrong and change the design so that the event cannot occur. Given that all failures cannot be prevented, try to have the item fail soft rather than hard. Have a drive system coast to a stop rather than to a screeching halt. Use condition-based indicators to warn of impending problems. If the item is in a failed state, have diagnostics built-in and troubleshooting procedures written so that the repair staff can do their work efficiently.
- #54 Methods to Prevent Failures should include anything involved in the up front planning for a project that has a reliability and maintainability nuance. RAM Specs should be a part of the overall project specification . They should reflect the needs of the client, operations and maintenance. Robust Design - Designing a process so that it is insensitive to noise variables Load/Strength Analysis - Strength of materials under repeated loads FMECA - A systematic approach for looking at potential failure events and their effects with the intent of lessening their likelihood of occurrence and lessening their effect if they do occur - Bottom Up Fault Tree Analysis - Starts with and undesired Top Event and asks what events singly or in combination could have caused it to occur Part Selection and Derating - Recommended parts based on prior experience, using motors at lesser stresses to extend their life Flow Dynamics Analysis - How fluids flow through pipes and couplings, how cooling air should be ducted through equipment
- #58 New Equipment Reliability This part of presentation deals with how do we build reliability into the new equipment we’re designing, buying, integrating, etc This could apply to new equipment or upgrades. (If your area has a capital budget review capital budget numbers with group) This diagram is probably representative of the way project managers/engineers/designers look at projects -- with utilization showing up as just a small part of the picture. But within utilization is usually the majority of the costs. This needs to be considered on a project. Need to look beyond “Project Life” as a goal for engineering & design community. Importance of identifying longterm ongoing costs which will be incurred during the utilization phase. These long term costs can be dramatically affected (positively and negatively) by what you do in the design, fabrication, purchasing, installation and commissioning. What you do in design directly affects Life Cycle costs. Lowest purchase price is not always the best solution. Need to identify life cycle cost, the total cost of an asset during its life. Goal of corporation is lowest Life Cycle Cost and highest Net Present Value. Example - need to appreciate intended use and life of product. Example used was different grades of quality of tools. Highest quality and cost --SNAP-ON TOOLS Mid range quality and cost -- CRAFTSMAN Low quality and cost -- K MART Special Which tools would you use if worked on Bobby Hamilton’s pit crew? Which tools would you use if were a backyard handyman? Which tools woul you use if were going to use tools only once?