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1、-Failure Mode & Effect AnalysisSix Sigma Black Belt Measure Phase 1FSB-S-M08 AObjectives1.Introduce the concepts of Failure Modes and Effects Analysis (FMEA)2.Provide a tool for analysing the risk of failure within a product or process.3.Provide a tool for further exploration of cause and effect rel
2、ationships2FSB-S-M08 AFMEAFailureModeFMEA Basics - Definition and PurposenA systematic method to:-Recognize, evaluate, and prioritize potential failures and their effects-Identify actions which could eliminate or reduce the chance of potential failure occurring-Document the processnThe way in which
3、the component, subassembly, product, or process could fail to perform its intended function. Failure modes may be the result of upstream operations or may cause downstream operations to fail.3FSB-S-M08 AThe outcome of the occurrence of the failure mode on the system, product, or process. The “IMPACT
4、” on the customer.FailureEffectsDefinition and Purpose (cont.)nWhy use an FMEA?nIdentify potential failure modes and rate the severity of their effectsnRank order of potential deficienciesnFocus on prevention4FSB-S-M08 AProcess Map Link to FMEAIdentify output failures and impactsAssess inputsPriorit
5、izeDetermine actions and impactY OutputsXX InputsXf(x)5FSB-S-M08 AWhen to Use an FMEAnEarly in the process improvement investigation, after a process map has been developednWhen new systems, products, and processes are being designednWhen existing designs or processes are being changednWhen carry-ov
6、er designs are used in new applicationsnAfter system, product, or process functions are defined, but before specific hardware is selected or released to manufacturing (ideally)6FSB-S-M08 AStarting with C&E MatrixnAdvantage -The Cause & Effect Matrix assists the team in defining the important issues
7、that the FMEA should address by helping to prioritize:-Important customer requirements-Process inputs that could potentially impact these requirements-Prioritizing the Key Process Inputs according to their impact on the Output variables (We want to focus on Inputs that highly impact a large number o
8、f Outputs first)nThe C&E Matrix also provides quantitative output that can be used in the determination of the specific severity ratings for the next stage of the FMEA process. 7FSB-S-M08 AOverviewWhat is the Process StepWhat can go wrong with the Process step?What is the Effect on the Outputs?What
9、are the Causes?How Bad?How Often?How can this be found?How well?What can be done?File: FMEAform.xls8FSB-S-M08 AFailure Mode 1Failure Mode 2Effect 1Failure Mode 1Effect 1Effect 2Linking Failure Modes to EffectsNote that the relationship between the Failure Mode and the Effect is not always 1-to-1Fail
10、ure Mode 1Failure Mode 2Effect 1Effect 29FSB-S-M08 AFMEA Procedure Overview10FSB-S-M08 AFMEA WorksheetBefore we move to the example lets look at an FMEA worksheet. The information on this sheet is transferred directly to the FMEA form. The purpose of this worksheet is to focus the team on the FMEA i
11、nputs and not on scoring. The scoring should be done after the basic inputs have been made.11FSB-S-M08 AThe Cold Cup of TeaPotential CustomerKettleCupMilk, Sugar, Spoon, TeaBoil WaterS InstructionsNBoil TimeNBoil TemperatureNPersonnel SkillsNTime to pour after boilingPlace Tea In Cup CCup AvailableX
12、 Pour Dwell/Stall TimeCCup StableCTea Bag in CupCSoak TimeSOP Stir during SoakSOP Stir after soakNPersonnel SkillsNLocationC Wrong cupN Cup MaterialAdd Milk, SugarSOP Milk AvailabilitySOP Sugar AvailabilitySOP Spoon AvailabilitySOP Cleanliness of SpoonX Dwell time to pour milkX Dwell time to deliver
13、 sugarX Dwell time to stirN LocationN Personnel SkillsServeX Walk distanceX Dwell time to serveN Customer expectations on temperatureCorrect Tea PreparationCorrect Temperature of Pouring Water for TeaCorrect Tea Drink PreparationTea reaches customer at right temperatureKey (xs)Input ClassificationsX
14、 CriticalC ControllableS SOPN Noise12FSB-S-M08 APLACE TEA IN CUPADD MILK, SUGAR IN CUPSERVEBOIL WATERStep 1: Write the Product or Process NameProducing a Cup of TEA13FSB-S-M08 AEXPECTED OUTPUT (Ys)Temperature (T degrees)Time (t mins)SERVETea reached customer at right temperatureTaste Quality (q sigm
15、a)Step 2: List the Process Steps Under InvestigationProducing a Cup of TEAServe Walk distance Dwell time to serve Customer expectations on temperature14FSB-S-M08 AT Degrees too lowQ sigma to lowFAILURE MODE “Negative Ys”EXPECTED OUTPUT (Ys)T mins too highStep 3: List the Potential Failure Mode(s)Tem
16、perature (T degrees)Time (t mins)Taste Quality (q sigma)Serve T Degrees too low15FSB-S-M08 AT Degrees too lowReplaceDisappointed customerFAILURE MODEEFFECTSCorrect T Degrees EXPECTED OUTPUT (Ys)Step 4: List the Potential Failure EffectsServe T Degrees too Replace low16FSB-S-M08 AFAILURE MODECAUSESEX
17、PECTED OUTPUT (Ys)T Degrees too lowExcessive Dwell TimeWalk Distances too longCustomer expectations changedIncorrect cup materialCorrect T DegreesCause of the FailureWhat can go wrong with inputs?Describes the conditions about the failure mode.Step 5: List the Causes of Each Failure ModeServe T Degr
18、ees too Replace Excessive low Dwell Time17FSB-S-M08 AT Degrees too lowTimer + Buzzer for dwell timeDistance Time included in Dwell TimeNoneStandardised on cup materialFAILURE MODECAUSESEXISTING CONTROLSControlThe current mechanisms in place which prevent or reduce the cause from occurring, or detect
19、 it before the product reaches the customer.Step 6: List Existing ControlsExcessive Dwell TimeWalk Distances too longCustomer expectations changedIncorrect cup materialServe T Degrees too Replace Excessive Timer + Buzzer low Dwell Time18FSB-S-M08 AuOn a 1 - 10 scale rate the seriousness of the effec
20、t of the potential failure mode to the customer.uWhen you have different effects dependent on which customer you are describing, select the rating for the worst effect of the failure mode.uGenerally, the only way to reduce the Severity is through a design change.SeverityAn assessment of how serious
21、the effect of the potential failure mode is to thecomponent / customer. The customer, in this case, can be the next operation, subsequent operations or the end user. Step 7: Establish a Rating Scale for SeverityServe T Degrees too Replace 8 low 19FSB-S-M08 AuOn a 1 - 10 scale rate the likelihood tha
22、t the specific causes listed will happen while the process performs. Historical data from similar processes, if available, may be helpful.uRemoving or controlling the causes through a design or process change is generally the only way to reduce the Occurrence Rating.OccurrenceAn assessment of the li
23、kelihood that a particular cause will happen and result in the failure mode and effect of the given severity.Step 7: Establish a Rating Scale for Probability of CausesServe T Degrees too Replace 8 Excessive 5 Low Dwell Time20FSB-S-M08 AuOn a 1 - 10 scale the probability that the current process cont
24、rols will detect the failure mode before it is too late (e.g., product leaves this process step, on to the next process step).uWhen multiple detection methods are listed, pick the best (lowest) rating.DetectionAn assessment of the likelihood that the current control mechanisms will detect the cause
25、of the failure mode (defect) before it reaches the customer.Step 7: Establish a Rating Scale for Effectiveness of ControlServe T Degrees too Replace 8 Excessive 5 Timer + Buzzer 3 low Dwell Time21FSB-S-M08 AnImpact of effect on process or customernProbability or frequency of causenEffectiveness of c
26、urrent controlStep 8: Select and Enter ScoresServe T Degrees too Replace 8 Excessive 5 Timer + Buzzer 3 low Dwell Time22FSB-S-M08 AuThe Risk Priority Number (RPN) is a measure of the process risk.uThe RPN is the product of the Severity Rating, Occurrence Rating, and the Detection. You may choose to
27、rank the RPNs from high to low on a Pareto chart. Provides a relative priority of the failure mode.uThe FMEA team must take corrective action for the high RPNs to reduce risks. Even if the RPN is low, some action should be taken if the Severity is high.SEVERITY OF THE EFFECTPROBABILITY OF OCCURRENCE
28、DETECTION DIFFICULTYRISKPRIORITYNUMBERXX=CALCULATE RISKOPPORTUNITESStep 9: Calculate and Rank the RPNsServe T Degrees too Replace 8 Excessive 5 Timer + Buzzer 3 120 low Dwell Time23FSB-S-M08 AWhen the RPNs have been calculated and failure modes have been rank ordered, corrective actions must be init
29、iated for the highest priorities. The objective of the corrective actions is to reduce any one or all of the Severity, Occurrence and Detection Ratings. This can be done by Designed Experiments (DOE) to better understand causes, improved control plans, improved processes, etc. The Ratings can be red
30、uced by:Severity Rating-Generally, the only way to reduce the Severity is through a design change.uOccurrence Rating-Removing or controlling the cause through a design or process change is generally the only way to reduce the Occurrence Rating.uDetection Rating-Improving the control methods are gene
31、rally the only way to reduce the Detection Rating.Step 10: Develop Recommended Actions Serve T Degrees too Replace 8 Excessive 5 Timer + Buzzer 3 120 Start timer Me Jan 01, 2001 low Dwell Time when kettle boils24FSB-S-M08 AAfter the recommended action has been identified, predict and record the subs
32、equent severity, occurrence, and detection rating.Step 11: Recalculate RPNsServe T Degrees too Replace 8 Excessive 5 Timer + Buzzer 3 120 Start timer Me Jan 01, 2001 8 3 3 72 low Dwell Time when kettle boils25FSB-S-M08 AWhy Wars Are LostLostNailLostShoeLostHorseLostRiderLostMessageLostBattleLostWar2
33、6FSB-S-M08 AFMEA ModelControlsEffectExternal customer or downstream process stepCauseFailure Mode(Defect)Process StepMaterial or process inputPreventionDetectionDetectionDetectionWhich is best case? Which is worst case?27FSB-S-M08 AFMEA - Excercisen Create a Failure Modes and Effects Analysis (FMEA)
34、 from the previous C&E exercise28FSB-S-M08 ASummarynThe FMEA is a systematic method to:Recognize and evaluate and prioritize potential failures and their effectsIdentify actions which could eliminate or reduce the chance of potential failure occurringDocument the processnThe FMEA procedure includes steps to:Identify output failures and impactsAssess inputsPrioritiseDetermine actions to take and the potential impact of those actions29
