Process Failure Modes And Effects Analysis (PFMEA) Training

Process Failure Modesand Effects Analysis(PFMEA) TrainingNovember 2003

PFMEA Training1.0 What is a PFMEA?lA Process Failure Modes and Effects Analysis provides a structured,qualitative, analytical framework which taps the multi-disciplinedexperience of the team to brainstorm answers to such questions as:lHow can this process, function, facility, or tooling fail?lWhat effect will process, function, facility, or tooling failures have on theend product (or customer)?lHow can potential failures be eliminated or controlled?lBased on the success of Failure Modes and Effects Analysis (FMEA),the PFMEA concept was developed to incorporate a broader analysisteam to accomplish a thorough analysis in a short timelA PFMEA can be used to assess any process. The mostcommon use of the PFMEA involves manufacturing processeslPFMEAs may be performed on new processes or to improvecurrent processeslTo maximize its value, a PFMEA should be performed as early inthe manufacturing development cycle as possible1

PFMEA Training1.0 What is a PFMEA? (cont)lBecause most PFMEAs involve manufacturing area processes, themanufacturing engineer is usually the team leaderlThe effectiveness of the team depends upon the expertise of its members,and the quality of the team output depends on the willingness of each teammember to give his or her best effortlTeams may include:lManufacturing EngineerlDesign EngineerlTooling EngineerlSystem Safety EngineerlIndustrial EngineerlHandling SpecialistlLine Foreman/OperatorslCustomerlMaterials & Process EngineerlOthers as required2

PFMEA Training2.0 How to Conduct an Effective PFMEAlPrior to the first meeting, the team leadershouldlllEstablish objectives and scopeChoose experts for the PFMEA teamThe team leader is responsible for the effectiveness of thereviewlBrainstorming used to increase creativity and bring out a widerange of ideaslDiscussion allows team to look at things from different view pointslA visit(s) to the work area with an overview of the process/ test/operation gives team members basic understanding of theprocesslLimit meetings to one hour3

PFMEA Training2.0 How to Conduct an Effective PFMEA (cont)llSTEP 1lTeam leader organizes the team; defines the goals, methods, scope,responsibilities of each team member; and establishes a tentativeschedulelAfter reviewing engineering, drawings, and planning, team develops aflow chart showing the major functions or operations of the process tohelp team members understand the processSTEP 2lFor each process function, team determines all credible failure modeslTeam discusses and records the failure effects, failure causes, andcurrent controls for each potential failure modelTeam rates occurrence, severity, and detection for each failure causelIt is helpful to rate all failure causes for occurrence first, next rate for severity,and then rate for detectionlThe Risk Priority Number (RPN) is the product of these ratings4

PFMEA Training2.0 How to Conduct an Effective PFMEA (cont)lSTEP 3lIdentify corrective action to improve the process/testllFailure causes with the highest RPN should be analyzed firstlHigh occurrence number indicates the causes should be eliminated orcontrolledlHigh detection number indicates a need for additional controlslHigh severity number indicates product or process redesign may be neededConduct additional brainstorming to develop effective and innovativeways to reduce failurelProposed changes identified as “Resulting Action Taken” and newoccurrence, severity, detection, and RPN ratings are assigned5

PFMEA Training2.0 How to Conduct an Effective PFMEA (cont)lSTEP 4llProposed changes for high/significant RPN ratings that have notbeen completed are listed on the PFMEA form as “Open Work –Preventive Action Report (PAR) Required” along with applicablename and organizationlPFMEA team reaches agreement on items to keep open and carryforwardlAll “Open Work – PAR Required” items will be included in theexecutive summary of the PFMEA TWRlIndividual members will be responsible for the implementation oftheir respective “Open Work” itemsPresenting the PFMEA results to management and releasing thefinal report completes the PFMEA effort6

PFMEA Training3.0 PFMEA Team OrganizationlPFMEA team members are assigned to function as team leader,scribe, recorder, and facilitatorlTeam Member – uses personal knowledge, expertise, andperspective; participates in meetings helping the team reach fullpotentiallChecklistlBe preparedlBe innovative – Ask questions, challengeassumptionslComplete and close all action itemsassigned7

PFMEA Training3.0 PFMEA Team Organization (cont)lTeam Leader – responsible for planning, organizing, staffing, andchairing; ensures a thorough and credible PFMEA analysis isperformedlChecklistlSelect 5-10 team members to represent engineering organizations and/or workoperations involvedlSelect appropriate team members to function as scribe, recorder, and facilitatorlPrior to the first team meetinglDevelop scope for PFMEAlReview PFMEA guidelines and formslDevelop schedulelResolve any questions about performing the PFMEAl Distribute guidelines, objectives, scope, and schedule to each team memberlAfter each team meeting, review team’s progresslEnsure any required changes in engineering, planning, etc. are i ncluded in team’srecommendationsl Prepare final report and report all open action items8

PFMEA Training3.0 PFMEA Team Organization (cont)lScribe – record team members’ comments on white board or flip chartas the team brainstormsllChecklistlDocument comments on whiteboard/flip chartlGet team concurrence with what wasdocumentedlClarify comments as necessaryRecorder – record team’s thoughts as listed on board/chartlChecklistlRecord points outlined on white board or flip chartlExpand, summarize, and/or edit the ideas as they are recordedlProvide notes to the team leader or draft team minutes according tothe team leader’s directionlHelp complete PFMEA work sheets9

PFMEA Training3.0 PFMEA Team Organization (cont)lFacilitator – the system safety/reliability engineer is generally thePFMEA facilitator. The facilitator supports the team by enhancingprocess consistencylChecklistlProvide copies of PFMEA instructions and other materials to theteam leaderlAssist team leader in evaluating team performance as requestedlFunction as a consultant throughout the PFMEA analysislAssist team leader and team in effectively utilizing PFMEA analysis10

PFMEA Training4.0 PFMEA Form and DocumentationllThe PFMEA form provides the structured format for meetings,analysis, and documentation of findingsTwo variations of the form are available; use depends on thecomplexity of the process and/or potential need for reviewllLong form includes follow-up documentation for evaluation of initialrecommendations:lFirst time process reviewlNew processeslMajor process enhancements or changesShort form used for:lRepeat evaluatedlSimple processes11

PFMEA TrainingProcess Failure Modes and Effects Analysis (PFMEA) – Long dePotentialEffects ofFailurePotentialCause ofFailureCurrentControlsLegend:OCCSEVDETRPNOCC occurrenceSEV ctivity andStatusDET detectionRPN Risk Priority Number12

PFMEA TrainingProcess Failure Modes and Effects Analysis (PFMEA) – Short dePotentialEffects ofFailurePotentialCause ofFailureCurrent ControlsLegend:OCC occurrenceSEV severityOCCSEVDETRPNRecommended ActionsDET detectionRPN Risk Priority Number13

PFMEA Training4.0 PFMEA Form and Documentation (cont)lPotential Failure Modes – list all credible failure modes or waysthe process/test can fail before addressing failure effects andfailure causesl“What can possibly go wrong with this process/test?”l“How can the part (component, assembly, or product) fail to meetthe engineering criteria or specification?”lIn each instance, the assumption is made that the failure couldoccur, but will not necessarily occurlEach failure mode should be crediblelDo not list acts of God or freak accidentslExamples of failure modes edDeformedGougedMisaligned CorrodedBroken Tooling Wrong ToolingWrinkledHumidityScratchedHandling Damage14

PFMEA Training4.0 PFMEA Form and Documentation (cont)lPotential Effects of Failure – assuming the failure mode hasoccurred, list all potential failure effects of the process failurellWorst case effects such as “leakage past an O-ring seal” should beconsidered firstlLess serious failure effects such as “rework – schedule impact”may then be notedlIn each case, understand that a process failure can affect theimmediate process, the subsequent processes, the end item, enditem users, or the customerPotential Failure Causes – failure cause of each potential failuremode should be thoroughly discussed and listed by the teaml“What conditions can bring about this failure mode?”15

PFMEA Training4.0 PFMEA Form and Documentation (cont)lCurrent Controls – usually verification techniques; list allcontrols intended to detect or eliminate the failure causes thuspreventing the failure mode from occurringll“If a defect or process failure occurs, will it be detected orprevented by the current controls”?lIf current controls are adequate, no corrective action is neededlIf current controls are not adequate, corrective action shouldrecommend additional or enhanced controlsQuantitative vs Qualitative Evaluation – evaluating failures foroccurrence, severity, and detection may be accomplishedusing quantitative or qualitative techniques – the twomethods should not be combinedlQuantitative approach relies on numerical datalQualitative approach relies on team members’ experience,judgment, involvement, and participation16

PFMEA Training5.0 Occurrence RatinglWhen estimating the occurrence rating, consider the probability thatthe potential failure cause will occur and thus result in the indicatedpotential failure modelDisregard detection at this point in the processOccurrence Rating CriteriaCriteriaRemote probability of occurrence. The team is not aware of thisfailure having ever occurred.Low probability of occurrence. Relatively few failures have occurred.Moderate probability of occurrence. Occasional failure, but not inmajor proportionsRating12-34-5-6High probability of occurrence. Process has experienced higher thannormal failure rate7-8Very high probability of occurrence. Process failure is almost certain.9-1017

PFMEA Training6.0 Severity RatinglSeverity is the factor that represents the seriousness or impact of the failureto the customer or to a subsequent processlllSeverity of failure relates to process failure effects and is independent of occurrenceand detectionSeverity of a failure effect is therefore the same for all failure causesSeverity should be considered as though no controls are in placeSeverity Rating CriteriaCriteriaFailure would have very little effect on further processing or product performance.Low severity rating. Failures have minor effect on further processing or productperformance.Moderate severity rating. A failure that causes customer concern or program impact,but will not cause a Criticality 1 failure of the end item or an equivalent process failure.Rating12-34-5-6High severity rating. Failure causes severe impact to component or process and maycontribute to a Criticality 1 failure of the end item or an equi valent process failure.7-8-9Very high severity rating. Failure contributes to a known or highly probable Criticality 1failure of the end item or an equivalent process failure involving loss of life or a majorloss of manufacturing facilities1018