Failure modes effect analysis
- 1. FAILURE MODES EFFECT ANALYSIS (FMEA)
- 2. WHAT IS FMEA? A systemized group of activities designed to: ▪ recognize and evaluate the potential failure of a product/process and its effects ▪ identify actions which could eliminate or reduce the chance of potential failure ▪ document the process Failure Mode and Effect Analysis
- 3. FAILURE MODE AND EFFECT ANALYSIS Simply put FMEA is: a process that identifies all the possible types of failures that could happen to a product and potential consequences of those failures.
- 4. FMEA TERMS Failure mode - the way in which something might fail Effects analysis – studying the consequences of the various failure modes to determine their severity to the customer.
- 5. 5 WHAT IS FMEA? FMEA--a tool to identify risks in your process Can be used in multiple places in process improvement Determine where problems are Help identify cause/effect relationships Highlight risks in solutions and actions to take Starts with input from processes Identifies three risk categories Severity of impact Probability of occurrence Ability to detect the occurrence
- 6. 6 WHEN TO USE Early stages (Define) to understand process and identify problem areas Analyze data (Analyze) to help identify root causes Determine best solutions (Improve) with lowest risk Close out stage (Control) to document improvement and identify actions needed to continue to reduce risk
- 7. THE REASONS FOR FMEA Get it right the first time Identifies any inadequacies in the development of the product Tests and trials may be limited to a few products Regulatory reasons Continuous improvement Preventive approach Team building Required procedures
- 8. FMEA PROVIDES THE POTENTIAL TO: Reduce the likelihood of customer complaints Reduce the likelihood of campaign changes Reduce maintenance and warranty costs Reduce the possibility of safety failures Reduce the possibility of extended life or reliability failures Reduce the likelihood of product liability claims
- 9. BENEFITS Identify potential and known failures Reduce the number of engineering changes Reduce product development time Lower start-up costs Greater customer satisfaction Increased cooperation and teamwork between various functions Continuous improvement
- 10. TYPES OF FMEA System - focuses on global system functions Design - focuses on components and subsystems Process - focuses on manufacturing and assembly processes Service - focuses on service functions Software - focuses on software functions
- 11. TYPES OF FMEA
- 12. CONCEPT FMEA Used to analyze concepts in the early stages before hardware is defined (most often at system and subsystem) Focuses on potential failure modes associated with the proposed functions of a concept proposal Includes the interaction of multiple systems and interaction between the elements of a system at the concept stages.
- 13. DESIGN FMEA Aid in the objective evaluation of design requirements and design alternatives Aid in the initial design for manufacturing and assembly Increase the probability that potential failure modes have been considered Provide additional information to aid in the planning of efficient design testing
- 14. PROCESS FMEA Indentify potential product related process failure modes Assess the potential customer effects of the failures Indentify the potential manufacturing causes on which to focus on Develop a ranked list of potential failure modes Document the results of the manufacturing
- 15. APPLICATION EXAMPLES Manufacturing: A manager is responsible for moving a manufacturing operation to a new facility. He/she wants to be sure the move goes as smoothly as possible and that there are no surprises. Design: A design engineer wants to think of all the possible ways a product being designed could fail so that robustness can be built into the product. Software: A software engineer wants to think of possible problems a software product could fail when scaled up to large databases. This is a core issue for the Internet.
- 17. FMEA WORKSHEET Process or Product Name Prepared by: Page _____ of ______ Person Responsible Date (Orig) ___________ Revised __________ Process Step Key Process Input Potential Failure Mode Potential Failure Effect S e v Potential Causes O c c Current Controls D e t R P N Actions Recommended S e v O c c D e t R P N Sev - Severity of the failure (what impact will it have on our process?) Occ – How likely is the event to occur (probability of occurrence) Det – How likely can the event be detected in time to do something about it RPN – Risk Priority Number (multiply Sev, Occ, and Det)
- 18. 18 HOW TO COMPLETE THE FMEA General Suggestions Use large white board or flip chart with a FMEA form drawn on it during the generation phase Focus the team on the specific area of study (product or process). Have process map available Have all subassemblies and component part of a product.
- 19. FMEA PROCEDURE 1. For each process input (start with high value inputs), determine the ways in which the input can go wrong (failure mode) 2. For each failure mode, determine effects Select a severity level for each effect 3. Identify potential causes of each failure mode Select an occurrence level for each cause 4. List current controls for each cause Select a detection level for each cause Process Steps
- 20. FMEA PROCEDURE (CONT.) 5. Calculate the Risk Priority Number (RPN) 6. Develop recommended actions, assign responsible persons, and take actions Give priority to high RPNs MUST look at severities rated a 10 7. Assign the predicted severity, occurrence, and detection levels and compare RPNs Process Steps
- 21. SEVERITY, OCCURRENCE, AND DETECTION Severity Importance of the effect on customer requirements Occurrence Frequency with which a given cause occurs and creates failure modes (obtain from past data if possible) Detection The ability of the current control scheme to detect (then prevent) a given cause (may be difficult to estimate early in process operations). Analyzing Failure & Effects
- 22. RATING SCALES 2 2 There are a wide variety of scoring “anchors”, both quantitative or qualitative Two types of scales are 1-5 or 1-10 The 1-5 scale makes it easier for the teams to decide on scores The 1-10 scale may allow for better precision in estimates and a wide variation in scores (most common) Assigning Rating Weights
- 23. RATING SCALES 2 3 Severity 1 = Not Severe, 10 = Very Severe Occurrence 1 = Not Likely, 10 = Very Likely Detection 1 = Easy to Detect, 10 = Not easy to Detect Assigning Rating Weights
- 24. RISK PRIORITY NUMBER (RPN) RPN is the product of the severity, occurrence, and detection scores. Severity Occurrence Detection RPNX X = Calculating a Composite Score
- 25. PROCESS FOR FMEA Process to Change Oil in a Car 3000 miles driven Drive car on lift Fill with new oil Drain Oil Replace Filter Take Car off lift Process Complete
- 26. HOW TO COMPLETE THE FMEA Step 1. Complete header information Step 2. Identify steps in the process Step 3. Brainstorm potential ways the area of study could theoretically fail (failure modes) Suggestion: Use Affinity Diagram as a brainstorming tool
- 27. FMEA WORKSHEET Process or Product Name Change Oil in Car Prepared by: Leon Page _1____ of __1____ Person Responsible Leon Mechanic Date (Orig) __27 Sep 2007___ Revised __________ Process Step Key Process Input Potential Failure Mode Potential Failure Effect S e v Potential Causes O c c Current Controls D e t R P N Actions Recommended S e v O c c D e t R P N Fill with new oil New Oil— Mech anic Wrong type of oil Engine wear No oil added Engine Failure Sev - Severity of the failure (what impact will it have on our process?) Occ – How likely is the event to occur (probability of occurrence) Det – How likely can the event be detected in time to do something about it RPN – Risk Priority Number (multiply Sev, Occ, and Det)
- 28. 28 HOW TO COMPLETE A FMEA Step 4 For each failure mode, determine impact or effect on the product or operation using criteria table (next slide) Rate this impact in the column labeled SEV (severity)
- 29. 29 SEVERITY (SEV) RATING SEV Severity Product/Process Criteria 1 None No effect 2 Very Minor Defect would be noticed by most discriminating customers. A portion of the product may have to be reworked on line but out of station 3 Minor Defect would be noticed by average customers. A portion of the product (<100%) may have to be reworked on line but out of station 4 Very Low Defect would be noticed by most customers. 100% of the product may have to be sorted and a portion (<100%) reworked 5 Low Comfort/convenience item(s) would be operable at a reduced level of performance. 100% of the product may have to be reworked 6 Moderate Comfort/convenience item(s) would be inoperable. A portion (<100%) of the product may have to be scrapped 7 High Product would be operable with reduced primary function. Product may have to be sorted and a portion (<100%) scrapped. 8 Very High Product would experience complete loss of primary function. 100% of the product may have to be scrapped 9 Hazardous Warning Failure would endanger machine or operator with a warning 10 Hazardous w/out Warning Failure would endanger machine or operator without a warning
- 30. 30 FMEA WORKSHEET Process or Product Name Change Oil in Car Prepared by: Leon Page _____ of ______ Person Responsible Leon Mechanic Date (Orig) __27 Sep 2007___ Revised __________ Process Step Key Process Input Potential Failure Mode Potential Failure Effect S e v Potential Causes O c c Current Controls D e t R P N Actions Recommended S e v O c c D e t R P N Fill with new oil New Oil— Mech anic Wrong type of oil Engine wear 2 No oil added Engine Failure 1 0 Sev - Severity of the failure (what impact will it have on our process?) Occ – How likely is the event to occur (probability of occurrence) Det – How likely can the event be detected in time to do something about it RPN – Risk Priority Number (multiply Sev, Occ, and Det)
- 31. 31 HOW TO COMPLETE A FMEA Step 5 For each potential failure mode identify one or more potential causes (Could use Affinity Diagram again to brainstorm ideas) Rate the probability of each potential cause occurring based on criteria table (next slide) Place the rating in the column labeled OCC (occurrence).
- 32. 32 FMEA OCCURRENCE (OCC RATING) OCC Occurrence Criteria 1 Remote 1 in 1,500,000 Very unlikely to occur 2 Low 1 in 150,000 3 Low 1 in 15,000 Unlikely to occur 4 Moderate 1 in 2,000 5 Moderate 1 in 400 Moderate chance to occur 6 Moderate 1 in 80 7 High 1 in 20 High probability that the event will occur 8 High 1 in 8 9 Very High 1 in 3 Almost certain to occur 10 Very High > 1 in 2
- 33. FMEA WORKSHEET Process or Product Name Change Oil in Car Prepared by: Leon Page _____ of ______ Person Responsible Leon Mechanic Date (Orig) __27 Sep 2007___ Revised __________ Process Step Key Process Input Potential Failure Mode Potential Failure Effect S e v Potential Causes O c c Current Controls D e t R P N Actions Recommended S e v O c c D e t R P N Fill with new oil New Oil— Mech anic Wrong type of oil Engine wear 2 Mis- labeled 3 No oil added Engine Failure 1 0 Hurrying 3 Sev - Severity of the failure (what impact will it have on our process?) Occ – How likely is the event to occur (probability of occurrence) Det – How likely can the event be detected in time to do something about it RPN – Risk Priority Number (multiply Sev, Occ, and Det)
- 34. 34 HOW TO COMPLETE THE FMEA Step 6 Identify current controls or detection Rate ability of each current control to prevent or detect the failure mode once it occurs using criteria table (next slide) Place rating in Det column
- 35. 35 FMEA DETECTION (DET) RATING DET Detection Criteria 1 Almost Certain Current Controls are almost certain to detect/prevent the failure mode 2 Very High Very high likelihood that current controls will detect/prevent the failure mode 3 High High Likelihood that current controls will detect/prevent the failure mode 4 Mod. High Moderately High likelihood that current controls will detect/prevent the failure mode 5 Moderate High Likelihood that current controls will detect/prevent the failure mode 6 Low Low likelihood that current controls will detect/prevent failure mode 7 Very Low Very Low likelihood that current controls will detect /prevent the failure mode 8 Remote Remote likelihood that current controls will detect/prevent the failure mode 9 Very Remote Very remote likelihood that current controls will detect/prevent the failure mode
- 36. FMEA WORKSHEET Process or Product Name Change Oil in Car Prepared by: Leon Page _____ of ______ Person Responsible Leon Mechanic Date (Orig) __27 Sep 2007___ Revised __________ Process Step Key Process Input Potential Failure Mode Potential Failure Effect S e v Potential Causes O c c Current Controls D e t RPN Actions Recommended S e v O c c D e t R P N Fill with new oil New Oil from supplier Wrong type of oil Engine wear 2 Misread oil chart for vehicle 3 None 9 No oil added Engine Failure 1 0 Hurrying 3 Engine light 3 Sev - Severity of the failure (what impact will it have on our process?) Occ – How likely is the event to occur (probability of occurrence) Det – How likely can the event be detected in time to do something about it RPN – Risk Priority Number (multiply Sev, Occ, and Det)
- 37. 37 HOW TO COMPLETE THE FMEA Step 7 Multiply SEV, OCC and DET ratings and place the value in the RPN (risk priority number) column. The largest RPN numbers should get the greatest focus. For those RPN numbers which warrant corrective action, recommended actions and the person responsible for implementation should be listed. SEV * OCC * DET = RPN ( 2 * 3 * 9 = 54 ) Process Step Key Process Input Potential Failure Mode Potential Failure Effect S e v Potential Causes O c c Current Controls D e t RPN Actions Recommended S e v O c c D e t R P N Fill with new oil New Oil from supplier Wrong type of oil Engine wear 2 Misread oil chart for vehicle 3 None 9 54 No oil added Engine Failure 1 0 Hurrying 3 Engine light 3 90
- 38. 38 FMEA RANKINGS Severity Occurrence Detection Hazardous without warning Very high and almost inevitable Cannot detect or detection with very low probability Loss of primary function High repeated failures Remote or low chance of detection Loss of secondary function Moderate failures Low detection probability Minor defect Occasional failures Moderate detection probability No effect Failure Unlikely Almost certain detection Rating 10 1 High Low Source: The Black Belt Memory Jogger, Six Sigma Academy
- 39. ACTION RESULTS Step 8 After corrective action has been taken, place summary of the results in the ‘Actions Recommended’ block Assign new value for: Severity Occurrence Detection Calculate new RPN number
- 40. FMEA WORKSHEET Process or Product Name Change Oil in Car Prepared by: Leon Page _____ of ______ Person Responsible Leon Mechanic Date (Orig) __27 Sep 2007___ Revised __________ Process Step Key Process Input Potential Failure Mode Potential Failure Effect S e v Potential Causes O c c Current Controls D e t RPN Actions Recommended S e v O c c D e t R P N Fill with new oil New Oil from supplier Wrong type of oil Engine wear 2 Misread oil chart for vehicle 3 None 9 54 No oil added Engine Failure 1 0 Hurrying 3 Engine light 3 90 Oil level checked by partner 1 0 3 1 3 0 Sev - Severity of the failure (what impact will it have on our process?) Occ – How likely is the event to occur (probability of occurrence) Det – How likely can the event be detected in time to do something about it RPN – Risk Priority Number (multiply Sev, Occ, and Det)
- 41. FMEA EXAMPLE Source: Quality Digest/ August 2006 Quality Service at the Special Olympics World Games, Tang Xiaofen Process or Product Name: Hotel Service at Special Olympics Prepared by: Page _____ of ______ Person Responsible: Joe Quality Date (Orig) ___________ Revised __________ Process Step Key Process Input Potential Failure Mode Potential Failure Effect S e v Potential Causes O c c Current Controls D e t R P N Actions Recommended S e v O c c D e t R P N Register guest Service Desk Cannot Register in time Complaints 5 Lack of language and communicat ion skills, support of volunteers not sufficient 4 No plan on training content; training and volunteer support sufficient 3 72 Provide Guest Services Guest Support Lack of barrier- free facility Inconvenien ce and injury 10 Cannot provide barrier-free facility 3 Providing barrier-free facility 7 210 Provide Meals Food Service Food goes bad Disease or injury 10 Past shelf life 6 No control of raw material 8 240 Provide Medical Service Medical Service Service not in time Illness changes for worse 10 No 24 Hour service 6 12 hour service 3 180