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This presentation provides a nice introduction to Failure Mode, Effects and Criticality Analysis (FMECA). Includes history and background, definitions, timelines for implementing and describes the FMEA methodology.
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Michael Herman
August 31, 2013
Introduction to FMEA/FMECA
http://www.fmea-fmeca.com
FMEA and FMECA
• What is it?– A systematic analysis technique which
facilitates the identification of potential problems by examining the effects of lower level failure modes on system operation.
2 Introduction to FMEA/FMECAwww.fmea-fmeca.com
Acronyms
• FMECA - Failure Mode, Effects, and Criticality Analysis.
• FMEA - Failure Mode and Effects Analysis.• CIL – Critical Items/Issues List
Introduction to FMEA/FMECAwww.fmea-fmeca.com 3
Why is FMEA / FMECA Important?• Provides a basis for identifying root failure causes
and developing effective corrective actions• Identifies reliability/safety critical components• Facilitates investigation of design alternatives at all
stages of the design• Provides a foundation for maintainability, safety,
testability, and logistics analyses• FMECA and CIL (Critical Items List) evaluations
cross check the completeness of the safety hazard analysis.
• Serves as a formal record of the analysis performed. Could be used as evidence in court (e.g. product safety).
www.fmea-fmeca.com 4 Introduction to FMEA/FMECA
Background / History• Originally part of risk management techniques
developed for defense and nuclear industries in the 1940’s.
• An offshoot of Military Procedure MIL-P-1629, titled Procedures for Performing a Failure Mode, Effects and Criticality Analysis, dated November 9, 1949.
• Used as a reliability evaluation technique to determine the effect of system and equipment failures. Failures were classified according to their impact on mission success and personnel/equipment safety.
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Background / History• Formally developed and applied by NASA in the
1960’s to improve and verify reliability of space program hardware.
• Early adopters were the aerospace, petroleum, chemical, and automotive industries.
• In the 1990’s the medical devices industry began using FMECA in response to new FDA regulations / guidelines.
fmea-fmeca.com 6 Introduction to FMEA/FMECA
FMECA Standards/Guidelines• The procedures called out in MIL-STD-1629A are
probably the most widely accepted methods throughout the military and commercial industry.
• SAE J-1739 is a prevalent FMEA standard in the automotive industry.
• SAE ARP5580 - FMECA for Non-Automotive applications. Provides some upgrades to MIL-STD-1629A.
• Army TM 5-698-4 – FMECA for C4ISR Facilities• MIL-STD-882D – Helpful in assessing safety issues
and identifying critical items.
fmea-fmeca.com Introduction to FMEA/FMECA7
Definitions• Failure Cause: The physical or chemical processes,
design defects, quality defects, part misapplication or other processes which are the basic reason for failure or which can initiate the physical process by which deterioration proceeds to failure. Why does it fail? (Past)
• Failure Mode: The way in which a failure is observed, describes the way the failure occurs, and its impact on equipment operation. How does it fail? (Present)
• Failure Effect: The consequence a failure mode has upon the operation, function or status of a system or equipment. What happens when it fails? (Future)
fmea-fmeca.com 8 Introduction to FMEA/FMECA
Definitions
• Local Effect: The consequence a failure mode has on the operation, function or status of the specific item being analyzed.
• Next Higher Effect: The consequence a failure mode has upon the operation, function, or status at the next higher level of assembly.
• End Effect: The consequence a failure mode has upon the operation, function, or status at the highest level of indenture. Sometimes referred to as a System Effect.
Types of Failure Effects:
Introduction to FMEA/FMECA9fmea-fmeca.com
Definitions• Severity: Considers the worst possible consequence of a
failure classified by the degree of injury, property damage, system damage and mission loss that could occur.
• Criticality: A relative measure of the consequences of a failure mode and its frequency of occurrence.
• Failure Mode Ratio: The probability of occurrence of a failure mode. The sum of the failure mode ratios for an item should equal 1.0. Sometimes referred to as alpha (α).
• Failure Effect Probability: Often referred to as the End Effect Conditional Probability or beta (β). Represents the probability that a particular failure effect will result, given that a certain failure mode occurs.
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Types of FMEA/FMECA• There are many different flavors or types of FMECA.• Both qualitative and quantitative approaches may be
used.• Some examples are: Concept, Design, Process,
Hardware, Functional, Software, Interface, Healthcare, Machinery, Environmental, etc…
• The technique is basically the same when completing each type of FMECA, but the criteria used in determining failure modes, effects, severity levels and other aspects of the FMECA may be tailored for each specific use.
www.fmea-fmeca.com 11 Introduction to FMEA/FMECA
Conceptual ValidationEngineering Development
Engineering PrototypeProduction / Deployment
Design Process
FMECA
Design Reviews
ACQUISITION PROGRAM
Functional HardwareUpdates Updates
PDR CDR PRDR FACI
PDR - Preliminary Design Review CDR - Critical Design Review PRDR - Preproduction Design Review FACI - First Article Configuration Inspection
FMECA Timeline – Aerospace Industry
www.fmea-fmeca.com 12 Introduction to FMEA/FMECA
• Design FMECA– Start early in process. Complete by the time preliminary drawings are done, but
before any tooling is initiated.
• Process FMECA– Start as soon as basic manufacturing methods have been discussed. Complete prior
to finalizing production plans and releasing for production
Concept Prototype Build
Design Go-Ahead
Production Start
Eng./Mfg. Sign Off
Design Completion
Design FMEA Process FMEA
FMECA Timeline – Automotive Industry
www.fmea-fmeca.com 13 Introduction to FMEA/FMECA
How is FMECA Done?Bottom-Up Analysis Top-Down Analysis
Determine failure modes of lower level items.
Work upward and determine effects.
Pick upper level failure modes.
Work downward and flow down causes.
www.fmea-fmeca.com 14 Introduction to FMEA/FMECA
The FMECA Analysis Process1. Define the system2. Define ground rules and assumptions3. Construct system block diagrams4. Identify failure modes5. Analyze failure effects / causes6. Feed results back into design process7. Classify failure effects by severity8. Perform criticality calculations9. Rank failure mode criticality10. Determine critical items11. Feed results back into design process12. Identify means of failure detection, isolation and compensating provisions13. Document the analysis. Summarize uncorrectable design areas, identify special
controls necessary to mitigate risk.14. Make recommendations15. Follow up on corrective action implementation / effectiveness
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