Introduction to FMEA/FMECA


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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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Introduction to FMEA/FMECA

  1. 1. Michael Herman August 31, 2013 Introduction to FMEA/FMECA
  2. 2. 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/
  3. 3. Acronyms • FMECA - Failure Mode, Effects, and Criticality Analysis. • FMEA - Failure Mode and Effects Analysis. • CIL – Critical Items/Issues List Introduction to FMEA/ 3
  4. 4. 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). 4 Introduction to FMEA/FMECA
  5. 5. 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. 5 Introduction to FMEA/FMECA
  6. 6. 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. 6 Introduction to FMEA/FMECA
  7. 7. 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. Introduction to FMEA/FMECA7
  8. 8. 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) 8 Introduction to FMEA/FMECA
  9. 9. 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/
  10. 10. 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. 10 Introduction to FMEA/FMECA
  11. 11. 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, Enviro nmental, 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 11 Introduction to FMEA/FMECA
  12. 12. Conceptual Validation Engineering Development Engineering Prototype Production / 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 12 Introduction to FMEA/FMECA
  13. 13. • 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 13 Introduction to FMEA/FMECA
  14. 14. 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. 14 Introduction to FMEA/FMECA
  15. 15. The FMECA Analysis Process 1. Define the system 2. Define ground rules and assumptions 3. Construct system block diagrams 4. Identify failure modes 5. Analyze failure effects / causes 6. Feed results back into design process 7. Classify failure effects by severity 8. Perform criticality calculations 9. Rank failure mode criticality 10. Determine critical items 11. Feed results back into design process 12. Identify means of failure detection, isolation and compensating provisions 13. Document the analysis. Summarize uncorrectable design areas, identify special controls necessary to mitigate risk. 14. Make recommendations 15. Follow up on corrective action implementation / effectiveness click here for more information Introduction to FMEA/FMECA15