Published on

Published in: Business, Technology
  • Be the first to comment

No Downloads
Total views
On SlideShare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide


  1. 1. Design Failure Mode & Effect Analysis, Design Review & Design Validation Plan (DFMEA, DR & DVP) Dr K C Vora Deputy Director & Head, ARAI Academy, ARAI
  2. 2. New Product Development (NPD) Concept Phase Feasibility studies Formulate development policy Definition Phase Draft several scheduling proposals Design Phase General design Jigs, tools & equipment Make tradeoffs Define system specifications Solicit bids (when using subcontractors) Production process design Detailed design Make prototypes List operational requirements Production Phase Prototype testing Qualification testing Pilot production Pilot evaluation Full production startup Product launch Market stage
  4. 4. DFMEA
  5. 5. FMEA • FAILURE MODES & EFFECTS ANALYSIS (FMEA) is a paper-and-pencil analysis method used in engineering to document and explore ways that a product design might fail in real-world use. • Failure Mode & Effects Analysis is an advanced quality improvement tool. • FMEA is a technique used to identify, prioritize and eliminate potential failures from the system, design or process before they reach the customer. • It provides a discipline for documenting this analysis for future use and continuous process improvement.
  6. 6. History of FMEA • Historically, FMEA was one of the first systematic techniques for failure analysis developed by the U.S. Military on 9th November, 1949. FMEA was implemented in the 1960’s and refined in the 70’s. It was used by reliability engineers working in the aerospace industry. • Then the Automotive Industry Action Group formed by Chrsyler, Ford & GM restructured the FMEA techniques which found a lot of importance in the automotive industry. • Since then FMEA has been instrumental in producing quality goods in the automotive sector.
  7. 7. Types of FMEAs • Design –Analyzes product design before release to production, with a focus on product function. –Analyzes systems and subsystems in early concept and design stages. • Process –Used to analyze manufacturing and assembly processes after they are implemented.
  8. 8. Types of DFMEA • SYSTEM FMEA - Chassis system - Engine system - Transmission • COMPONENT FMEA - Piston - Crankshaft
  9. 9. FMEA Timeline DFMEA: Starts early in process. It is complete by the time preliminary drawings are done but before any tooling is initiated. PFMEA: Starts as soon as the basic manufacturing methods have been discussed. It is completed prior to finalizing production plans and releasing for production.
  10. 10. Standards MIL-STD 1629, “Procedures for Performing a Failure Mode and Effect Analysis” IEC 60812, “Procedures for Failure Mode and Effect Analysis (FMEA)” BS 5760-5, “Guide to failure modes, effects and criticality analysis (FMEA and FMECA)” SAE ARP 5580, “Recommended Failure Modes and Effects Analysis (FMEA) Practices for Non-Automobile Applications” SAE J1739, “Potential Failure Mode and Effects Analysis in Design (Design FMEA)” SEMATECH (1992,) “Failure Modes and Effects Analysis (FMEA): A Guide for Continuous Improvement for the Semiconductor Equipment Industry”
  11. 11. Limitations of FMEA • They can only be used to identify single failures and not combinations of failures • Failures which result from multiple simultaneous faults are not identified by this • Unless adequately controlled and focused, the studies can be time consuming • They can be difficult and tedious for complex multi-layered systems • They are not suitable for quantification of system reliability
  12. 12. Responsibility and scope of DFMEA • The DFMEA is a team function – All team members must participate – Multi-disciplinary expertise and input is beneficial • Input from all engineering fields is desirable • Representatives from all areas (not just technical disciplines) are generally included as team members • The DFMEA is not a one meeting activity – The DFMEA will be refined and evolve with the product – Numerous revisions are required to obtain the full benefit of the DFMEA • The DFMEA must include all systems, sub-systems and components in the product design
  13. 13. Steps to conduct DFMEA • Form the cross functional team. • Call FMEA Meeting with advance intimation. • Complete the top of the form – Project, year, team members, date, and DFMEA iteration – There will be many iterations • List items and functions – Start with the system, then subsystems and finally components • Document potential failure modes – How could the design potentially fail to meet the design intent? – Consider all types of failure • Document the potential effects of failure – How would design potentially fail to meet the design intent?
  14. 14. • • Rate the severity of the failure effect – See ranking guidelines – Severity ranking is linked to the effect of the failure Document potential causes and mechanisms of failure – Failure causes and mechanisms are an indication of design weaknesses – Potential failure modes are the consequences of the failure causes – A single failure mode may have multiple failure mechanisms – Use group brainstorming sessions to identify possible failure mechanisms – Don’t be afraid to identify as many potential causes as you can – This section of the DFMEA will help guide you in necessary design changes – The output of the DFMEA will indicate on which item to focus design efforts
  15. 15. • • Rate the occurrence – See attached page for ranking guidelines – Things that may help you rate the occurrence • Are any elements of the design related to a previous device or design? • How significant are the changes from a previous design? • Is the design entirely new? List the design controls – Design controls are intended to: • Prevent the cause of the failure mode (1st choice solution) • Detect the cause of the failure mode (2nd choice solution) • Detect the failure mode directly (3rd choice solution)
  16. 16. – Applicable design controls include • Predictive code analysis, simulation, and modeling • Tolerance “stack-up” studies • Prototype test results (acceptance tests, DOE’s, limit tests) • Proven designs, parts, and materials • List any critical or special characteristics – – • Critical characteristics: Severity > 8 and Occurrence >1 Special characteristics: Severity > 6 and Occurrence >2 Detection rate – • See attached page for ranking guidelines Calculate the RPN of each potential failure effect – – • RPN = (Severity) x (Occurrence) x (Detection) What are the highest RPN items? Define recommended actions – What tests and/or analysis can be used to better understand the problem to guide necessary design changes ?
  17. 17. • Assign action items – Assemble team – Partition work among different team members – Assign completion dates for action items – Agree on next team meeting date • Complete “Action Results” Section of DFMEA – Note any work not accomplished (and the justification for incomplete work) in the “actions taken” section of the DFMEA. • Why was nothing done?
  18. 18. – Change ratings if action results justify adjustment, but the rules are: • Severity: May only be reduced through elimination of the failure effect • Occurrence: May only be reduced through a design change • Detection: May only be reduced through improvement and additions in design control (i.e. a new detection method, better test methodology, better codes, etc.) – Include test and analysis results with DFMEA to validate changes.
  19. 19. __ System __ Subsystem __ Component Model Year/Vehicle(s): Core Team: Potential Failure Mode and Effects Analysis (Design FMEA) Design Responsibility Key Date: FMEA Number: Page 1 or 1 Prepared by: FMEA Date (Orig.): Responsibil Action Results Potential Current D O Current Potential Potential S C ity L Cause(s)/ C Design Design E R. Recommend Failure Effect(s) of & Target Actions S O D R. C T P. ed E AMechanism(s) U Controls Controls E N. P. Mode Failure S Action(s) Completion Taken E C E Of Failure R Prevention Detection C V C T N. VS Function Date Item 19
  20. 20. The FMEA Form Identify failure modes and their effects Identify causes of the failure modes and controls Prioritize Determine and assess actions
  21. 21. FMEA Sequence Subsystem Potential Potential S C Potential O Current Controls failure Effect(s) E L Cause(s) C mode of V A Mechanism C Failure S (s) of U S Failure R Function Requires What are the effect(s)? How bad is it? What are the Functions, Features or Requirements? What can go wrong? - No function - Partial/ over/ degraded function - Intermittent function - Unintended function What are the cause(s)? How often does it happen? How can this be prevented and detected? D R Recommen Respons E P ded ibility & T N Action(s) Target E completi C on date T I O N What can be done? - Design changes - Process changes - Special controls - Changes to standards, procedures, or guides How good is this method at detecting it? Action results Act- S O D R ion E C E . s V CT P take . n N .
  22. 22. FMEA Procedure List all Function & requirements List all conceivable failure modes Consider effects, if above failure mode happens Look possible causes & mechanism for failures mode Assess the frequency of occurrence of failure modes (O) Re- evaluate (New RPN ) Define Responsibility & Time- frame Recommend improvements Calculate the Risk Priority Number (RPN) Assess the possibility of Failure being detected ( D ) Assess the Severity of effect (s)
  23. 23. Functions & Requirements • • • • • Functional Requirements Customer Requirements Legal Requirements Benchmarking Requirements State of the Art Trend
  24. 24. Function & Function Tree Function means what the product does, and is normally considered in a dynamic sense, expressed as Verb + object - (There could be a number of functions for a product or its sub assy. Or part.) Example – • Can drive with stability, • Generates electricity, • Propels airplane, • Some time cd be given as static expression by noun + adjective– • Easy handling, good look, quite sound, • Also expressed as adverb – • Rotate smoothly • Basic functions are expressed by verb + Object
  25. 25. Motivation • Analyze the vehicle / engine / system / components and summarize various functions and failure modes. • Conduct DFMEA various components/systems. •These components & systems all had failure modes and a corresponding Risk Priority Number (RPN) to be calculated using severity, occurrence & detection rankings. •The idea is to reduce this RPN value so that the components/systems are designed more towards reliability and safety. These reductions are to be done through design changes.
  26. 26. Famous Failures
  27. 27. Failure Definitions Failure: (Noun)  1a- Omission of occurrence or performance, specifically a failing to perform a duty or expected action  1b- A state of inability to perform a normal function  1c- A fracturing or giving away under stress  2.- A lack of success  3.- A falling short or deficiency  Deterioration or decay
  28. 28. Failure Definitions Fail: (Noun) (a)  To lose strength: Weaken  To fade or die away  To stop functioning  To fall short  To be absent or inadequate  To be unsuccessful ( b)  To miss performing an expected service or function  To be deficient in: Lack  To leave undone: Neglect  To be unsuccessful in passing (like a test)
  29. 29. Failure Categories Failure Categories • • • • • • • Reliability Catastrophic Complete Critical Degradation Dependent Gradual • Independent • • Inherent • Weakness • • Intermittent • • Major • • Minor • • Misuse • • Non-relevant Partial Primary Random Relevant Secondary Sudden Wear-out
  30. 30. How We Call a Failure ? 1. Unsuccessful (Not meeting design intent) 2. Deteriorating (Not to standards) 3. Defective (Imperfection, flaw) 4. Decaying (Gradual or sudden decline) 5. Deficient (Impaired or inferior; weak) 6. Incomplete (Inadequate) 7. Non-Functional (Doesn’t work) 8. Omission (Overlooked, neglected, missed)
  31. 31. Examples  Unsuccessful: A required function is wrong Example: Wrong firing sequence in engine  Deteriorating: A measured value does not meet an established level Example: Engine power does not qualify to a defined level Defective: A part has a physical flaw Example: Crack in the engine casting Decaying: A measured value has changed from an initial baseline level Example: Head lamp light lux level reduction over time  
  32. 32. Examples  Deficient: A material or product is not capable of meeting requirements Example: Strength of con-rod deficient due to selected material grade. Incomplete: One or more expected functions or outputs are missing Example: Kombi –switch does not provide for night light dipping. (not considered by development) Non-Functional: The component is not working or responding to commands Example: Kombi –switch does not function for command for night light dipping ( considered in dev, but not performing ) Omission: A required characteristic has not been designed or measured Example: Water pressure in radiator not considered in design
  33. 33. Failures & Failure Modes Failures modes – • Concept of failure mode is fundamental to FMEA • A failure mode is not a failure in itself, it is a class of undesirable phenomena that can result in failure. • Failure mode is also not a actual cause of failure. • Wire break, short circuit, adhesion, surface roughness, leakage, detachment, slackness, blockage, deformation, snapping, cracking, loss are few examples of failure mode. CAUSE Cause of failure mode FAILURE-MODE FAILURE Effect of failure mode
  34. 34. Failures & Failure Modes CAUSE CAUSE • Wrong oil selection • Wrong gasket • wrong workmanship • Over filling • Wrong breather • Deflection Leakage ( Oil / Gas ) Oil leakage FAILURE • FAIURES • Engine stalling • Over Heating • Air entrapping • Others
  35. 35. Severity, Occurrence & Detection • Severity – Importance of the effect on customer requirements • Occurrence – Frequency with which a given cause occurs and creates failure modes • Detection – The ability of the current control scheme to detect or prevent a given cause 35
  36. 36. Occurrence (O) Table Probability of Failure Very High : Persistent failures Possible Failure Rates > 100 per thousand vehicles/ items 50per thousand vehicles/ items Ranking 10 9 High : Frequent failures 20 per thousand vehicles/ items 8 10 per thousand vehicles/ items 7 5 per thousand vehicles/ items 6 2 per thousand vehicles/ items 5 1 per thousand vehicles/ items 4 Low : Relatively few failures 0.5 per thousand vehicles/ items 3 0.1 per thousand vehicles/ items 2 Remote : Failure is unlikely < 0.010 per thousand vehicles/ items 1 Moderate : Occasional failures
  37. 37. Severity (S) Table Effect Hazardous without warning Criteria : severity of Effect Ranking Very high severity ranking when a potential failure mode affects safe 10 vehicle operation and/or involves noncompliance with government regulation without warning. Hazardous with warning Very high severity ranking when a potential failure mode affects safe vehicle operation and/or involves noncompliance with government regulation with warning. 9 Very High High Vehicle/ item inoperable (loss of primary function). Vehicle/ item operable but at reduced level of performance. Customer very dissatisfied. 8 7 Moderate Vehicle/ item operable, but Comfort/ Convenience item(s) inoperable. Customer dissatisfied. 6 Low Vehicle/ item operable, but Comfort/ convenience item(s) operable at a reduced level of performance. Customer somewhat dissatisfied. 5 Very Low Fit & Finish/ Squeak & Rattle item does not conform. Defect noticed by most customers (greater than 75%). 4 Minor Fit & Finish/ Squeak & Rattle item does not conform. Defect noticed by 50% of customers. 3 Very Minor Fit & Finish/ Squeak & rattle item does not conform. Defect noticed by discriminating customer (less than 25%). 2 None No discernible effect. 1
  38. 38. Detection (D) Table Detection Absolute Uncertainty Very Remote Remote Very Low Low Moderate Moderate High High Very High Almost Certain Criteria : Likelihood of Detection by Design Control Design control will not and/or can not detect a potential cause/ mechanism an subsequent failure mode; or there is no Design control Very remote chance the Design control will detect a potential cause/ mechanism and subsequent failure mode. Remote chance the Design control will detect a potential cause/ mechanism and subsequent failure mode. Very low chance the Design control will detect a potential cause/ mechanism and subsequent failure mode. Low chance the Design control will detect a potential cause/ mechanism and subsequent failure mode. Moderate chance the Design control will detect a potential cause/ mechanism and subsequent failure mode. Moderate high chance the Design control will detect a potential cause/ mechanism and subsequent failure mode. High chance the Design control will detect a potential cause/ mechanism and subsequent failure mode. Very high chance the Design control will detect a potential cause/ mechanism and subsequent failure mode. Design control will almost certainly detect a potential cause/ mechanism an subsequent failure mode. Ranking 10 9 8 7 6 5 4 3 2 1
  39. 39. Risk Priority Number (RPN)  RPN is the product of the severity, occurrence, and detection scores. Severity X Occurrence X Detection = RPN
  40. 40. RPN / Risk Priority Number Top 20% of Failure Modes by RPN R P N Failure Modes
  41. 41. Example of Significant / Critical Threshold Special Characteristics Matrix S E V E R I T Y POTENTIAL CRITICAL 10 CHARACTERISTICS Safety/Regulatory 9 8 POTENTIAL SIGNIFICANT 7 CHARACTERISTICS 6 Customer Dissatisfaction 5 4 ANOYANCE ALL OTHER ZONE 3 CHARACTERISTICS 2 Appropriate actions / 1 controls already in place 1 2 3 4 5 6 7 8 9 10 OCCURRENCE
  42. 42. FMEA Inputs and Outputs Inputs a Brainstorming Process Map Process History Procedures Knowledge Experience Outputs FMEA List of actions to prevent causes or detect failure modes History of actions taken
  43. 43. Action • Recommend Action, wherever RPN is high through - Design Controls - Design changes - Process changes - Special controls changes to standards/procedures/guidelines • Decide Responsibilities • Decide Target date of completion.
  44. 44. What Next? Repeat: undertake the next revision of the DFMEA The DFMEA is an evolving document! Revise the DFMEA frequently & keep on reducing RPN! Diligence will eliminate design risk! Include documentation of your results!
  45. 45. Design Review (DR)
  47. 47. DR Phase Planning
  48. 48. Participants for Design Review Design Engineer; System Engineer, System Experts, Process Engineer; Product Planner, Manufacturing Engineer, Sourcing Engineer; Reliability Engineer; Service Engineer; Contribution by Participants: Participants should come to the meeting along with the data worked out and results relevant to their roles/expertise required under "preparation list" and leading to "deliverables ".
  49. 49. Preparation for Design Review • • • • • • • • • • • • • • • Intent & concept definition of project Application details & translated to Technical requirements Design Inputs Customer Requirements - VOC; RWUP translated to technical requirements Deliverables- performance & endurance; Reliability goals Benchmark & competition data Information of failures /successes of similar products, competitor product Metallurgical data Cost data Design calculations of performance, endurance, strength requirements of system/ components Homologation requirements Legal regulation Layout & detail drawings of system Operational ergonomic requirement data Assembly build variation analysis.
  50. 50. Deliverables of Design Review Conformance of design to the intent & concept for performance, endurance & warranty. Conformance of design to strength Conformance to regulations & homologation Manufacturability aspects Serviceability aspects Identification of special/ stranger technology Use of standard products Use of standard materials Identification of patent issues- a) use of present- legal matters; b) patentable features Identification of overlapping & interdependent areas between Interfacing systems Identification of environmental issues Operational ergonomic conformance.
  51. 51. Design Validation Plan (DVP)
  52. 52. Design Validation Plan (DVP) • Design Validation is next step to DFMEA. • Depending upon RPN in DFMEA, the components are arranged in DVP. • It contains all the information regarding the acceptance criteria, responsible person or team, type of test and start & finish dates.
  53. 53. Why Design Validation? • ‘Are we building it right?’ • Major costs of projects are incurred in early design stages. • The cost of fixing a design and faulty decisions at later stages is exponentially greater than at an earlier stage. • Early Validation/Verification: reduces risk early in the program provides feedback to designers before delivery proves that requirements are met saves costs reduces complexity of fault detection
  54. 54. Validation Definition The documented act of proving that any procedure, process, equipment, material, activity or system, actually leads to the expected results. Design Validation means establishing by objective evidence that device specifications conform to user needs and intended uses.
  55. 55. Design, Build & Verify 55
  56. 56. Design Verification Catalogue (DVC) The Design Verification Catalogue (DVC) allows the System Engineers to verify that the vehicle / system / sub-system / component meets the design specifications appearing in corresponding VDS / SDS / CDS. • DVC serves to, describe appropriate Design Verification Methods (DVM) associate one or more verification methods with each SDS requirement capture facility and prototype requirements to conduct planned verifications. DVC includes the operating conditions, accuracy and uncertainty of the test. 56
  57. 57. Requirements of Design Validation • Design validation shall be performed under defined operating conditions on initial production units, lots or batches, or their equivalents. • It includes testing of production units under actual or simulated use conditions. • It includes software validation and risk analysis. • The Validation must be documented in Design Validation Plan.
  58. 58. Design Validation Process • Validation Plan • Validation Review • Validation Methods • Validation Report
  59. 59. Comparison Between Validation, Verification & Review
  60. 60. Validation Methods • Testing ( Static as well as Dynamic) • Analysis ( Using software's and simulations) • Inspection Methods(Visual or with Test Rigs) • Compilation of relevant scientific literature • Study of historical evidences of similar design
  61. 61. Examples of validation methods & activities • • • • • • Worst case analysis of an assembly. Fault tree analysis of a process or design. Failure modes and effects analysis (FMEA). Package integrity tests. Testing of materials. Comparison of a design to previous vehicles having an established history of successful use.
  62. 62. Conclusion For design of high performance products / systems / components, quality tools like DFMEA plays an important role to achieve desirable performance and durability requirements. If this is done right from concept stage, the risk of failures substantially reduces and lot of time, energy and cost is saved. Design Review is a continuous process of conforming that the design to the intent & concept for performance, endurance & warranty is foolproof. Design Validation Plan is a systematic plan to confirm that the design meets the desired target after verification.