FMEA University of Ljubljana

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Bernhard Huber Ljubljana,management applied informatics Spring 2005. List of tables III,List of figures III,1 Introduction 1. 2 Definitions 2, 2 1 What is FMEA Failure Modes and Effects Analysis 2. 2 2 What is FMECA Failure Modes Effects and Criticality Analysis 3. 2 3 Background Information 3,3 Theoretical Approach 4. 3 1 Types of FMEA s 4,3 2 FMEA Timing 5,3 3 FMEA usage 6.
3 4 FMEA Procedure 7,3 4 1 Preparation 8,3 4 2 Describing the product or process 8. 3 4 3 Creating a Block Diagram 8,3 4 4 Header of the FMEA Form worksheet 9. 3 4 5 Severity 11,3 4 6 Causes of failure mode 12,3 4 7 Occurrence 12. 3 4 8 Detection 13,3 4 9 Risk Priority Numbers RPN 15. 3 4 10 Actions 15,4 Case Study with axiomatic approach 16.
4 1 FMEA AND AD 16,4 2 Step one 17,Bernhard Huber Ljubljana. management applied informatics Spring 2005,4 3 Step two 19. 4 4 Real case sliding door FIAT 22,5 Conclusion 26. Bibliography 28,Appendix A,Definition of FMECA terms A. List of tables,table 3 1 FMEA types 5,table 3 2 Example FMEA for ball point pen 10.
table 3 3 Severity Ranking and suggested criteria 12. table 3 4 Occurrence ranking and suggested criteria 13. table 3 5 Detection ranking and suggested criteria 14. table 4 1 linkage of the Relationship FR and DP 19. table 4 2 definition of terms for the RF formula 20. table 4 3 second level FR s 25,table 4 4 second level DP s 25. table 4 5 List of less reliable components 26,List of figures. figure 3 1 FMEA Process 7, figure 3 2 Example for a Block Diagram Car radio 9. figure 3 3 Example on an FMEA worksheet header 9,figure 4 1 Scheme of the approach 17. figure 4 2 matrix of the Functional Requirements 18. Bernhard Huber Ljubljana,management applied informatics Spring 2005.
figure 4 3 Relationship between FR and DP 18,figure 4 4 FR s and DP s process mapping 19. figure 4 5 Reliability Functionality 20, figure 4 6 Reliability Functionality for a two level system 21. figure 4 7 Document necessary to calculate RPNe 21. figure 4 8 Sliding door 22, figure 4 9 Functional and physical tree of the sliding door 23. figure 4 10 Correlation Matrix of the sliding door 24. Bernhard Huber Ljubljana,management applied informatics Spring 2005. 1 Introduction, During the last decades customers changed their buying behavior After World.
War II the customer demand was very high and unsatisfied Suppliers were. producing only necessary goods and in restricted quantities During the time. transaction between customer and suppliers took place The transaction from the. typical sellers market too the buyers market was the result. Globalization and World Wide Web are keywords for the society nowadays. Due to the fact that time and distance are becoming relative customers are placing. increased demands on high quality and reliable products Therefore manufacturers. invest a lot of time and money to increase quality But the increasing capabilities and. functionality of many products are making it more difficult for manufacturers to. maintain the quality and reliability, Traditionally reliability has been achieved through extensive testing and use. of techniques such as probabilistic reliability modeling These are techniques done in. the late stages of development The challenge is to design in quality and reliability. early in the development cycle, Therefore engineers introduced Failure Modes and Effects Analysis FMEA. FMEA is a methodology for analyzing potential reliability problems early in the. development cycle where it is easier to take actions to overcome these issues. thereby enhancing reliability through design FMEA is used to identify potential failure. modes determine their effect on the operation of the product and identify actions to. mitigate the failures A crucial step is anticipating what might go wrong with a. product While anticipating every failure mode is not possible the development team. should formulate as extensive a list of potential failure modes as possible 1. The early and consistent use of FMEA in the design process allows the. engineer to design out failures and produce reliable safe and customer pleasing. products FMEA does also capture historical information for use in future product. improvement, Crow Kenneth 2002 Failure Modes and Effects Analysis FMEA Online URL http www npd. solutions com fmea html 28 04 2005,Bernhard Huber Ljubljana. management applied informatics Spring 2005,2 Definitions.
To gain a better comprehension we should define some terms in the following. pages Therefore we start with the definition of FMEA and FMECA. 2 1 What is FMEA Failure Modes and Effects Analysis. Let us take a look into the World Wide Web there we can find several. definitions of FMEA The National Aeronautics and Space Administration NASA 2. define FMEA as a forward logic bottom up tabular technique that explores the. ways or modes in which each system element can fail and assesses the. consequences of each of these failures For them FMEA is a useful tool for cost and. benefit studies to implement effective risk mitigation and countermeasure It is also a. precursor to a fault tree analysis FTA, For Wikipedia3 the free online encyclopedia Failure Mode and Effect Analysis. is a method that examines potential product or process failures evaluates risk. priorities and helps determine remedial actions to avoid identified problems It is an. integral part of any ISO 9000 compliant quality system. Also the American Society for Quality4 has his own approach to Failure Mode. Effects Analysis For them it is a procedure in which each potential failure mode in. every sub item of an item is analyzed to determine its effect on other sub items and. on the required function of the item, All these definitions have some terms in common There is always a system. and an examination of potential failures After that follows an assessment of the. identified failures, NASA online URL http pbma hq nasa gov mainframe docs Hardware Design 4 3 4 5 htm. 28 04 2005, Wikipedia 2005 FMEA online URL http en wikipedia org wiki FMEA 30 04 2005. American Society for Quality FMEA online URL http www asq org info glossary f html. 28 04 2005,Bernhard Huber Ljubljana,management applied informatics Spring 2005.
2 2 What is FMECA Failure Modes Effects and Criticality. The next step in the FMEA evolution was FMECA FMECA is an acronym for. Failure Modes and Effects Criticality Analysis The American Society for Quality5. define it as a procedure that is performed after a failure mode effects analysis to. classify each potential failure effect according to its severity and probability of. occurrence,2 3 Background Information, The FMEA process was originally developed by the US military in 1949 to. classify failures according to their impact on mission success and. personnel equipment safety FMEA has since been used on the 1960s Apollo space. missions Also large Motor Companies like Ford used FMEA in the 1980s The aim. was to reduce risks after one model of car the Pinto suffered a fault in several. vehicles causing the fuel tank to rupture and it to subsequently burst into flames after. FMECA has been developed by NASA and several useful databases of failure. rates and failure modes have been compiled by the Reliability Analysis Center. RAC a U S Department of Defense Information Analysis Center One important. Report is the Failure Mode Effects and Criticality Analysis FMECA Report Number. F30602 91 C 0002 from the RAC 7, Various industries have their own Failure Mode and Effects Analysis. standards Aerospace and defense companies generally use either the MIL STD. 1629A FMECA standard failure mode effect and criticality analysis or the SAE. ARP5580 FMEA standard Automotive suppliers use SAE J1739 FMEA s or they. may use the Automotive Industry Action Group AIAG FMEA Daimler Chrysler. American Society for Quality FMECA online URL http www asq org info glossary f html. 28 04 2005, Wikipedia 2005 FMEA online URL http en wikipedia org wiki FMEA 30 04 2005. Predictive Maintenance Corporation 2004 FMECA Introduction online URL. http www pmaint com EFMECA html 10 05 2005,Bernhard Huber Ljubljana. management applied informatics Spring 2005, Ford or GM FMEA methodologies Other industries generally adopt one of these.
FMEA standards or others such as IEC 60812 or BS 5760 sometimes customizing. them to meet their own requirements 8,3 Theoretical Approach. After the theoretical definitions about FMEA and FMECA in the chapter before. we have to distinguish between different types of FMEA s and the usage of FMEA. But the main part of the following chapter discussed the FMEA process. But first let as take a look on one further standard The IEEE Standard 352. 1975 is the IEEE Guide for General Principles of Reliability Analysis of Nuclear. Power Generating Station Protection Systems There they define the purposes of an. FMEA as being to assist in selecting design alternatives with high reliability and high. safety potential during early design phase and ensure that all conceivable failure. modes and their effects on operational success of the system have been considered. The next step should be to list potential failures and identify the magnitude of their. effects Then to develop early criteria s for test planning and the design of the test. and check out systems The FMEA can then provide a basis for quantitative reliability. and availability analyses and also provide historical documentation for future. reference to aid in analysis of field failures and consideration of design changes It. can also provide input data for trade off studies and provide basis for establishing. corrective action priorities FMEA assist in the objective evaluation of design. requirements related to redundancy failure detection systems fail safe. characteristics and automatic and manual override 9. 3 1 Types of FMEA s, There are several types of FMEA s Some o them are used much more often. than others FMEA s should always be done whenever failures would mean potential. Relex Software 2005 FMEA FMECA online URL, http www relexsoftware com products fmeafmeca asp 10 05 2005. Guide for General Principles of Reliability Analysis of Nuclear Power Generating Station Protection. Systems IEEE Std 352 1975,Bernhard Huber Ljubljana. management applied informatics Spring 2005, harm or injury to the user of the end item being designed The different types of FEA.
can be seen in table 3 1,FMEA types usage,System focuses on global system functions. Design or Construction focuses on components and subsystems. Process focuses on manufacturing and assembly processes. Service focuses on service functions,Software focuses on software functions. table 3 1 FMEA types,3 2 FMEA Timing, What is the right timing for FMEA Failure Modes and Effects Analysis is a. living document Throughout the product development cycle change and updates are. made to the product and process As a matter of fact these changes can and often. do introduce new failure modes And so it is therefore important to review and update. the FMEA in special cases like when a new product or process is being initiated at. the beginning of the cycle or changes are made to the operating conditions the. product or process is expected to function in Next possible reason for changing the. FMEA is when a change is made to either the product or process design The. product and process are inter related that means when the product design is. changed the process is impacted and vice versa Two further reasons are new. regulations are instituted and last but not least customer feedback indicates problems. in the product or process 10, It is also possible to perform an FMEA with limited design information But in. this case the basic questions should be answered by the FMEA These questions. How can each part conceivably fail, What mechanisms might produce these modes of failure.
What could the effects be if these failures did occur. Is the failure in the safe or unsafe direction, Crow Kenneth 2002 Failure Modes and Effects Analysis FMEA Online URL http www npd. solutions com fmea html 18 05 2005,Bernhard Huber Ljubljana. management applied informatics Spring 2005,How is the failure detected. What inherent provisions are provided in the design to compensate for. the failure,3 3 FMEA usage, When do we use FMEA In the past engineers have done a good job of. evaluating the functions and the form of products and processes in the design phase. But the designing in reliability and quality was a huge problem Often the engineer. uses safety factors as a way of making sure that the design will work and protected. the user against product or process failure As described in an article from the. Mechanical Engineering, A large safety factor does not necessarily translate into a.
reliable product Instead it often leads to an over designed. product with reliability problems 11, With FMEA the engineer get a tool with can assist in providing reliable safe. and customer pleasing products and processes FMEA helps the engineer to identify. potential product or process failures, FMEA can be used to develop product or process requirements that minimize. the likelihood of those failures FMEA is also the basis for. Evaluate the requirements obtained from the customer or other participants in. Therefore we start with the definition of FMEA and FMECA 2 1 What is FMEA Failure Modes and Effects Analysis Let us take a look into the World Wide Web there we can find several definitions of FMEA The National Aeronautics and Space Administration NASA 2 define FMEA as a forward logic bottom up tabular technique that explores the ways or modes in which each system element can fail

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