Potential Failure Mode and Effects

Chrysler Corporation, Ford Motors, General Motors Corporation 1995 Potential Failure Mode and Effects Analysis (FMEA) - Reference Manual, 2nd Edition. 

Potential failure mode and effects analysis (FMEA) (GM, Ford, Chrysler)... 

If you need a nnore granular or finely tuned approach for your severity and occurrence ratings, see Potential Failure Mode and Effects Analysis (2001), available from the Automotive Industry Action Croup at AIAC.org. 

Automotive Industry Action Group (AIAG) (1995b), Potential Failure Mode and Effects Analysis Reference Manual, 2nd Ed., AIAG, Detroit. 

Suppliers to those auto companies must meet the requirements set forth in a reference manual titled Potential Failure Mode and Effects Analysis—FMEA and must do what the title implies. They make failure mode and effects analyses of the equipment they supply. In that process, a risk priority number (RPN) is developed, giving consideration to occurrence likelihood, severity of effect, and detection ability. 

Potential Failure Mode and Effects Analysis in Design (Design FMEA) and Potential Failure Mode and Effects Analysis in Manufacturing and assembly Processes (Process FMEA) Reference Manual. Society of Automotive Engineers, 2000. 

Automobile Industry FMEAs DaimlerChrysler, Ford, and General Motors are represented in the Automotive Industry Action Group (AIAG). FMEA teams in those companies, working under the auspices of the Automotive Division of the American Society for Quality (ASQC) and AIAG, developed a reference manual titled Potential Failure Mode and Effects Analysis FMEA, currently in its third edition. Excerpts from the manual are reprinted here with permission from the FMEA Manual (DaimlerChrysler, Ford, General Motors Supplier Quality Requirements Task Force). 

SAE J1739 Potential failure mode and effects analysis in design (design FMEA) and potential failure mode and effects analysis in manufacturing and assembly processes (process FMEA) and effects analysis for machinery (machinery FMEA) ... 

The original standard for FMEA is MIL-STD-1629A, Procedures for Performing a Failure Mode, Effects and Criticality Analysis, 1980. A more recent standard is SAE/ARP-5580, Recommended FMEA Practices for Non-Automobile Applications, July 2001. Another more recent standard is SAE Standard J-1739, Potential Failure Mode and Effects Analysis in Design (Design FMEA) and Potential Failure Mode and Effects Analysis in Manufacturing and Assembly Processes (Process FMEA) and Effects Analysis for Machinery (Machinery FMEA), August 2002. 

Failure Mode and Effects Analysis. The system design activity usually emphasizes the attainment of performance objectives in a timely and cost-efficient fashion. The failure mode and effects analysis (FMEA) procedure considers the system from a failure point of view to determine how the product might fail. The terms design failure mode and effects analysis (DFMEA) and failure mode effects and criticaUty analysis (EMECA) also are used. This EMEA technique is used to identify and eliminate potential failure modes early in the design cycle, and its success is well documented (3,4). 

The EMEA begins with the selection of a subsystem or component and then documents all potential failure modes. Their effect is traced up to the system level. A documented worksheet similar to Eigure 4 is used on which the following elements are recorded. 

The cost of performing the hazard identification step depends on the size of the problem and the specific techniques used. Techniques such as brainstorming, what-if analyses, or checklists tend to be less expensive than other more structured methods. Hazard and operability (HAZOP) analyses and failure modes and effects analyses (FMEAs) involve many people and tend to be more expensive. But, you can have greater confidence in the exhaustiveness of HAZOP and FMEA techniques—their rigorous approach helps ensure completeness. However, no technique can guarantee that all hazards or potential accidents have been identified. Figure 8 is an example of the hazards identified in a HAZOP study. Hazard identification can require from 10% to 25% of the total effort in a QRA study. 

There is one technique widely used in the automotive industry for detecting and analyzing potential nonconformities Failure Modes and Effects Analysis (FMEA). There are Design FMEAs and Process FMEAs. The technique is the same - it is only the focus that is different. As clause 4.14 addresses potential nonconformities, the subject of FMEAs is treated in Part 2 Chapter 14. 

A failure modes and effects analysis is a systematic analytical technique for identifying potential failures in a design or a process, assessing the probability of occurrence and likely effect, and determining the measures needed to eliminate, contain, or control the effects. Action taken on the basis of an FMEA will improve safety, performance, reliability, maintainability and reduce costs. The outputs are essential to balanced and effective quality plans for both development and production as it will help focus the controls upon those products, processes, and characteristics that are at risk. It is not the intention here to give a full appreciation of the FMEA technique and readers are advised to consult other texts. 

Inductive methods, such as check lists, Failure Mode and Effect Analysis (FMEA), event trees, decision tables, Analysis of Potential Problems (APP). These methods proceed from an initial cause of the deviation and construct a scenario ending with the final event. They are based on questions of the type What if ... 

HAZOP and What-If reviews are two of the most common petrochemical industry qualitative methods used to conduct process hazard analyses. Up to 80% of a company s process hazard analyses may consist of HAZOP and What-If reviews with the remainder 20% from Checklist, Fault Tree Analysis, Event Tree, Failure Mode and Effects Analysis, etc. An experienced review team can use the analysis to generate possible deviations from design, construction, modification, and operating intent that define potential consequences. These consequences can then be prevented or mitigated by the application of the appropriate safeguards. 

A failure mode and effects analysis (also known as failure mode and criticality analysis) examines a high-risk process in advance of an error to detect potential problems. The problems can then be fixed before an error occurs. It is used to discover the potential risk in a product or system. It involves examining a product or system to identify all the ways in which it might fail and allows for a proactive approach to fixing problems before they occur. 

Now ask, What can go wrong with this component The answer is your failure mode. Then ask, If this does go wrong, how will it affect customers This is your failure effect. Finally, brainstorm the possible reasons for your failure mode. These are your potential causes. Keep in mind that one item or function can have multiple potential failure modes, and each failure mode can have multiple potential causes. 

There are various types of analyses that are used for a process hazard analysis (PHA) of the equipment design and test procedures, including the effects of human error. Qualitative methods include checklists, What-If, and Hazard and Operability (HAZOP) studies. Quantitative methods include Event Trees, Fault Trees, and Failure Modes and Effect Analysis (FMEA). All of these methods require rigorous documentation and implementation to ensure that all potential safety problems are identified and the associated recommendations are addressed. The review should also consider what personal protective equipment (PPE) is needed to protect workers from injuries. 

Safety. It is becoming increasingly common to conduct quantitative assessments of process risks by failure modes and effects, fault tree, or other analytical alternatives. Thus, the probability of an accident times the corresponding potential loss is a cost factor which, although probabilistic. 

Before we can define the mission for any particular test or inspection system we must be able to specify customer needs. While a detailed framework for designing inspection systems is given in Section 7, we must consider now how to define such needs. One way is to apply a failure modes and effects analysis (FMEA) to the product and design a test and evaluation system to cover each of the potential failure modes. But this technique does not make the customer an explicit part of the design process, whereas we have seen earlier (Section 1) that direct customer input is increasingly needed in more customized products. A preferable technique is to begin with customer function and quality requirements as the basis for a list of product attributes that form the basis of test and inspection. In attributes inspection (Section 2.1), this list is often a defect list or fault list defining the discrete defects that the inspection system must ensure the customer never experiences. 

Failure mode and effects analysis is a design-evaluation procedure used to identify all conceivable and potential failure modes and determine the effect of each failure mode on system performance. This procedure is accomplished by formal documentation, which serves (1) to standardize the procedure, (2) as a means of historical documentation, and (3) as a basis for future improvement. 

It is critical to spend early development time using failure mode and effects analysis (FMEA) and establishing a design plan that minimizes or eliminates the potential failure modes identified as part of the design FMEA. Using multiple tests to evaluate failure modes is also a key component to success. 

Failure Modes and Effects Analysis analyses potential failures of systems, components or functions and their effects. Each component is considered in turn, its possible modes of failure defined and the potential effects delineated. 

A formal hazard analysis of the anticipated operations was conducted using Preliminary Hazard Assessment (PHA) and Failure Modes and Effects Analysis (FMEA) techniques to evaluate potential hazards associated with processing operations, waste handling and storage, quality control activities, and maintenance. This process included the identification of various features to control or mitigate the identified hazards. Based on the hazard analysis, a more limited set of accident scenarios was selected for quantitative evaiuation, which bound the risks to the public. These scenarios included radioactive material spills and fires and considered the effects of equipment failure, human error, and the potential effects of natural phenomena and other external events. The hazard analysis process led to the selection of eight design basis accidents (DBA s), which are summarized in Table E.4-1. 

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