The term possibility of error and influence analysis, shortened FMEA, (English failure mode and effects analysis) designates an analytic method, in order to find potenzielle weak points. In the framework of the quality management the FMEA is used for preventing antibugging. The FMEA is used in particular in the Design and/or development phase of new products or processes.

FMEA follows the basic idea of a taking precautions fault prevention in place of a after-ensuring error recognition and - correction (error accomplishment) by early identification of potenzieller error causes already in the design phase. Thus otherwise resulting control and error subsequent costs in the production phase are avoided or in the field (at the customer) and the costs are altogether lowered. Besides the repetition of lack of Design is avoided by a systematic proceeding and the realizations won thereby with new products and processes.

The FMEA is taken up since 1980 as loss effect analysis into the DIN 25448. The methodology of the FMEA is to be used in the early phase of the product development (planning and development) within the Produktlebenszyklusses, since a cost/use optimization is most economical in the development phase. Because the later an error is discovered, the more with difficulty and more cost-intensively its correction will be.

Kinds

The FMEA can be divided into three kinds:

• The system FMEA examines a cooperating of subsystems in a superordinate system group and/or a cooperating of several components in a complex system. It aims thereby at the identification of potential weak points, in particular also at the interfaces, which could result from cooperating the individual components.

• The construction FMEA aims at the construction of individual products or construction units and examines these on potential weak points or loss possibilities.

• The process FMEA relies on the results of the construction FMEA and is concerned with possible weak points in the manufacturing or achievement process.

The system FMEA and the construction FMEA are combined into the so-called product FMEA, since the system which can be regarded cannot be usually dissolved clearly.

The SYSTEM FMEA product is used within the development process. Their task is it to examine the product on fulfilment of the functions specified in product requirement specifications. Suitable measures are to be planned for avoidance or discovery of the potential errors for all risky parts of a product. The SYSTEM FMEA on construction unit level corresponds to the past definition of the construction FMEA. It serves for the analysis of all construction unit characteristics, which are necessary for the fulfilment of the demanded construction unit function.

The system FMEA process is used still within the production planning process. It develops logically on the results of the construction FMEA. An error of the SYSTEM FMEA product, a whose cause lies in the production process, is transferred logically as error to the process FMEA. Task of the system FMEA process is it to examine the entire production process of a product for the suitability for the production of the product. Suitable measures are to be planned to their avoidance or discovery for all errors, which can occur during the production of the product.

Application

With application first a team from coworkers of different enterprise functions (interdisciplinary team) is educated. To include in particular construction, attempt, production planning, manufacturing execution, quality management etc. is the analysis process by forms (QS-9000) or appropriate software in formalized way (VDA4.2) is then accomplished.

The FMEA contains

• a containment of the regarded system,
• a structuring of the regarded system,
• Definitions of functions of the structural components,
• an analysis on potenzielle error causes, error kinds and error sequences, which are derived directly from the functions of the structural components,
• a risk evaluation,
• Proposals for solution and/or measure to priorisierten risks
• a pursuit of agreed upon avoidance and discovery measures and
• a residual risk evaluation and/or - evaluation.

Potential errors are determined analyzed, by error location one locates, the error, the error sequence is described and afterwards the error cause is determined. For the determination of conceivable error causes frequently a so-called cause effect diagram is provided. It is possible that due to a recognized error cause referring to possible measures to the antibugging can be derived directly.

The risk evaluation takes place via determination of a so-called risk priority number (RPZ). The RPZ quantifies the probability of occurrence (the error cause), meaning (the error sequence) and probability of discovery (the error or its cause) in a characteristic number. For this these three aspects are judged in each case with a number between one and ten. By multiplication of these three numbers is calculated the RPZ, which can take accordingly values between one and thousands. (RPZ=A \ cdot B \ cdot E) a goal is it to measure the meaning and the rank of an error in order to derive from this priorities for the measures which can be seized.

Measures

Measures are directed toward it,

• A

The risk evaluation finds in the current FMEA no longer alone by the RPZ specified already instead of separates rather at the following operational sequence:

Highest priorities have high meanings (10), afterwards the product of meaning and probability of occurrence regarded (B*A), this is called also criticality.

Only then the RPZ seizes for the prioritization of the remaining points.

Evaluation

The evaluation takes place via interdisciplinary teams, which assign points of "“1"” in each case to "“10"”.

• Probability of occurrence (small = "“1"” to highly = " 10"”)
• Probability of discovering (highly = "“1"” to small = " 10"”)
• Meaning of the error sequence is evaluated from the view of the Kundens (small = "“1"” to highly = " 10"”).

The customer can be here both the final customer and (e.g. internal) an intermediate customer, who demand the FMEA. Risk priority numbers over 120 require usually counter measures, this variert however clearly from company to company. Also high individual values (8 - 10) can pull despite small risk priority number activities.

After the Erstbewertung and processed measures takes place a renewed risk evaluation: By repeated determination a risk priority number RPZ is examined whether the planned measures promise a satisfying result. (The meaning of the error sequence remains unchanged.) the result does not correspond yet to the demanded claims of quality of the customer, then further avoidance or discovery measures must be seized and/or solutions be developed.

The FMEA is embodied further in the DIN 25448 and Einflussanalyse*. The VDA writing 4, part of 2 recommends details a systematic proceeding.

Historical

For the first time a description was published to the FMEA method as United States Military Procedure: MIL-P-1629 - Procedures for Performing A failure mode, Effects and Criticality analysis; November 9, 1949. The surface covering employment of the FMEA within the range of the automobile industry by Ford one initiated, after there were look up-exciting problems in the 70's with the Model Pinto

At the beginning of the 1980er years published Ford publications to the FMEA formed the basis for the QS-9000 FMEA description of method. 1996 were published by the federation of the automobile industry (VDA) improved FMEA systematics. In the third edition of the QS-9000 FMEA description of method available since 2002 some elements of the VDA beginning were transferred.

The fields of deployment of the FMEA expanded in the course of the time. The FMEA found the acknowledgment within automotives the range originally settled in the military range over an intermediate stage "“air and space travel"”. Since the FMEA a universal method model is the basis, she finds also within other ranges, within which systematically one works, her fields of deployment, e.g. to medical technology, foodstuffs industry (than HACCP system), equipment construction, software development.

Derivatives

The FMEA method under the designation Design Review Based on failure mode (DRBFM), focused on changes, was developed further by Toyota. DRBFM is to waive the separation between development and quality process and to merge the development engineer more directly into the quality process with.

On food the "“Hazard is analysis and Critical control POINT concept (shortened: HACCP concept, German: Endangerment analysis and critical inspection points) aligned. Originally developed by NASA as well as a supplier, around which ensure security of the astronaut food, it is recommended today by the US-American national Academy OF Sciences as well as by the Food and Agriculture Organization of the UN.

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