What is Failure Mode and Effects FMEA Analysis?


What is Failure Mode and Effects FMEA Analysis?

Neural Blog, 29th Aug 2006

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What is Failure Mode and Effects FMEA Analysis?

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FMEA and FMECA Analysis

FMEA are initiated because of a specific problem. Sometimes FMEAs are used as a proactive tool to reduce the potential for problems. Some companies implement FMEA to meet custo

What is Failure Mode and Effects FMEA Analysis?

Every product or process is subject to different types or modes of failure and the potential failures all have consequences or effects. A failure mode and effects analysis (FMEA) is a way to:

1) Identify the potential failures and the associated relative risks designed into a product or process. 2) Prioritize action plans to reduce those potential failures with the highest relative risk, and 3) Track and evaluate the results of the action plans.

Why do companies use FMEAs?

There are a number of reasons why companies use FMEA. Sometimes FMEA are initiated because of a specific problem. Sometimes FMEAs are used as a proactive tool to reduce the potential for problems. Some companies implement FMEA to meet customer requirements. Regardless of the reason for implementing FMEA, most people will agree that when FMEA are used correctly they can uncover potential problems before the problems get out to the customer and lead the way to a more robust process or product.

How can FMEA help companies improve quality and productivity?

FMEA can be used in many different ways, but the most common FMEA are Design-FMEA (DFMEA) and Process-FMEA (PFMEA). Design-FMEA should be used throughout the design process - from the preliminary design to when the product goes into production. Design-FMEA uncover potential failures associated with the product that could cause product malfunctions, shortened product life, and safety hazards to name a few. Process-FMEAs ideally should be conducted prior to starting up a new process, but are conducted on existing processes as well. Process FMEA uncover potential failures that can impact product quality, reduce process reliability, cause customer dissatisfaction, and create safety hazards.

How does an FMEA work?

Basically, an FMEA is a listing of all potential failures and their corresponding effects of the product or process under investigation. It is not unusual for an FMEA to list 50 to 200 different potential failures. If an FMEA has over 200 potential failures it is a good sign that the product or process under investigation should be broken into subunits, each with its own FMEA. For example, automotive companies don't conduct FMEA on the entire car, but rather individual components of the car.

Each potential failure mode will have at least one, if not several potential effects or consequences of the failure, potential causes of the failure, and current controls to prevent the failure from occurring or to detect the failure once it does occur. The potential effects of the failure are rated on a scale of 1 to 10 where 10 is the most severe consequence. The potential causes of the failure are rated in terms of the chance of the cause occurring, also on a scale of 1 to 10 where 10 is the greatest likelihood of occurrence. The ability to detect the failure prior to it occurring is also rated on a scale of 1 to 10 where 10 is the least likely chance of controlling or detecting the failure. The severity, occurrence, and detection ratings are multiplied together for each potential failure, effect, cause, and control combination to get the risk priority number (RPN) for that combination. The combinations with the highest RPNs are the potential failures that you need to focus your improvement efforts on.

How are FMEA conducted?

FMEA are typically conducted by small team of people, ideally each who has a slightly different view of the product or process under investigation. The variety of perspectives that a team can bring to an FMEA is what makes them so powerful. Any one person will not be able to develop as comprehensive and valuable am FMEA as a team of people can generate. Auditors are quick to pick up on FMEA that are developed by one person. Such FMEAs are typically generated to satisfy customer requirements, but are seen as having little value to the company. FMEA are a means to achieving better quality product and that's why they are now required by OEMs and industry standards in diverse industries such as automotive, medical device manufacturing, aerospace, and chemical processing.

What are some mistakes companies make when they use FMEA?

Here are the top ten reasons why FMEA fail:

One person is assigned to do the FMEA alone.

Not customizing the three rating scales with company specific examples so that they are meaningful to your company.

The design or process expert is either not included on the FMEA team or is allowed to dominate the FMEA team.

Members of the FMEA team have not been properly trained in the use of FMEA and become frustrated with the process.

The FMEA team gets bogged down with the minute details of the design or process, losing sight of the overall objective.

Rushing through the generation of potential failure modes in a hurry to move on to the next step of the FMEA, possibly overlooking significant but obscure failure modes.

Listing practically the same effect for every failure mode and not being more specific (for example "customer will be unhappy").

Stopping once the RPNs are calculated and not taking action on the highest risk failures.

Not reevaluating the RPNs once improvements have been made to assess the impact of the improvements.

How can my company get started using FMEA?

The first step in using FMEA is learning how to use them. While the FMEA process may seem relatively simple and straight forward, the process can become unwieldy for the first-time user. Once a team of people have gone through FMEA training, they will be ready to start their first FMEA project. Make sure that the project is well-defined so that the team doesn't get off on a tangent. While the FMEA process is best worked through using post-it notes and flipcharts, it helps to have an FMEA worksheet template in Microsoft Excel for documenting the process.

What is the best way to teach people how to conduct FMEA?

There is a basic methodology and terminology for conducting FMEA that all people on an FMEA team should understand. Having this knowledge prior to participating on an FMEA team will enable the team to work efficiently and effectively. FMEA training is available through seminars but this approach can be expensive when you need to train several people. There are also books available on FMEA, but there is no guarantee that if you give FMEA team members books that they will actually have the time to sit down and read them. The best way to train FMEA team members is with the FMEA Investigator computer-based training program. The FMEA Investigator is cost-effective because you pay one price and can train everyone at your site without additional per user costs. The FMEA Investigator is a solid training program. Once employees have completed the training they will be ready, willing, and eager to put what they have learned to use on an FMEA team.

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