How to Complete an FMEA (Failure Modes and Effects Analysis)

This Article is the third in a four part series to show you “How to Complete a Six Sigma Root Cause Analysis”. The series covers four tools:

• The SIPOC(R) Diagram
• The Input (or Variables) Map
• The C&E Matrix
• The FMEA (Failure Modes and Effects Analysis)

In this article, we will be discussing the FMEA or the Failure Modes and Effects Analysis

Every product or process is subject to different types or modes of failure and the potential failures all have consequences or effects.

The FMEA is used to:

• Identify the potential failures and the associated relative risks designed into a product or process
• Prioritize action plans to reduce those potential failures with the highest relative risk
• Track and evaluate the results of the action plans

The Steps to Complete an FMEA:

Review and label the Process Steps (using your process map) and the intended function or functions of those steps.

Consider the Potential Failure Modes for each component and its corresponding function.

• A potential failure mode represents any manner in which the component or process step could fail to perform its intended function or functions.

 Determine the Potential Failure Effects associated with each failure mode. The effect is related directly to the ability of that specific component to perform its intended function.

• The effect should be stated in terms meaningful to product or system performance.
• If the effects are defined in general terms, it will be difficult to identify (and reduce) true potential risks.

For each failure mode, determine all the Potential Root Causes. Use tools classified as root cause analysis tool, as well as the best knowledge and experience of the team.

For each cause, identify Current Process Controls. These are tests, procedures or mechanisms that you now have in place to keep failures from reaching the customer.

 Assign a Severity ranking to each effect that has been identified.

• The severity ranking is an estimate of how serious an effect would be should it occur.
• To determine the severity, consider the impact the effect would have on the customer, on downstream operations, or on the employees operating the process.

The severity ranking is based on a relative scale ranging from 1 to 10.

• A “10” means the effect has a dangerously high severity leading to a hazard without warning.

Sample of a Severity Scale

Assign the Occurrence Ranking

• The Occurrence ranking is based on the likelihood, or frequency, that the cause (or mechanism of failure) will occur.
• Once the cause is known, capture data on the frequency of causes. Sources of data may be scrap and rework reports, customer complaints, and equipment maintenance records.

Assign the Detection Rankings

• To assign detection rankings, identify the process or product related controls in place for each failure mode and then assign a detection ranking to each control. Detection rankings evaluate the current process controls in place.
• A control can relate to the failure mode itself, the cause (or mechanism) of failure, or the effects of a failure mode.
• To make evaluating controls even more complex, controls can either prevent a failure mode or cause from occurring or detect a failure mode, cause of failure, or effect of failure after it has occurred.

Calculate the Risk Priority Number (RPN)

• The RPN is the Risk Priority Number. The RPN gives us a relative risk ranking. The higher the RPN, the higher the potential risk.
• The RPN is calculated by multiplying the three rankings together. Multiply the Severity ranking times the Occurrence ranking times the Detection ranking
• Calculate the RPN for each failure mode and effect

Prioritize the Risks by Sorting the RPN from Highest Score to Lowest Score. This will help the team determine the most critical inputs and the causes for their failure

Develop Action Plan:

• Taking action means reducing the RPN. The RPN can be reduced by lowering any of the three rankings (severity, occurrence, or detection) individually or in combination with one another

 Who is Responsible:

• This is a very important step in Taking Action!
• Be sure to include person(s) responsible and the deadline

 Take Action:

• The Action Plan outlines what steps are needed to implement the solution, who will do them, and when they will be completed.
• Most Action Plans identified during a PFMEA will be of the simple “who, what, & when” category.
• Responsibilities and target completion dates for specific actions to be taken are identified.

Recalculate the Resulting RPN :

• This step in a PFMEA confirms the action plan had the desired results by calculating the resulting RPN.
• To recalculate the RPN, reassess the severity, occurrence, and detection rankings for the failure modes after the action plan has been completed.

About the Author, Kevin Clay, President & CEO of Six Sigma Development Solutions, Inc.

Kevin Clay is a Six Sigma Master Black Belt and a Lean Master Practitioner. Kevin brings over 20 years of operational experience into the classroom. He has a wide range of Lean and Six Sigma project experience in industries such as manufacturing, food processing, residential and commercial construction, insurance, banking, healthcare, etc.

Kevin has taught Public Lean Six Sigma Green Belt and Lean Six Sigma Black Belt Certification Training courses all over the world. Some of the locations he currently teaches are: Albuquerque, New Mexico | Anchorage, Alaska | Atlanta, Georgia | Austin, Texas | Boston, Massachusetts | Calgary, Canada | Charlotte, North Carolina | Chicago, Illinois | Cincinnati, Ohio | Cleveland, Ohio | Columbus, Ohio | Dallas, Texas | Denver, Colorado | Detroit, Michigan | Dubai, UAE | El Paso, Texas | Fort Smith, Arkansas | Honolulu, Hawaii | Houston, Texas | Indianapolis, Indiana | Jacksonville, Florida | Kansas City, Missouri | Las Vegas, Nevada | London, England | Los Angeles, California | Louisville, Kentucky | Memphis, Tennessee | Mexico City, Mexico | Milwaukee, Wisconsin | Minneapolis, Minnesota | Montreal, Canada | Nashville, Tennessee | New Orleans, Louisiana | New York City, New York | Northwest Arkansas | Orlando, Florida | Philadelphia, Pennsylvania | Phoenix, Arizona | Pittsburgh, Pennsylvania | Portland, Oregon | Raleigh, North Carolina | Salt Lake City, Utah | San Diego, California | Seattle, Washington | St. Louis, Missouri | Tampa, Florida | Toronto, Canada | Vancouver, Canada | Washington, DC

Kevin also works with many organizations onsite at their facilities to provide Operational Excellence to these companies all over the globe.

One of Kevin’s favorite courses to teach is the Lean Six Sigma Yellow Belt course because it gets everyone in the organization engaged in simple root cause analysis and bring many small rapid improvements to the organization. 

One of Kevin’s favorite quotes is:

"The master in the art of living makes little distinction between his work and his play, his labor and his leisure, his mind and his body, his information and his recreation, his love and his religion. He hardly knows which is which. He simply pursues his vision of excellence at whatever he does, leaving others to decide whether he is working or playing. To him he's always doing both." -Zen Buddhist

You can contact the Author Kevin Clay of at [email protected] or 479-739-4940