This Month's Theme is Using
"Mode of Operation" in FMEA Applications
Next month's theme will be "software FMEA"
Every month in FMEA Corner, join Carl Carlson, a noted expert in the field of FMEAs and facilitation, as he addresses a different FMEA theme (based on his book Effective FMEAs) and also answers your questions.
Questions and answers are a great way to learn about FMEAs, for both experienced and less experienced FMEA practitioners. Please feel free to ask any question about any aspect of FMEAs. Send your questions to Carl.Carlson@EffectiveFMEAs.com, and your contact information will be kept anonymous. All questions will be answered, even if they are not featured in the FMEA Corner.
mode [mohd, noun]
The Oxford English Dictionary defines "mode" as "a way or manner in which something occurs or is experienced, expressed, or done."
op·er·a·tion [op-uh-rey-shuh n, noun]
The Oxford English Dictionary defines "operation" as "an active process; a discharge of a function."
What is "mode of operation"?
"Mode of operation" or "operational mode" is a description of how the system is being used. This perspective is important for understanding the impacts of failure modes. More than one mission phase or operational mode may have to be considered for each potential failure mode.
What is an example of "mode of operation"?
For example, airplanes can operate during taxi on a runway; during take-off, cruise and descent; during landing and other possible modes of operation. The nature and consequence of failure can be very different depending on the mode of operation. Consider the failure of a landing gear. If it occurs during landing, it will most likely be more serious than during taxi. The identification of the operational mode is useful in evaluating the failure.
How is "mode of operation" used in an FMEA?
Where a system has unique operational modes that affect the nature and consequence of failure, it may be useful to identify and consider the mode of operation as part of the analysis. This will help when identifying the failure effect and subsequent cause of failure.
How to use "mode of operation" in Xfmea?
Since "mode of operation" or "operational mode" is usually associated with the failure mode in an FMEA, it can be set up in Xfmea as a user-defined field. Here’s how:
- In Xfmea, choose Project > Configurable Settings > Interface Style.
- In the Interface Style window, click Failure under the FMEA heading.
- In the "Mission Phase / Operational Mode" property, click No in the Enabled column to switch it to a "Yes." You can then change the display name to "Operational Mode" or other text, if desired.
- Click OK. The Operational Mode field will be activated and associated with failure modes in the FMEA hierarchy and worksheet.
FMEA Tip of the Month
When a complex system operates under distinctly different modes, it is important to include the unique operational mode when analyzing failure modes. Where applicable, understanding and documenting the various modes of operation is an important step in preparation for a System FMEA.
I’ve always wanted to know about FMEAs
The important thing is not to stop questioning. - Albert Einstein
A HotWire reader submitted the following question to Carl Carlson. To submit your own question about any aspect of FMEA theory or application, e-mail Carl at Carl.Carlson@EffectiveFMEAs.com.
I am working on an FMEA on a plating process. I have a question about a step in the process where the concentration of a mixture of substances in a solution affects the result of the process.
We currently do not know of a reliable detection system to know if the concentration is correct. Regularly, small quantities of the mix are added, but based on guesses.
The only point where it can be detected that the step is not performing well is at the end of the process. If it happens, the whole batch has to be reprocessed.
The severity of the effect of failure is high.
Any suggestion about how to improve the detection score? Do we only have to rely on the last check at the end? Thanks in advance, I visit your website a lot, and your book has been inspiring for me to cope with FMEA methodology.
Carl: Thanks for asking this question about improving detection. Based on the information you have provided, I'll make a comment and a suggestion.
First, there is no shortcut to detection improvement that I'm aware of. I would suggest to arrange a special meeting of the subject matter experts that have knowledge about the process you are analyzing, and brainstorm solutions to improve detection methods for determining the correctness of the concentration of the mixture. They may be able to come up with a creative idea to measure the concentration of the mixture and determine the correctness, earlier than end-of-line. Without knowing more about your plating process, I am not able to make specific suggestions. However, I have seen amazingly creative solutions from subject matter experts who are engaged in properly facilitated brainstorming sessions.
You can also try to reduce severity and occurrence rankings. Reference chapter 7 of my book for action strategies to reduce risk of severity, occurrence and detection.
Keep me updated on how this goes.
About the Author
Carl S. Carlson is a consultant and instructor in the areas of FMEA, reliability program planning and other reliability engineering disciplines. He has 35 years of experience in reliability testing, engineering and management positions, and is currently supporting clients from a wide variety of industries, including clients of HBM Prenscia. Previously, he worked at General Motors, most recently senior manager for the Advanced Reliability Group. His responsibilities included FMEAs for North American operations, developing and implementing advanced reliability methods and managing teams of reliability engineers. Previous to General Motors, he worked as a Research and Development Engineer for Litton Systems, Inertial Navigation Division. Mr. Carlson co-chaired the cross-industry team that developed the commercial FMEA standard (SAE J1739, 2002 version), participated in the development of SAE JA 1000/1 Reliability Program Standard Implementation Guide, served for five years as Vice Chair for the SAE's G-11 Reliability Division and was a four-year member of the Reliability and Maintainability Symposium (RAMS) Advisory Board. He holds a B.S. in Mechanical Engineering from the University of Michigan and completed the 2-course Reliability Engineering sequence from the University of Maryland's Masters in Reliability Engineering program. He is a Senior Member of ASQ and a Certified Reliability Engineer.
Selected material for FMEA Corner articles is excerpted from the book Effective FMEAs, published by John Wiley & Sons, ©2012. Information about the book Effective FMEAs, along with useful FMEA aids, links and checklists can be found on www.effectivefmeas.com. Carl Carlson can be reached at email@example.com.