This Month's Theme is Preliminary Risk Assessment
Next month's theme
will be "preparation for Design FMEAs"
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. Please send your questions about any aspect of FMEAs to Carl.Carlson@EffectiveFMEAs.com. Your contact information will be kept anonymous and all questions will be answered, even if they are not featured in the FMEA Corner.
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risk [risk, noun]
The probability or threat of quantifiable damage, injury, liability, loss, or any other negative occurrence that is caused by external or internal vulnerabilities, and that may be avoided through preemptive action.
What is Preliminary Risk Assessment, and what does it have to do with FMEA?
Short of doing FMEAs on all subsystems and components, which can be very expensive and time consuming, there needs to be a way to prioritize potential FMEA projects, to help identify which FMEAs to do. One way to do this prioritization is Preliminary Risk Assessment. Preliminary Risk Assessment is a procedure that uses company-specific criteria to select which FMEAs to perform.
What is an example of criteria used in Preliminary Risk Assessment?
The following example shows risk criteria that can be used to identify the subsystems or components that require Design FMEAs:
- Risk identified by System or Concept FMEA (Does the System or Concept FMEA point towards risk in the item?)
- Potential for safety issues (What is the degree of safety risk associated with the item?)
- New technology (What is the degree of new technology being introduced with the item?)
- New applications of existing technology (What is the level of new application for existing technology with the item?)
- History of significant field problems (What level of field problems has been associated with the item or similar items?)
- Potential for important regulation issues (What level of government regulation is associated with the item?)
- Mission-critical applications (To what degree can failures with the item bring about loss of primary mission?)
- Supplier capability (What is the risk associated with the supplier of the item?)
Note: These risk criteria can and should be tailored to the circumstances of an individual company or organization and applied to each item in the Bill of Materials.
How are the criteria used to identify potential FMEA projects?
Rank each risk criteria column for each row in the system hierarchy on a scale of risk, such as high, medium and low, or 1 to 5. In other words, assess the risk for each item in the Bill of Materials according to the risk criteria.
The final step uses simple arithmetic to multiply or add the cells in each row to obtain a risk index number for each of the subsystems or components in the system hierarchy. This index can then be used as input to the FMEA selection decision.
FMEA Tips of the Month
Tip 1: In many cases, specific changes to a design or manufacturing process are being considered. The nature of the proposed changes must be documented and becomes input to the Preliminary Risk Assessment. This includes changes in design, material, manufacturer, supplier, supplier design or process, usage environment, interfaces, specifications, performance requirements, or any other changes.
Tip 2: Preliminary Risk Assessment can be applied to Process FMEAs. Each of the steps in the process hierarchy (as documented in the process flow diagram) can be analyzed by the Preliminary Risk Assessment procedure, the same as with Design FMEA.
Scenario: Preliminary Risk Assessment is called Risk Discovery in Xfmea. The following fictitious Risk Discovery is from the hand brake subsystem of an all-terrain bicycle. It was performed in order to determine which hand brake components receive a Design FMEA. In this example, the hand brake subsystem is made up of brake lever, brake cable, brake pads and brake caliper.
Risk Discovery report generated from Xfmea for hand brake subsystem components:
Excerpt from Xfmea system hierarchy showing Risk Discovery column:
Problem: If you are a Reliability Engineer on the All-Terrain bicycle program, and have responsibility for ensuring needed FMEAs are performed for hand brake subsystem, how would you use this Risk Discovery? [Show/Hide Answer]
Answer: The Risk Discovery rating sums the individual ratings for each of the risk criteria. Based on this analysis, the highest rating for components of the hand brake subsystem is for the brake cable, followed by brake pads, brake lever and brake caliper. The All-Terrain project team can use this analysis as input to the decision on which FMEAs to do for the hand brake subsystem. Other factors to consider include project budget, project timing, and whether the component is designed in-house or by a supplier.
The Risk Discovery criteria are easily configurable in Xfmea. In this fictitious example, the All-Terrain team decided to do Design FMEAs on the hand brake subsystem (based on earlier Risk Discovery for bicycle subsystems) and the brake cable (based on this analysis). Given time and resources, they may also add a Design FMEA on the brake pads.
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.
Is it recommended to get the design engineers themselves to perform an FMEA or should this job stay with specialists like reliability and safety engineers? For the design engineers it would cost time and keep them away from their normally time-critical design tasks, as they have to be trained first in FMEA tasks. On the other side, it would increase their insight in quality parameters like reliability and safety of their products and systems engineering.
I normally try to perform the FMEA myself applying interview techniques, but in smaller companies (subcontractors), FMEA work is performed by the design engineers themselves.
What is your recommendation?
Carl: Thanks for your question. I have three comments for your consideration.
First, in my experience, FMEAs should be performed by a team, not by an individual. Below is an excerpt from my book on the subject of FMEA teams:
In small companies, a limited-scope design FMEA might include representation from design engineering, reliability/safety, test/field, and manufacturing. In larger companies, with a larger scope FMEA, additional representatives may be required.
Second, it is important to identify the roles and responsibilities for FMEA. Turning again to my book:
My preference is for a trained representative from reliability to facilitate the FMEA, with design engineering owning the document. However, I’ve seen companies successfully implement FMEA with design engineering doing the facilitation, as long as the correct team is formed and trained, and the facilitator is trained in the skills of facilitation.
Third, FMEA teams should be trained based on the following guidelines:
FMEA team members need training in the basics of FMEAs before the FMEA team meetings begin. This can either be full team training by an expert in FMEA methods, or at minimum, the team needs a good overview of FMEA fundamentals. If the FMEA team is not familiar with the basics of FMEAs, such as procedure, definitions, examples and lessons learned, then the meetings will be much longer than necessary and the results will be unsatisfactory.
At minimum, I recommend at least one person being well trained in the fundamentals of FMEA, and leading the effort. ReliaSoft's D470A and D470B are excellent courses. The FMEA team can then be trained in an overview of the fundamentals.
Let me know if this makes sense to you, and if you have any further questions.
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.