This Month's Theme is Using Design FMEAs to Improve Design Verification Plans
Next month's theme will be using process FMEAs to improve process control plans
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.
Design Verification Plan
A Design Verification Plan (DVP) documents the strategy that will be used to verify and ensure that a product or system meets its design specifications and other requirements. Each of the product requirements is listed in the DVP, along with the physical test or analytical method that will determine if the requirement is met.
What is the relationship between Design FMEA and DVP?
The System or Design FMEA is a key contributor to the effectiveness of the Design Verification Plan. The linkage between the FMEA and the DVP plan goes two ways. In the first, the FMEA team includes representation from the testing department in order to ensure that the team considers all needed input from testing as part of the analysis. In the second, the FMEA team ensures that the Design Verification Plan is impacted in a positive way by the results of the FMEA.
How do FMEAs improve DVPs?
Specifically, when the FMEA team identifies failure modes and associated causes that are not currently well detected in test plans or procedures, the test plans and procedures should be updated and improved so all failure modes of concern are detected during testing. Any changes to test procedures or test plans should be identified as FMEA recommended actions.
Why enter DVP improvements in the Recommended Actions column of the FMEA?
The short answer is everything that the FMEA team believes needs to be done differently from what is already planned or in place should go in the Recommended Actions column of the FMEA. The reason for this is that the entries in the Recommended Actions column have additional information to facilitate execution of the task that is recommended, such as the person who is responsible for the execution of the task, the target date when the task should be completed and other project management information.
What does a DVP look like?
The following is a fictitious and simplified example of a Design Verification Plan for a Hand Brake Subsystem, excerpted from chapter 6, Figure 6.32 of my book, Effective FMEAs. The "Design Controls" from the Design FMEA are transferred to the "Test/Specification Method" column of the Design Verification Plan. The test/verification team fills out the rest of the DVP. In this example, note that in addition to transferring the design controls to the DVP, the Design FMEA recommended actions that are related to test improvements are also added. The columns of the DVP are easily configurable in Xfmea.
How is a Design FMEA synced to a DVP in Xfmea?
In Xfmea, it is easy to sync the Design FMEA to the DVP. The best time to do this is when the Design FMEA is completed up through Recommended Actions. That way both current design controls, as well as improvements that are recommended to the DVP (from the Recommended Actions column), can be included. The resulting DVP will need to be reviewed and updated to ensure it reflects input from the test/verification team, including samples sizes, etc.
To sync a Design FMEA with a DVP, choose Analyses > Add DVP&R.
The resulting DVP is shown next (synced items will vary depending on software configuration settings). The test/verification team can then enter the remaining information into the DVP.
What risk factors drive changes to the DVP?
In general, when the current design controls (such as specific tests) do not adequately detect a higher risk failure mode/cause, the FMEA team should recommend additions or modifications to the DVP in order to improve the detection capability of the failure mode/cause.
One of the objectives of Design FMEA is to improve the Design Verification Plan. Following the suggestions in this article will help FMEA teams accomplish this purpose.
FMEA Tip of the Month
Some FMEA practitioners enter suggested tests in the Recommended Actions of the Design FMEA. This is not a good practice. The best practice is to recommend modifications to the DVP. For example, if the Design FMEA team wishes to add a new cable strength test, the recommended action in the FMEA would be, "add cable strength test to DVP." If the FMEA team enters "conduct cable strength test" to the FMEA Recommended Actions, both the FMEA and the DVP will be tracking the accomplishment of the cable strength test, which is double tracking.
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.
Since FMEA is a living document, I always thought that reviewing of it should be as simple as possible. If the FMEA document is maintained only in a paper form, is it permissible to update this document without saving copies of last version? Or should we have a story of changes? What is the way it is usually done?
Carl: The policy for maintaining FMEA records is up to each company and should be well thought out. Since FMEAs are legal documents, the policy for updating and retaining FMEAs should be consistent with company legal guidelines. Most companies maintain records of FMEA versions once the original FMEA has been completed through Recommended Actions and Actions Taken. Each subsequent FMEA version has its own unique identification number. This provides a record of changes without adding unduly to the burden of maintaining records. Xfmea has a "change log" feature that, when activated, allows users to track details of each change made.
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 30 years of experience in reliability testing, engineering and management positions, and is currently supporting clients of ReliaSoft Corporation with reliability and FMEA training and consulting. Previous to ReliaSoft, 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.
Material for the FMEA tips, problems and solutions 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.