Performing a FMEA
To get the most out of your FMEAs, consider your analyses to be a continual process. The main idea behind a FMEA is to fully evaluate your system or process for potential failure modes and assess the effects of those failures so risk is minimized. As your system or process grows and changes, so should your FMEA. This way, you can take lessons learned from the past and apply them to your future work.
FMEAs are customizable. However, most FMEAs are built using commonly accepted standards to start, and then modified as needed. Relyence FMEA supports the most commonly used and effective FMEA standards.
We recommend going through Getting Started with Relyence FMEA as a starting point for learning Relyence FMEA. From there, you can proceed to building your own analyses. The following process is intended to be a starting point; you can adapt it as required for your needs.
1. Decide what type of FMEA you are going to perform
The first step in FMEA is to decide what type of analysis is best suited to your application. Design FMEAs are used to assess products or systems in the design stage so that you can ensure your product is well designed prior to manufacture. Hardware FMEAs are used to analyze hardware-based products of any kind. Process FMEAs are used to analyze failures associated with a process - such as product assembly, or a manufacturing procedure, or system integration. Piece-part FMECAs review each component of a system, down to the lowest piece-part level, determine all the failure modes and the resulting effects of those failures on the system.
2. Select a FMEA standard to use
There are several FMEA standards. Two of the most commonly used ones are SAE J1729 or MIL-STD-1629. These two standards share many of the same characteristics but varying in terms of how they assess risk. The SAE and standards similar to it, use Risk Priority Numbers (RPN) - a combination of severity, occurrence, and detection - to assess risk. The MIL standard uses criticality values that are based on actual probability values.
The most recently introduced FMEA Standard is the AIAG & VDA Failure Mode and Effects Analysis - FMEA Handbook. This handbook is similar to the SAE J1729 and AIAG standards. It introduces a new FMEA template, the FMEA-MSR (Monitoring and System Response) Worksheet, as well as the FMEA AP, or Action Priority rating method. The AP provides a priority level based on Severity, Occurrence, and Detection values. While the RPN (Risk Priority Number) is a risk assessment value based on Severity x Occurrence x Detection, AP was developed in order to give more emphasis to Severity first, then Occurrence, and then Detection.
In some cases, the FMEA standard you must employ is set by your organization.
It is important to note that FMEA implementations vary widely. Oftentimes, organizations base their FMEAs on a particular standard, but then modify it to more accurately meet their needs. Or, in some cases, they many define their own unique FMEA Worksheet. Relyence FMEA effectively handles any scenario with its built-in support for the widely used standards and customization features that allow you to modify the analysis for your needs.
3. Build your Analysis Tree (optional)
You may choose to employ some type of hierarchical structure to organize your FMEAs. For example, if you are performing a process FMEA, you may want to first define all the steps in your process and then perform a FMEA on each step independently. Or, if you are analyzing a product, you can use a hierarchical structure to define your product into its individual units. You could also use a tree to simply split up your analysis into separate parts for ease of management and team collaboration.
Each element in your tree has a separate FMEA Worksheet associated with it.
4. Use the FMEA Worksheet to enter your failure information
The main analysis of a FMEA is done in your FMEA Worksheet. The Worksheet is where you enter all the elements of your FMEA: the failure modes, their associated effects, causes, and recommended actions. When performing your analysis, it is best to work in an organized, step-by-step manner. Start by considering a singular failure mode. Then determine all the possible effects of that failure mode. Follow along with considering all possible causes for each effect. Filling your Worksheet out in this systematic approach helps to ensure that you have considered all possible failure situations.
Oftentimes, this part of FMEA is done using a collaborative, team-based approach. It is helpful to have as many team members involved in this process - from designers, engineers, analysts, and manufacturing engineers. This aids in ensuring the FMEA is complete and accurate.
5. Evaluate risks
Once you have a least some of your failure information gathered, you can begin to assess the risk of all the line items in your Worksheet. It is important to note that your FMEA does not have to be 100% complete at this point, you can start at any time and continually add failure modes, effects, and causes as you progress. A FMEA is valuable as a living document, so continual updating and reassessment is critical to its effectiveness.
If using Risk Priority Numbers (RPN), you define the severity, occurrence, and detection of each Worksheet item. Severity indicates how catastrophic a particular item is when it occurs. Occurrence defines how likely the item is to happen. Lastly, detection indicates how effectively the item failure can be detected. These three values are then combined to compute the RPN for that item. RPNs can then be used to rank items to allow you to spend your time and energy concentrating efforts on where they are most valuable.
If using actual criticality values, you enter the probability values associated with each Worksheet item, and then concentrate on mitigating and/or eliminating the most highly critical failure items.
The objective at this point in your analysis is to make sure you have well-defined risk criteria that you can use for risk ranking. Then applying those factors, you rank items based on your criteria.
6. Determine recommended actions
At this point in your FMEA, you have a ranking of failure concerns based on your risk criteria.
The next step is to look at the most highly critical items in your analysis and determine what the recommended actions are for these issues. The goal is to mitigate, or potentially eliminate, those items that are most catastrophic.
You may decide to assign a team to investigate and propose a plan, or multiple plans. You may decide you can only add detection mechanisms in some cases. Or, you may have to do feasibility studies in some cases to determine the best approach.
Once you have gathered the information on recommended actions, you then return to your FMEA Worksheet and update it with this information and re-assess risk levels. In the case of RPNs, you will have a new, second set of results RPNs values that take your recommended actions into account.
You continue this risk and evaluation process until you are comfortable your risks are all within acceptable levels.
7. Continually review and update
As stated before, FMEAs must be viewed as living documents. As design changes are made, update your FMEA to reflect these changes. As new, previously not considered failure modes occur, log them and process through a complete evaluation for risk assessment. As recommended actions are implemented, and perhaps modified over time, update your FMEA again with this new information.
Subsequently, as you move onto your next design or process, you can review the work already completed and adapt the lessons learned to your next generation product or process.