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SAE J1739 offers guidelines on how to carry out a process FMEA. It offers assessment criteria frequently used in the automotive industry for rating the severity (S) of failure effects, along with the likelihood of occurrence (O) as well as the effectiveness of process controls to stop or detect (D) the cause or failure mode before the failure reaches the customer. The Risk Priority Number (RPN) is usually a measure utilized to assess risk and help recognize critical failure modes. It is calculated by multiplying the Severity, Occurrence, and Detection values, RPN = S x O x D. Even though it is true that larger RPN values generally indicate more critical failure modes, this is not always the case. In spite of the RPN value, always pay particular attention to any failure mode that has an effect resulting in a severity of 9 or 10.
A simple process FMEA example within SAE J1739 looks at each step involved in the process of applying wax to the inside of a car door. Each process step is considered and rated in accordance with the risk that it presents. With this example, the 3rd step calls for an operator to utilize a spray wand to manually apply the wax. Through the evaluation, this task is regarded to be the biggest risk area, since if it is not done correctly, then there could be too light or too heavy a layer of wax applied to the inside of the car door. This high-risk step could be the focus of our process FMEA analysis. The FMEA team would then look at ways in which this process step could possibly be improved.
Beyond just the automotive industry, process FMEA is now more commonly employed in the medical and health care industry, and it's also now being utilized in many service industries. Normally here, the goal is to recognize and prioritize processes that are high risk and then conduct a process FMEA on them. For each process the group would identify likely failure modes where the failure modes would represent various ways that a process or sub-process step could fail to give you the anticipated result.
In health care, this could be an analysis of the process steps in place to assure patient safety. For instance, maybe the analysis team would look into the process involved before a surgical procedure, or some of the process steps involved with post operation recovery procedures to find out if improvements might be made.
After failure modes have been determined for the high-risk processes, then the team would find possible effects for each failure mode. For the most significant effects a comprehensive analysis would be conducted to determine the root cause, after which suggestions would be made to redesign the process to either eliminate the failure mode or minimize the risk, if it did indeed occur.
This information is meant to merely introduce you to the technique of process FMEA. For additional process FMEA examples and a more in-depth discussion about this topic, please make use of some of the resources on our website.
