Before I joined Minitab, I worked for many years in Penn State's College of Agricultural Sciences as a writer and editor. I frequently wrote about food science and particularly food safety, as I regularly needed to report on the research being conducted by Penn State's food safety experts, and also edited course materials and bulletins for professionals and consumers about ensuring they had safe food.
After I joined Minitab and became better acquainted with data-driven quality methods like Six Sigma, I was surprised at how infrequently some of the powerful quality tools common in many industries are used in food safety work.
So I was interested to see a recent article on the Food Safety Tech web site about an application of the tool called FMEA in pathogen testing.
What Is an FMEA?
The acronym FMEA is short for "Failure Modes and Effects Analysis." What the tool really does is help you look very carefully and systematically at exactly how and why things can go wrong, so you can do your best to prevent that from happening.
In the article, Maureen Harte, a consultant and Lean Six Sigma black belt, talks about the need to identify, quantify, and assess risks of the different pathogen detection methods used to create a Certificate of Analysis (COA)—a document companies obtain to verify product quality and purity.
Too often, Harte says, companies accept COA results blindly:
[They] lack the background information to really understand what goes into a COA, and they trust that what is coming to them is the highest quality.
Harte then proceeds to explain how doing an FMEA can make the COA more meaningful and useful.
FMEA helps us understand the differences between testing methods by individually identifying the risks associated with each method on its own. For each process step [in a test method], we ask: Where could it go wrong, and where could an error or failure mode occur? Then we put it down on paper and understand each failure mode.
Completing an FMEA
Doing an FMEA typically involves these steps:
- Identify potential failure types, or "modes," for each step of your process.
- List the effects that result when with those failures occur.
- Identify potential causes for each failure mode.
- List existing controls that are in place to keep these failures from happening.
- Rate the Severity of the effect, the likelihood of Occurrence, and the odds of Detecting the failure mode before it causes harm.
- Multiply the values for severity, occurrence, and detection to get a risk priority number (RPN).
- Improve items with a high RPN, record the actions you've taken, then revise the RPN.
- Maintain as a living document.
You can do an FMEA with just a pencil and paper, although Minitab's Companion process improvement software include forms that make it easy to complete the FMEA—and even share data from process maps and other forms you'll may be using.
Here's an example of a completed Companion FMEA tool:
1) In Process Map - Activity, enter each process step, feature or type of activity. In the example above, it's preparation of growth culture and incubation. We also list the key components or inputs of each step.
2) In Potential Failure Mode, we note the ways the process can fail for each activity. There may be many ways it could fail. In the example, we've identified contamination of growth medium and incubating cultures at the wrong temperature as potential failure modes.
3) In Potential Failure Effects, we detail the possible fallout of each type of failure. There may be multiple failure effects. In the example above, contaminated growth culture could lead to the waste of perfectly good raw materials. An improperly performed incubation might lead to undetected pathogens, and possibly unsafe products.
4) In SEV (Severity Rating), we assign severity to each failure effect on a 1 to 10 scale, where 10 is high and 1 low. This is a relative assignment. In the food world, wasting some good materials is undesirable, but having pathogens reach the market is obviously much worse, hence the ranking of 6 and 9, respectively.
5) In OCC (Occurrence Rating), estimate the probability of occurrence of the cause. Use a 1 to 10 scale, where 10 signifies high frequency (guaranteed ongoing problem) and 1 signifies low frequency (extremely unlikely to occur).
6) In Current Control, enter the manner in which the failure causes/modes are detected or controlled.
7) In DET (Detection Rating), gauge the ability of each control to detect or control the failure cause/mode. Use a 1 to 10 scale, where 10 signifies poor detection/control and 1 signifies high detection/control (you're almost certain detection to catch the problem before it causes failure).
8) RPN (Risk Priority Number) is the product of the SEV, OCC, and DET scores. The higher the RPN, the more severe, more frequent, or less controlled a potential problem is, indicating a greater need for immediate attention. Above, the RPN of 81 for potential incubation error indicates that that type of failure should get higher priority than contaminated cultures. .
9) If you're doing FMEA as part of an improvement project, you can use it to prioritize corrective actions. Once you've implemented improvements, enter the revised SEV, OCC, and DET values to calculate a current RPN.
The Benefits of an FMEA
When you've completed the FMEA, you'll have the answers to these questions:
What are the potential failure modes at each step of a process?
What is the potential effect of each failure mode on the process output, and how severe is it?
What are the potential causes of each failure mode, and how often do they occur?
How well can you detect a cause before it creates a failure mode and effect?
How can you assign a risk value to a process step, that factors in the frequency of the cause, the severity of failure, and the capability of detecting it in advance?
What part of the process should an improvement project focus on?
Which inputs are vital to the process, and which aren't?
How can reaction plans be documented as part of process control?
And if your understanding of the steps that underlie your Certificate of Analysis is that thorough, you will be able to stand behind it with much more confidence.
Where could you apply an FMEA in your organization?