What is the difference between FMEA and FMECA? Are they the same or different? The answer may surprise you. Let’s explore this topic.
When explaining the difference between FMEA and FMECA, it is essential to differentiate between applications in two different industries: Defense industries (and defense suppliers), and Automotive industries (including other industries that use the automotive standards).
In this article, I will characterize the definitions by industry, and show the differences and similarities. At the end, I’ll provide my view on whether we need to keep referring to FMEA and FMECA, as if they are different methods.
Defense industries, and defense suppliers
Many defense applications use the term FMECA. The current standard is Mil-Std-1629A, which will eventually be replaced by SAE1025.
FMECA is an acronym for Failure Mode, Effects and Criticality Analysis. The “C” in FMECA stands for Criticality Analysis. FMECA has its origin in Mil-Std-1629, published in 1974 by the Department of Defense, and revised in 1980 as Mil-Std-1629A. In Mil-Std-1629A, FMEA is the analysis done without Criticality Analysis (CA), and FMECA is an FMEA with an added Criticality Analysis.
According to Mil-Std-1629A:
FMEA is “a procedure by which each potential failure mode in a system is analyzed to determine the results or effects thereof on the system and to classify each potential failure mode according to its severity.”
FMECA is an FMEA with an added Criticality Analysis (CA). CA is “a procedure by which each potential failure mode is ranked according to the combined influence of severity and probability of occurrence.”
When doing work for the Department of Defense (DoD) or DoD suppliers, in most cases FMEA is done with CA, thus it is called FMECA. I rarely see FMEA done without CA, in military work.
Automotive industries, and other commercial industries
For the purpose of this article, I will uses my book, Effective FMEAs, to define the term FMEA. This definition is consistent with the FMEA standard SAEJ1739:2021, which is used by many automotive and commercial organizations.
Failure Mode and Effects Analysis (FMEA) is a method designed to:
1. Identify and fully understand potential failure modes and their causes, and the effects of failure on the system or end users, for a given product or process.
2. Assess the risk associated with the identified failure modes, effects and causes, and prioritize issues for corrective action, and
3. Identify and carry out corrective actions to address the most serious concerns.
FMEA is an engineering analysis done by a cross-functional team of subject matter experts that thoroughly analyzes product designs or manufacturing processes, early in the product development process. Its objective is finding and correcting weaknesses before the product gets into the hands of the customer, with the end result of risk reduced to an acceptable level.
So, what IS the difference between FMECA and FMEA?
The short answer is very little. I’ll explain.
Most people supporting defense industry applications use the term “FMECA” (following Mil-Std-1629A), which, as covered above, includes Criticality Analysis.
Most companies supporting commercial industries (automotive and others) use the term “FMEA” (following an FMEA standard such as SAEJ1739:2021), which always includes a type of risk prioritization similar to Criticality Analysis. SAEJ1739:2021 allows certain types of risk prioritization, such as SxO matrix, or Action Priority. It is important to note that SxO matrix in SAEJ1739 is identical to qualitative CA in Mil-Std-1629A.
In other words, in most applications both FMECA and FMEA use a risk prioritization method, such as SxO matrix or CA, in order to prioritize issues for corrective actions.
Separate from this discussion is a unique type of CA called Quantitative Criticality Analysis. See my article titled “Application of Quantitative Criticality Analysis in FMEA”
FMEA Process mapped to Application
All types of FMEA (or FMECA) follow an FMEA process. Here is a graphical representation of this process in six steps.
Mapping the 6 steps to both defense and automotive industry applications:
As you can see, both FMEA (automotive) and FMECA (defense) have the same process steps, up to Recommended Actions.
Modernizing Mil-Std-1629A
The SAE1025 team is in the process of modernizing Mil-Std-1629A. One of many changes being considered is to add a column for Recommended Actions. This will bring FMECA in defense applications very close to FMEA in automotive applications, in terms of scope of work.
Conclusion Survey Question
In my opinion, there is no longer any need to use both terms FMEA and FMECA. In most defense and commercial applications, FMEA or FMECA uses a form of CA. It will greatly simplify and focus the teaching and application of FMEA to settle on one or the other, FMEA or FMECA, and cease using both terms.
Short Survey
Please consider replying to this very short two-question survey:
- Which term do you prefer to use, FMEA or FMECA, and why?
- Should we cease using two different terms (FMEA and FMECA) and settle on one term?
Write me at carl.carlson@effectivefmeas.com or click on Ask a Question link below, and let me know your answers to the two questions. I’ll announce the results of this informal survey in a later article.
All survey responses are anonymous.
Next article
How should models be used in the FMEA process? This important subject will be discussed, including specific recommendations.
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