In FMECA, how is occurrence quantified?

In Failure Mode, Effects, and Criticality Analysis (FMECA), quantifying occurrence is essential to determining how likely it is for a failure mode to happen. The correct approach involves estimating the likelihood of each failure mode's occurrence, typically by using a scoring system that ranks the frequency on a scale, often from 1 to 10. This score reflects the probability of failure, allowing reliability engineers to prioritize which failure modes pose the most risk based on their likelihood of occurrence.

The scoring scale helps facilitate communication and understanding of risk levels, as higher scores indicate a greater likelihood of occurrence. This quantitative measure is crucial for guiding maintenance and design improvements by identifying areas requiring more attention.

While historical failure data does provide valuable insights, it primarily aids in understanding past occurrences rather than establishing a current quantitative assessment of potential failures. The approach that assigns a score based on asset value focuses more on the importance of the asset rather than the frequency of failures. Assessing the impact on production can illustrate the consequences of failures but does not directly quantify the likelihood of those failures happening. Thus, the use of a defined scoring system based on likelihood is the most effective and systematic method for quantifying occurrence in FMECA.