Function | Design | The studied functions correspond to the functions implemented by the analyzed system. The purpose is to determine potential failure modes for each aspect of the functions to prevent these failures. |
Operation | Process | The studied operations correspond to the operations defined in a manufacturing process. The purpose is to determine potential failure modes that may affect the operations, their causes in terms of resource failure modes or MBOM failure modes. |
Failure Mode | Design and Process | A failure mode is the core object of a RAMS model or a quality model, and represents a failure. A failure mode is defined as the manner in which
a product or process could fail to meet its intended function. |
Failure Effects | Design and Process | The potential effects of failures are defined as the effects of the failure modes at higher
levels of the system, including customer level, regulatory level, environmental
level... The potential failure effects are determined by the analysis of the
consequences of the failures and the severity of these consequences. Effects are
found in the higher-level environment. |
Severity (S) | Design and Process | The severity of a failure mode is an assessment of the impact level of a failure at
the customer level. The effect rating is comprised between 1 and 10, where 10 is the most severe impact on the system's performance. |
Failure Causes | Design and Process | The potential causes of failures are defined as an indication
of why the failures could occur. This means that something could be corrected. The causes are found in the system. |
Prevention Controls | Design and Process | The prevention controls correspond to determine: what goes wrong, why, and how. The purpose is to prevent failures by preventing the cause of
the failure or failure mode. |
Occurrence (O) | Design and Process | The occurrence of the failure cause corresponds to how often the cause of a failure may occur given the prevention controls. The likelihood of occurrence chance is comprised between 1 and 10, where 10 is the most likely to occur. |
Detection Controls | Design and Process | The detection controls correspond to determine the efficiency of the prevention means. The
purpose is to detect failures by detecting the cause of the failure or failure
mode. |
Detection (D) | Design and Process | The detection is an assessment of how well the controls detect the cause of the failure or the failure mode. The corresponding rating is comprised between 1 and 10, where 10 is corresponds to no solution to detect the failure mode before it affects the system. |
Risk Priority Number (RPN) | Design and Process | When performing a process or design FMEA, the risk priority number for a failure is a calculation to sort
the risks from highest to lowest. The RPN corresponds to: RPN = Severity x Occurrence x Detection. |
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Action Priority (AP)
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Design
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An AP rating is determined using the severity, occurrence, and detection values.
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Actions | Design and Process | The purpose of defining corrective actions is to decrease the RPN by reducing the occurrence or improving the detection of failure. |