FMEA (Failure Mode and Effects Analysis)
The FMEA is applied especially in the design and development phase of new products and processes and is an analytic method of reliability engineering. It identifies potential design and process vulnerabilities, assessing the inherent risks. As to quality and reliability engineering, FMEA provides the foundation to act preventatively to avoid failures and to rise the technical reliability.
Key Stages
1
Planning and preparationKey Stages
Design FMEA
- •Refers to products and their features.
- •Started at an early stage and is cultivated throughout all sample phases of development.
Process FMEA
- •Refers to procedures (e.g. welding processes).
- •Executed with the aim of safeguarding process planning.
FMECA (Failure Mode and Effects and Criticality Analysis)
FMEA with an extension to include a criticality analysis. It adds a combined evaluation of the failure probability and the expected defect, allowing the urgency of actions to be ranked.
FMEDA (Failure Mode and Effects and Diagnostic Analysis)
FMEA with an extension to include a diagnostic analysis. A statement is made on whether a root cause is safety critical and whether its detection is possible.
Parameters required by standards include:
- •IEC 61508: SFF (Safe Failure Fraction)
- •ISO 26262: SPFM (Single Point Fault Metric) and LFM (Latent Fault Metric)
SFF is the percentage of harmless or detected safety-critical failures relative to the total number of failures.
FTA (Fault Tree Analysis)
Top-down method used to analyze and structurally visualize failure events.
A TOP event is first selected. This represents the failure event at the top of a downward branching fault tree and defines the main event whose possible causes are examined.
All sub-events are collected and arranged as branches that may lead to the TOP event.
Using predefined event symbols and logical relationships ("AND"/"OR"), the fault tree can be structured in greater detail.
By evaluating the occurrence probability of each sub-event, the probability of the TOP event can be inferred.
FuSaCo (Functional Safety Concept)
To meet safety objectives, functional solutions are discussed and defined.
- •Conceptual design to meet safety objectives
- •Definition of safety requirements for each safety objective
- •Definition of safety mechanisms
The FuSaCo is compiled during the concept phase of the safety lifecycle.
