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FMEA Types
All FMEAs assess the impact of failure on system performance and safety. However, FMEAs are generally categorized based on whether they analyze the design of the product or the processes involved in manufacturing and assembling the product. In addition to choosing the FMEA standard to use in the analysis, you must choose the type of FMEA to perform. The FMEA module supports process FMEAs, functional FMEAs, and component FMEAs
Type
Description
Process FMEA
This type examines the ways that failures in manufacturing and assembly processes can affect the operation and quality of a product or service. You can construct a process FMEA at any level to evaluate possible failure modes in the process. Process FMEAs also help to identify limitations in the equipment, tooling gauges, or operator training. This information indicates what you can do to prevent potential process failures before the first production run. Based on this knowledge, you can determine the corrective actions that need to be taken.
Functional FMEA
This type examines the intended functions that a product, process, or service is to perform rather than the characteristics of the specific implementation. To develop a functional FMEA, you generally use a functional block diagram to identify the top-level failure modes for each block in the diagram. For example, a functional FMEA would indicate that a capacitor is intended to regulate voltage and then analyze the effect of the capacitor not regulating voltage. It would not analyze what would occur if the capacitor fails open or fails shorted.
Component FMEA
This type examines characteristics of a specific implementation to ensure that the design complies with requirements for failures. Component failures can be used to evaluate loss of end-item function, single-point failures, and fault detection and isolation. After the individual items of a system are uniquely identified in the later design and development stages, a component FMEA can be developed to assess the failure causes and effects of failure modes on the lowest-level system items. Detailed FMEAs for hardware, commonly referred to as piece-part FMEAs, are the most common FMEA applications. However, individual system components can be software routines or process steps.
FMEAs are best begun during the conceptual design phase, long before specific hardware information is available. The functional approach is generally the most practical and feasible approach by which to begin an FMEA. This is especially true for large, complex products or processes. It is far easier to understand them by their functions than by the details of their operation. Variations in design complexity and data availability dictate not only the FMEA type but also the level of detail. Some cases might require that part of the analysis be performed at the functional level and other portions at the component level.
You create functional FMEAs to examine the interconnections between system elements. The goal is to determine and record the failures between components to verify compliance requirements are met. These FMEAs are sometimes called interface FMEAs. For interface FMEAs, you identify failure modes for each interface type. These types might include electrical cabling, wires, fiber optic lines, mechanical linkages, hydraulic lines, pneumatics lines, signals, software, and more. Beginning an interface FMEA as soon as the system interconnections are defined ensures that proper protocols are used. It also ensures that all interconnections are compliant with design requirements.
For more complex systems, FMEAs often include multiple approaches to FMEA development. For example, the process might begin with defining initial requirements in a functional FMEA. This functional FMEA might later progress to an interface FMEA. Later yet, this functional FMEA might progress to a component or piece-part FMEA.