Background: FMEA and Related Analyses

The Xfmea software facilitates analysis, data management and reporting for Failure Mode and Effects Analysis (FMEA) and related analyses, such as Criticality Analysis (FMECA), design verification plans (DVP&Rs), process flow diagrams (PFDs), process control plans (PCPs) and design reviews based on failure mode (DRBFM). This chapter provides a brief, general overview of the principles and applications for these methodologies.

Failure Mode and Effects Analysis (FMEA)

Failure Mode and Effects Analysis (FMEA) is a methodology designed to:

Identify and fully understand potential failure modes for a product or process.
Assess the risk associated with those failure modes and prioritize issues for corrective action.
Identify and carry out corrective actions to address the most serious concerns.

The history of FMEA goes back to the early 1950s and 1960s and the tool has been adapted in different ways for many different purposes. Since there is variation among practitioners as to the specific terminology and reporting formats, this chapter will discuss general requirements and common techniques.

FMEA Applications and Benefits

Usually, the primary objective of an FMEA is to identify and mitigate risks in a product or process in order to improve the design. In addition, since the FMEA provides a central location for reliability-related information for the product or process, it can be used as a learning tool for new engineers, a resource when considering modifications to the design or developing a similar design, a resource for service personnel to identify possible corrective actions when problems occur in the field, and so on.

FMEA is often performed in conjunction with Design for Reliability (DFR), Design for Six Sigma (DFSS), ISO quality programs and other initiatives. It also may be performed to satisfy a customer or regulatory requirement.

When performed effectively, an FMEA can contribute to improved designs for products and processes, resulting in higher reliability, better quality, increased safety, enhanced customer satisfaction and reduced costs.

When to Perform an FMEA

Many references cite three situations in which an FMEA commonly may be performed:

Creating a new design or process
Modifying an existing design or process
Using an existing design or process in a new environment

The FMEA should be performed during the "window of opportunity" when it can most effectively impact the product or process design. In general, it should be an "up-front" activity, rather than "after-the-fact." Citing the "factor of 10 rule," most practitioners agree that it is more cost effective to correct reliability issues early in the process.

Types of FMEA

FMEA analyses are often referred to by type. The most common designations are:

Design FMEA (DFMEA): an analysis that focuses on design-related issues. It may be used, for example, to analyze a new product design before it goes into full production.
Process FMEA (PFMEA): an analysis that focuses on process-related issues. It may be used, for example, to analyze the manufacturing and assembly process before it goes "on-line."

The DFMEA typically assumes that the product will be manufactured according to the specifications and attempts to identify and address problems with the design itself. The PFMEA typically assumes that the design is sound and attempts to identify and address problems resulting from the manufacturing process.

For Design FMEAs, it is also common for practitioners to classify the analysis as follows:

System FMEA: a high-level analysis of the entire system, which often focuses on interfaces and interactions among subsystems/components and between the system and the environment or customer.
Subsystem FMEA: an analysis of a specific subsystem within the larger system, which could be a detailed analysis of the entire assembly or a more high-level analysis that focuses on the interfaces and interactions among the components in the assembly.
Component FMEA: a detailed analysis of a particular component within the larger system or assembly.

In addition, there are many other terms that have been used to describe particular types of FMEA, such as machinery FMEA (a process FMEA focused on manufacturing equipment), service FMEA (a process FMEA focused on repair, support or other services provided to a customer), interface FMEA (a design FMEA focused on the interfaces between assemblies), Software FMEA (a design FMEA focused on software) and FMECA (an FMEA that uses Criticality Analysis as the method of risk assessment).

Published Guidelines and Standards

Many industries and companies have developed their own particular procedures for FMEA, including the style of the analysis worksheet, the rating scales used for risk assessment and other details. Some of the major published standards include:

SAE J1739 for the automotive industry
AIAG FMEA and APQP for the automotive industry
ISO 16949 quality guidelines for the automotive industry
MIL-STD-1629A (cancelled in November, 1984 but still used in some military and other applications)
IEC 60812 from the International Electrotechnical Commission
ISO 14971 for the medical devices industry