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To be competitive, organizations must continually improve. Potential failure mode and effects analysis (FMEA) is a technique that offers a methodology to facilitate process improvement. Using FMEAs, organizations can identify and eliminate concerns early in the development of a proess or design. The quality of procurred parts or services canimprove when organizations workwith their suppliers to implement FMEAs within their organization. Properly executed FMEAs can improve internal and external customer satisfaction in addition to the bottom line of the organization.

This discussion focuses on design and process FMEAs. Design FMEA applications include component, subsystem, and main system. Process FMEA applications include assembly machines, work stations, gauges, procurement, training of operators, and tests.

Benefits of a properly executed FMEA include:

• Improved product functionality and robustness
• Reduced warranty costs
• Reduced day-to-day manufacturing problems
• Improved safety of products and implementation processes
• Reduced business process problems

Implementation

Timeliness and usefulness as a living document are important aspects of a successful FMEA. To achieve the maximum benefit, organizations need to conduct FMEAs before a failure is unknowingly instituted into a process or design.
FMEA input is a team effort; however, one individual typically is responsible by necessity, for its preparation. It is the role of the responsible engineer to avail of active involvement of representatives from all affected areas. FMEAs should be a part of design or process concept finalization that acts as a catalyst for the stimulation and interchange of ideas between functions. FMEAs should be a living document that is updated for design changes and the addition of new information.
Important FMEA implementation issues include the following:

• Use as a living document with periodic review and updates.
• Conduct early enough in development cycle to:
- design-out potential failure modes by eliminating root causes
- reduce seriousness of failure mode if elimination is not possible
- reduce the occurrence of the failure mode.

Implementation benefits of a FMEA include the following:

• Early actions in the design cycle saves time and money.
• Thorough analysis with teams creates better designs and processes.
• Complete analysis provides possible legal evidence.
• Previous FMEAs provide knowledge leading to current design or product FMEAs

Team interaction is important when executing an FMEA. organizations should consider using outside suppliers within an FMEA and creating the team so that it consists of five to seven knowledgeable, actve members. When executing an FMEA, teams work to identify possible failure modes for design functions or process requirements. They then assign a severity to the effect of this failure mode. they also assign a frequency of occurrence to the potential cause of failure and likelihood of detection. Organizations can differ in their approach to assign magnitudes to these assigned numbers (i.e., Severity, frequency of Occurrence, and likelihood of Detection - sometimes called SOD values) with the restriction that higher numbers are worse. After these numbers are determined, teams calculate a risk priority number (RPN), which is the product of these three numbers. Teams use the ranking of RPNs to focus on process improvement efforts.
An effective road map to create FMEA entries is as follows:

• Note an input to a process or design (e.g., process step, key input identified in a cause-and-effect matrix, or design function).
• List two or three ways input/function can go wrong.
• List at lease one effect of failure.
• For each failure mode list one or more causes of input going wrong.
• For each cause list at least one method of preventing or detecting cause.
• Enter SOD values.

Even though there are many different types and standards, most FMEAs consist of a common set of procedures. In general, FMEA analysis is conducted by a cross-functional team at various stages of the design, development, and manufacturing process and typically consists of the following:

• Current Controls: Examine the control mechanisms that will be in place to eliminate or mitigate the probability that the potential failures will occur (e.g. end of line inspections, design reviews, etc.).
• Failures: Identify the known and potential failures that could prevent or degrade the ability of the item/process to perform its designated functions.
• Failure Causes: Identify the known and potential causes for each failure.
• Failure Effects: Identify the known and potential effects that would result from the occurrence of each failure. It may be desirable to consider the effects at the item level (local effects), at the next higher level assembly (next higher level effects) and/or at the system level (end effects).
• Functions: Identify the functions that the item or process is expected to perform.
• Item/Process: Identify the item or process that will be the subject of the analysis, including some investigation into the design and reliability characteristics. For FMEA analysis of a product or system, the analysis could be performed at the system, subsystem, component or other level of the system configuration.
• Other Details: Depending on the particular situation and on the analysis guidelines adopted by the organization, other details may be considered during the analysis, such as the operational mode when the failure occurs or the system’s intended mission.
• Prioritize Issues: Prioritize issues for corrective action according to a consistent standard that has been established by the organization. Risk Priority Number (RPN) ratings and Criticality Analysis are common methods of prioritization and they are described in more detail later in this article.
• Recommended Actions: Identify the corrective actions that need to be taken in order to eliminate or mitigate the risk and then follow up on the completion of those recommended actions.
• Report: Generate a report of the analysis in the standard format that has been established by the organization. This is generally a tabular format. In addition, the report may include block diagrams and/or process flow diagrams to illustrate the item or process that is the subject of the analysis. If applicable, the criticality analysis may be included in a separate table and various plots/graphs can be included to display statistics on the modes and rankings.

In an upcoming issue we will discuss the development of a design FMEA.

Further Reading Recommended: Implementing Six Sigma, Forrest W. Breyfogle - Smarter Solutions, Inc, TX