Benefits of FMEA

Review Requiremen

ts

Changes Proposed?

Design Detail

Start

Get System requirements

Corrective Action required

Functional Block diagram

Determine Failure Mode

Severity

Occurrence

Detection

Team Review

FMEA Work Sheet

Review FRACAS Data

No changes required

Distribute to users

DesignEngineer

Technical Support

Manufacturing

Reliable Equipments

FMEA Prerequisites

Functional Block Diagram

Team Review

Functional Mode Analysis and preparation of worksheets

Corrective Action

Figure 1.FMEA Process

Benefits of FMEA

FMEA is designed to assist the engineer improve the quality and reliability

of design. Properly used the FMEA provides the engineer several benefits.

Among others, these benefits include:

Improve product/process reliability and quality

Increase customer satisfaction

Early identification and elimination of potential product/process failure

modes

Prioritize product/process deficiencies

Capture engineering/organization knowledge

Emphasizes problem prevention

Documents risk and actions taken to reduce risk

Provide focus for improved testing and development

Minimizes late changes and associated cost

Catalyst for teamwork and idea exchange between functions

Team for conducting/reviewing an FMEA

– Project Manager

– Design Engineer (hardware/software/systems)

– Test Engineer

– Reliability Engineer

– Quality Engineer

– Field Service Engineer

– Manufacturing/Process Engineer

– Safety Engineering

Outside supplier engineering and/or manufacturing could be added to the team.

Customer representation is recommended if a joint development program

between user/supplier exists.

PURPOSE OF FMEA

The purpose of performing an FMEA is to analyze the product's design

characteristics relative to the planned manufacturing process and experiment

design to ensure that the resultant product meets customer needs and

expectations. When potential failure modes are identified, corrective action can

be taken to eliminate them or to continually reduce a potential occurrence. The

FMEA also documents the rationale for the chosen manufacturing process. It

provides for an organized critical analysis of potential failure modes and the

associated causes for the system being defined. The technique uses occurrence

and detection probabilities in conjunction with severity criteria to develop a risk

priority number (RPN) for ranking corrective action considerations.

FMEA's provide the engineer with a tool that can assist in providing reliable, safe,

and customer pleasing products and processes. Since FMEA help the engineer

identify potential product or process failures, they can use it to:

Develop product or process requirements that minimize the likelihood of

those failures.

Evaluate the requirements obtained from the customer or other

participants in the design process to ensure that those requirements do

not introduce potential failures.

Identify design characteristics that contribute to failures and design them

out of the system or at least minimize the resulting effects.

Develop methods and procedures to develop and test the product/process

to ensure that the failures have been successfully eliminated.

Track and manage potential risks in the design. Tracking the risks

contributes to the development of corporate memory and the success of

future products as well.

Ensure that any failures that could occur will not injure or seriously impact

the customer of the product/process.

Failure Modes and Effects Analysis [FMEA]

Introduction

Customers are placing increased demands on companies for high quality,

reliable products. The increasing capabilities and functionality of many products

are making it more difficult for manufacturers to maintain the quality and

reliability. Traditionally, reliability has been achieved through extensive testing

and use of techniques such as probabilistic reliability modeling. These are

techniques done in the late stages of development. The challenge is to design in

quality and reliability early in the development cycle.

Failure Modes and Effects Analysis (FMEA) is methodology for analyzing

potential reliability problems early in the development cycle where it is easier to

take actions to overcome these issues, thereby enhancing reliability through

design. FMEA is used to identify potential failure modes, determine their effect on

the operation of the product, and identify actions to mitigate the failures. A crucial

step is anticipating what might go wrong with a product. While anticipating every

failure mode is not possible, the development team should formulate as

extensive a list of potential failure modes as possible.

The early and consistent use of FMEAs in the design process allows the

engineer to design out failures and produce reliable, safe, and customer pleasing

products. FMEAs also capture historical information for use in future product

improvement.

TYPES OF FMEA'S

There are several types of FMEAs, some are used much more often than

others. FMEAs should always be done whenever failures would mean potential

harm or injury to the user of the end item being designed. The types of FMEA

are:

System - focuses on global system functions

Design - focuses on components and subsystems

Process - focuses on manufacturing and assembly processes

Service - focuses on service functions

Software - focuses on software functions

System FMEA

This is used to analyze systems and subsystems in the early concept and

design stage. A system FMEA focuses on potential failure modes between the

functions of the system caused by system deficiencies. It includes the

interactions between systems and elements of the system.

The outputs of the system FMEA are

A potential list of failure modes ranked by RPN.

A potential list of system functions that could detect potential failure

modes.

A potential list of design actions to eliminate failure modes, safety issues

and reduces the occurrence.

The benefits of the system FEMA are that it: -

Helps to select the optimum system alternative.

Helps to determine redundancy.

Helps to define the basis for system level diagnostic procedures.

Increases the likelihood that potential problems will be considered.

Identifies potential system failures and their interaction with other systems.

Design FMEA

This is used to analyze products before they are released to

manufacturing. A design focuses on failure modes caused by design

deficiencies.

The outputs of the design FMEA are: -


A potential list of critical and / or significant characteristics.

A potential list of design actions to eliminate failure modes, safety issues

and reduces the occurrence.

A potential list of parameters for appropriate testing, inspection, and / or

detection methods.

A potential list of recommended action for the critical and significant

characteristics.

The benefits of design FMEA are that it: -

Establishes a priority for design improvement actions.

Documents the rationale for changes.

Provides information to help through design verification and testing.

Helps to identify the critical or significant characteristics.

Assists in the evaluation of design requirements and alternatives.

Helps to identify and eliminate potential safety concerns.

Helps to identify product failure early in the product development phase.

Process FMEA

This is used to analyze manufacturing and assembly processes. A

process FMEA focuses on failure modes caused by process or assembly

deficiencies.

The outputs of the process FMEA are: -


A potential list of critical and/ or significant characteristics.

A potential list of recommended actions to address the critical and

significant characteristics.

A potential list to eliminate the causes of failure modes, reduce their

occurrences, and improve defect detection if CPK cannot be improved.

The benefits of the process FMEA are that it: -

Identifies process deficiencies and offers a corrective action plan.

Identifies the critical and/ or significant characteristics and helps in

developing control plans.

Establishes a priority of corrective actions.

Assists in the analysis of the manufacturing or assembly process.


Service FMEA

This is used to analyze services before they reach the customer. A service

FMEA focuses on the failure modes (tasks, errors, mistakes) caused by

system or process deficiencies.

The outputs of the service FMEA are: -

A potential list of errors ranked by RPN.

A potential list of critical or significant tasks, or processes.

A potential list of bottleneck processes or tasks.

A potential list to eliminate the errors.

A potential list of monitoring system / process functions.

The benefits of the service FMEA are that it: -

Assists in the analysis of job flow.

Assists in the analysis of the system and/ or process.

Identifies task deficiencies.

Identifies critical or significant tasks and helps in the development of

control plan.

Establishes a priority for improvement actions.


An FMEA program should start

When new systems, designs, products, processes, or services are

designed.

When existing systems, designs, products, processes, or services are

about to change regardless of reason.

When new applications are found the existing conditions of the systems,

designs, products, processes, or service.

When improvements are considered for the existing systems, designs,

products, processes, or services.

FMEA PROCEDURE

1. Describe the product/process and its function

2. Create a Block Diagram of the product or process

3. Complete the header on the FMEA Form worksheet

4. Use the diagram prepared above to begin listing items or functions

5. Identify Failure Modes

6. Each failure should be listed in technical terms

7. Describe the effects of those failure modes

8. Identify the causes for each failure mode

9. Enter the Probability factor

10. Identify Current Controls (design or process)

11.Determine the likelihood of Detection

12.Review Risk Priority Numbers (RPN). RPN = (Severity) x (Probability) x

(Detection)

13.Determine Recommended Action(s) to address potential failures that have

a high RPN

14.Assign Responsibility and a Target Completion Date for these actions

15. Indicate Actions Taken

16.Update the FMEA as the design or process changes, the assessment

changes or new information becomes known.