FMEA

14.1 Introduction to FMEA

A Failure Modes Effect Analysis (FMEA) is an extremely powerful tool that all people can and
will benefit from no matter your occupation or status in life.
In this chapter, we shall discuss the history of the FMEA, the different types of FMEA, and finally
how to actually construct FMEA.
History
The FMEA is not a new tool. Begun in the 1940s by the U.S. military, FMEA was further
developed by the aerospace and automotive industries. Several industries maintain formal FMEA
standards. The aerospace industry used the FMEA during the Apollo missions in the 1960s. Later in
1974 the US Navy developed MIL-STD-1629 which discussed the proper use of the tool. And around
this time the automotive folks latched onto the tool and never let go. Today, the FMEA is universally
used by many different industries.

14.2 What is Failure Modes and Effects Analysis (FMEA)

It is also called potential failure modes and effects analysis or failure modes, effects and criticality
analysis (FMECA).
Failure Mode
“Failure modes” means the ways, or modes, in which something might fail. Failures are any
errors or defects, especially ones that affect the customer, and can be potential or actual. The manner in
which the product/part or service does not meet the customer’s expectations
Effects Analysis
“Effects analysis” refers to studying the consequences of those failures. A study of the effects of
failure on the function or purpose of the product/part or service
Failure modes and effects analysis (FMEA) is a step-by-step approach for identifying all possible
failures in a design, a manufacturing or assembly process, or a product or service.
Failures are prioritized according to how serious their consequences are, how frequently
they occur and how easily they can be detected. The purpose of the FMEA is to take actions to
eliminate or reduce failures, starting with the highest-priority ones.
The customer could be external to the company, or internal (within the company). It is
considered a reliability planning tool, but it has also become a method for prioritizing
alternative actions (that do not deal with failure modes), e.g., in the Six Sigma process.
Failure modes and effects analysis also documents current knowledge and actions about the risks
of failures, for use in continuous improvement. FMEA is used during design to prevent failures. Later
it’s used for control, before and during ongoing operation of the process. Ideally, FMEA begins during
the earliest conceptual stages of design and continues throughout the life of the product or service. A
completed FMEA, which should be applied in an iterative process, contains a great deal of information
about the product or process.
Before undertaking an FMEA process, learn more about standards and specific methods in your
organization and industry through other references and training.
Objectives of FMEA
• Recognize and evaluate the potential failure modes and causes associated with the designing and
manufacturing of a product
• Identify actions which could eliminate or reduce the chance of the potential failure occurring
• Document the above process.
Benefits of FMEA
• Prevention Planning
• Identifies change requirements
• Cost reduction
• Increased throughput
• Decreased waste
• Decreased warranty costs
• Reduce non-value added operations
• It increases the likelihood that potential failures, and their effects and causes, will be considered
prior to the final design and/or release to production.
• To plan preventive actions.
• It can be used as the starting point for later control plans, trouble-shooting guides, preventive
maintenance plans, etc.
When to Use FMEA
• When a process, product or service is being designed or redesigned, after quality function
deployment.
• When an existing process, product or service is being applied in a new way.
• Before developing control plans for a new or modified process.
• When improvement goals are planned for an existing process, product or service.
• When analyzing failures of an existing process, product or service.
• Periodically throughout the life of the process, product or service

Types of FMEA
There are three main types of FMEA in use today.
1. Concept FMEA: It is used to analyze complete systems and/or sub-systems during the concept
of design stage.
2. Process FMEA: It is used to analyze manufacturing and/or assembly process.
3. Design FMEA: It is used the analyze a product design before it is released to manufacturing.

14.3 FMEA Procedure

Before understanding FMEA procedure it is important to understand the concept of Risk Priority
Number (RPN).

Examining Risk Priority Numbers in FMEA

 The Risk Priority Number (RPN) methodology is a technique for analyzing the risk associated with
potential problems identified during a Failure Mode and Effects Analysis (FMEA). This article presents
a brief overview of the basic RPN method and then examines some additional and alternative ways to
use RPN ratings to evaluate the risk associated with a product or process design and to prioritize
problems for corrective action. Note that this Chapter discusses RPNs calculated at the level of the
potential causes of failure (Severity x Occurrence x Detection). However, there is a great deal of
variation among FMEA practitioners as to the specific analysis procedure and some analyses may
include alternative calculation methods.

Overview of Risk Priority Numbers

An FMEA can be performed to identify the potential failure modes for a product or process. The RPN
method then requires the analysis team to use past experience and engineering judgment to rate
each potential problem according to three rating scales:

• Severity, which rates the severity of the potential effect of the failure.
• Occurrence, which rates the likelihood that the failure will occur.
• Detection, which rates the likelihood that the problem will be detected before it reaches the end-
user/customer.

Rating scales usually range from 1 to 5 or from 1 to 10, with the higher number representing the higher
seriousness or risk. For example, on a ten point Occurrence scale, 10 indicates that the failure is very
likely to occur and is worse than 1, which indicates that the failure is very unlikely to occur. The specific
rating descriptions and criteria are defined by the organization or the analysis team to fit the products
or processes that are being analyzed. As an example, Figure 1 shows a generic five point scale for
Severity [Stamatis, 445].
 Figure 14.1: Generic five point Severity scale

After the ratings have been assigned, the RPN for each issue is calculated by multiplying Severity x
Occurrence x Detection.

The RPN value for each potential problem can then be used to compare the issues identified within
the analysis. Typically, if the RPN falls within a pre-determined range, corrective action may be
recommended or required to reduce the risk (i.e. to reduce the likelihood of occurrence, increase the
likelihood of prior detection or, if possible, reduce the severity of the failure effect). When using this
risk assessment technique, it is important to remember that RPN ratings are relative to a particular
analysis (performed with a common set of rating scales and an analysis team that strives to make
consistent rating assignments for all issues identified within the analysis). Therefore, an RPN in one
analysis is comparable to other RPNs in the same analysis but it may not be comparable to RPNs in
another analysis.

Let us understand general procedure of FMEA. Specific details may vary with standards of your
organization or industry.
1. Assemble a cross-functional team of people with diverse knowledge about the process, product
or service and customer needs. Functions often included are: design, manufacturing, quality,
testing, reliability, maintenance, purchasing (and suppliers), sales, marketing (and customers)
and customer service.
2. Identify the scope of the FMEA. Is it for concept, system, design, process or service? What are
the boundaries? How detailed should we be? Use flowcharts to identify the scope and to make
sure every team member understands it in detail. (From here on, we’ll use the word “scope” to
mean the system, design, process or service that is the subject of your FMEA.)
3. Fill in the identifying information at the top of your FMEA form. Figure 1 shows a typical format.
The remaining steps ask for information that will go into the columns of the form.
4. Identify the functions of your scope. Ask, “What is the purpose of this system, design, process or
service? What do our customers expect it to do?” Name it with a verb followed by a noun. Usually
you will break the scope into separate subsystems, items, parts, assemblies or process steps and
identify the function of each.
5. For each function, identify all the ways failure could happen. These are potential failure modes.
If necessary, go back and rewrite the function with more detail to be sure the failure modes show
a loss of that function.
6. For each failure mode, identify all the consequences on the system, related systems, process,
related processes, product, service, customer or regulations. These are potential effects of failure.
Ask, “What does the customer experience because of this failure? What happens when this failure
occurs?”
7. Determine how serious each effect is. This is the severity rating, or S. Severity is usually rated
on a scale from 1 to 10, where 1 is insignificant and 10 is catastrophic. If a failure mode has more
than one effect, write on the FMEA table only the highest severity rating for that failure mode.
8. For each failure mode, determine all the potential root causes. Use tools classified as cause
analysis tool, as well as the best knowledge and experience of the team. List all possible causes
for each failure mode on the FMEA form.
9. For each cause, determine the occurrence rating, or O. This rating estimates the probability of
failure occurring for that reason during the lifetime of your scope. Occurrence is usually rated on
a scale from 1 to 10, where 1 is extremely unlikely and 10 is inevitable. On the FMEA table, list
the occurrence rating for each cause.
10. For each cause, identify current process controls. These are tests, procedures or mechanisms that
you now have in place to keep failures from reaching the customer. These controls might prevent
the cause from happening, reduce the likelihood that it will happen or detect failure after the
cause has already happened but before the customer is affected.
11. For each control, determine the detection rating, or D. This rating estimates how well the controls
can detect either the cause or its failure mode after they have happened but before the customer
is affected. Detection is usually rated on a scale from 1 to 10, where 1 means the control is
absolutely certain to detect the problem and 10 means the control is certain not to detect the
problem (or no control exists). On the FMEA table, list the detection rating for each cause.
12. (Optional for most industries) Is this failure mode associated with a critical characteristic?
(Critical characteristics are measurements or indicators that reflect safety or compliance with
government regulations and need special controls.) If so, a column labeled “Classification”
receives a Y or N to show whether special controls are needed. Usually, critical characteristics
have a severity of 9 or 10 and occurrence and detection ratings above 3.
13. Calculate the risk priority number, or RPN, which equals S × O × D. Also calculate Criticality
by multiplying severity by occurrence, S × O. These numbers provide guidance for ranking
potential failures in the order they should be addressed.
14. Identify recommended actions. These actions may be design or process changes to lower severity
or occurrence. They may be additional controls to improve detection. Also note who is
responsible for the actions and target completion dates.
15. As actions are completed, note results and the date on the FMEA form. Also, note new S, O or
D ratings and new RPNs.
The Process FMEA is probably the most commonly used and is also the least complex, in most
cases.

14.4 Concept FMEA

This type of FMEA includes the interaction of multiple systems and interaction between the
elements of a system at the concept stages. In the System interactions between the systems and the
elements of the systems, FMEA examines system deficiencies caused by potential failure modes
between the functions of the system.
Objectives of Concept FMEA
• The Concept FMEA is used to analyze concepts in the early stages before hardware is defined
(most often at system and subsystem).
• It focuses on potential failure modes associated with the proposed functions of a concept
proposal.
Benefits of Concept FMEA
• Helps select the optimum concept alternatives, or determine changes to design specifications
• Identifies potential failure modes caused by interactions within the concept
• Increases the likelihood all potential effects of a proposed concept’s failure modes are considered.
• Identifies system level testing requirements
• Helps determine if hardware system redundancy may be required within a design proposal

14.5 Process FMEA

The Process FMEA is normally used to analyze manufacturing and assembly processes at the
system, subsystem or component levels. This type of FMEA focuses on potential failure modes of the
process that are caused by manufacturing or assembly process deficiencies.
Process FMEA Objectives
• Maximize system quality, reliability, & productivity
• Minimize production process - based failure effects on the system
• Minimize variation around the design specs due to the process
Benefits of Process FMEA
• Identifies potential product related process failure modes.
• Assesses the potential customer effects of the failures.
• Identifies the potential manufacturing or assembly process causes and identifies process
variables on which to focus controls or monitoring.
• Develops a ranked list of potential failure modes, establishing a priority system for corrective
action considerations.
• Documents the results of the manufacturing or assembly process.
• Identifies process deficiencies
• Identifies confirmed critical characteristics and/or significant characteristics
• Identifies operator safety concerns
• Feeds information on design changes required and manufacturing feasibility back to the
designers.
Ten steps to creating a Process FMEA
1. List the key process steps in the first column. These may come from the highest ranked items
of your Cause & Effect matrix.
2. List the potential failure mode for each process step. In other words, figure out how this
process step or input could go wrong.
3. List the effects of this failure mode. If the failure mode occurs what does this mean to us and
our customer… in short what is the effect?
4. Rate how severe this effect is with 1 being not severe at all and 10 being extremely severe.
Ensure the team understands and agrees to the scale before you start. Also, make this ranking
system “your own” and don’t bother trying to copy it out of a book.
5. Identify the causes of the failure mode/effect and rank it as you did the effects in the occurrence
column. This time, as the name implies, we are scoring how likely this cause will occur. So, 1
means it is highly unlikely to ever occur and 10 means we expect it to happen all the time.
6. Identify the controls in place to detect the issue and rank its effectiveness in the detection
column. Here a score of 1 would mean we have excellent controls and 10 would mean we have
no controls or extremely weak controls. If a SOP is noted here (a weak control in my opinion)
you should note the SOP number.
7. Multiply the severity, occurrence, and detection numbers and store this value in the RPN (risk
priority number) column. This is the key number that will be used to identify where the team
should focus first. If, for example, we had a severity of 10 (very severe), occurrence of 10
(happens all the time), and detection of 10 (cannot detect it) our RPN is 1000. This means all
hands on deck… we have a serious issue!
8. Sort by RPN number and identify most critical issues. The team must decide where to focus
first.
9. Assign specific actions with responsible persons. Also, be sure to include the date for when
this action is expected to be complete.
10. Once actions have been completed, re-score the occurrence and detection. In most cases we
will not change the severity score unless the customer decides this is not an important issue.

14.6 Design FMEA

The Design FMEA is used to analyze products before they are released to production. It focuses
on potential failure modes of products caused by design deficiencies. Design FMEAs are normally done
at three levels – system, subsystem, and component levels. This type of FMEA is used to analyze
hardware, functions or a combination. At the Design FMEA level, it is usually recommended to study
each subsystem separately, and each component separately.
Objectives of Design FMEA
• Maximize system quality and reliability
• Minimize design-based failure effects on the system
• To take into account Design for Manufacturability or Design for Assembly principles
Benefits Design FMEA
• Aids in the objective evaluation of design requirements and design alternatives
• Aids in the initial design for manufacturing and assembly requirements
• Increases the probability that potential failure modes and their effects have been considered in
the design/development process
• Provides additional information to help plan thorough and efficient test programs.
• Develops a list of potential failure modes ranked according to their effect on the customer.
Establishes a priority system for design improvements.
• Provides an open issue format for recommending and tracking risk reducing actions.
• Provides future reference to aid in analyzing field concerns.

14.7 Differences between Design FMEA and Process FMEA

The key difference in the objectives between the two is the focus of the FMEA.
 When conducting a Design FMEA, the team must remember to think in terms of the causes and
effects of failure modes due to the design itself. The causes usually involve product design variables
that can be specified by the design team. Design for Manufacturability /Assembly and all other
considerations should be included in the Design FMEA e.g., tooling access, robustness to sources of
process variation, ability of product to be produced at planned production rates, maintainability, etc.

In a Process FMEA, the team will be focused on those failure modes and causes that could result
from the production or service process itself rather than from the design of the product.

14.8 FMEA Implementation Stages

Organizations that use FMEAs can normally be categorized in one of five implementation stages.
Organizations that achieve measurable monetary benefits operate in stages four or five. Unfortunately,
most organizations remain in stages one through three, with most in stage one.
Stage 1 : Poor FMEA Understanding
Typically the organization in stage one uses FMEAs because it has to meet a paper requirement
for a customer or quality standard. Personnel perform the FMEA right before it is due to be turned in to
the customer, usually too late in the process to be useful.
Quite often, the wrong people perform the FMEA. The quality department ends up developing
the documents rather than making design engineers responsible for design FMEAs and operating
personnel responsible for process FMEAs.
Management does not understand the FMEA, and a lot of confusion and disagreement exists as
to how to fill out the FMEA form. Debate occurs when individuals attempt to develop the ratings for
occurrence and detection numbers. Because accurate feedback systems don't yet exist to base the ratings
on, they're based on inaccurate guesses. Using inaccurate ratings , the organization calculates erroneous
RPNs and identifies an RPN level at which recommended actions are needed. If the number of
recommended actions required based on this level is too high, the organization "adjusts" the ratings to
bring the RPNs down below the trigger level, which reduces the number of recommended actions.
Obviously, this makes the entire FMEA process meaningless.
As a result, the organization fulfills its paper requirement, but the value of the FMEA is greatly
diminished. Problems still remain unsolved at a high cost to the organization. The individuals
performing the FMEAs believe they are doing them correctly because the customer or auditor is
accepting them. Eventually, everyone sees the FMEA process not as a tool but as something that has to
be done.
Stage 2 : Learning Proper FMEA Techniques
Management ensures that the personnel who will perform and use the FMEA data are trained in
the proper technique. They realize that the people who perform design FMEAs must be experts in the
product and the people who perform the process FMEAs must be experts in the process. Rather than
being confused by the FMEA terminology, they realize they have used the FMEA methodology before
but never called it FMEA. They also learn that although they have used the methodology, they have not
used it rigorously enough to achieve its full benefits. In stage two, everyone involved gains an
understanding of what the ratings and class column mean and how to use them to prioritize what must
be worked on first. They understand that the class column is the most important factor and not the RPN.
Management also realized that they don't have systems in place that will give them data to accurately
determine the failure probability occurrence ratings, detection ratings and class. Using the limited
objective data they have, they know they will have to use their knowledge of the product and process
to arrive at the ratings. Due to the lack of an objective basis, they know that it is a waste of time to argue
for long periods about the ratings.
When leaving this stage, those who have been using FMEAs believe they can be a powerful tool.
Unfortunately, the people who perform FMEAs doubt whether management will provide the time and
resources necessary to support their successful implementation. They also question how they will
explain the new approach to their auditor or customer, who may still be at stage one in their
understanding of the FMEA implementation process.
Stage 3 : Building a Proper FMEA
The organization begins to use FMEAs correctly on a targeted product. Early on there is
excitement that the FMEAs are finally going to be done correctly. As the implementation continues,
worry starts to set in as the FMEA uncovers and documents the complexity of the product and process
being analyzed. Everyone knew the complexity existed but had never seen it documented. The FMEA
grows from the 5 or 10 pages that used to be normal to 100 or more pages. The organization must
overcome its fear of the increased length and complexity of the complete FMEA if FMEAs are to be
used successfully.
As the FMEA process continues, many problems may be uncovered that must be solved if the
company is to become as good as it can be. There may not be enough resources to solve all of these
problems and still meet the launch deadline.
Knowing this, people begin to proclaim that FMEAs will never work. They believe that all the
hard work has been a waste of time. What good is it to know what is wrong and not be able to correct
it? Life was a lot easier when all the problems were not documented. If organizations don't overcome
this obstacle they may slip back into stage one.
Stage 4 : Using a FMEA's Outputs
Management realizes that the length of a FMEA cannot be predetermined. The complexity of the
product and process being analyzed determines the FMEA's length. Management understands that all
of the problems uncovered in the FMEA can't be solved in one product launch. They understand that
the product will be launched with known problems and that they will have to make objective decisions
as to what to work on during this launch and what must be delayed. When a problem occurs in an area
that management decided not to work on, it is handled without emotion. This is possible because the
FMEA identified that it might happen and management chose not to work on it so that other problems
could be prevented.Once the organization launches the product, management creates a long-term plan
to improve the design and manufacturing systems. This plan minimizes the times the company must
make difficult decisions when doing FMEAs in the future.
Stage 5 : Full FMEA Implementation and Integration
The organization has implemented new design and manufacturing systems to answer the majority
of the problems identified in the FMEAs. Systems now exist to provide data to accurately set occurrence
and detection ratings. Due to the accuracy of the new ratings, predictions about field failures and process
yields can be made. The class column can now be accurately determined and actions required for
improvement prioritized.
Design engineers review design FMEAs before making design changes. If a change must
 be made, operating personnel review the process FMEA and control plan to determine the impact
the change will have on the process.
When a problem occurs, the appropriate personnel consult the FMEAs. If the FMEA inadequately
addressed the problem, engineers make changes to the design and manufacturing system to ensure that
all possible steps have been taken to prevent a similar problem in the future. The organization uses the
FMEAs as training tools because they contain the collective knowledge of the company's experts.
14.9 Reasons of why FMEAs fail

1. One person is assigned to do the FMEA alone.

2. Not customizing the three rating scales with company specific examples so that they are
meaningful to your company.
3. The design or process expert is either not included on the FMEA team or is allowed to
dominate the FMEA team.
4. Members of the FMEA team have not been properly trained in the use of FMEAs and
become frustrated with the process.
5. The FMEA team gets bogged down with the minute details of the design or process,
losing sight of the overall objective.
6. Rushing through the generation of potential failure modes in a hurry to move on to the
next step of the FMEA, possibly overlooking significant but obscure failure modes.
7. Listing practically the same effect for every failure mode and not being more specific (for
example "customer will be unhappy").
8. Stopping once the RPNs are calculated and not taking action on the highest risk failures.
9. Not re-evaluating the RPNs once improvements have been made to assess the impact of
the improvements.

14.10 Please refer sample FMEA Template along with example

This FMEA example regarding managerial process is good enough to explain how FMEA is
used in practice. Those with higher RPN, action should be taken first.

Potential Potential Current Recommended

Process Step SEV Potential Causes OCC DET RPN Responsibility
Failure Modes Failure Effects Controls Action

Work with
Reps not in the Manager country headr and
Reduced
office for No time control controls IT head to have a
Time control capacity. 9 4 3 108 Div Manager
specified hours tools without time control tool
Backlog created
or wasting time any tool as early as
possible

Reps not
Work with
coming to work Reduced Illness
No motivation for country head and
Absenteeism because of capacity. 9 6 certificatio 9 486 Div Manager
good attendance HR to implement
suspicious Backlog created n required
variable payment
illness

Loosing Reduced Counter

High skilled reps,
experience reps capacity due to offer in No Action
Attrition 3 better offers in 3 1 9
and having high new hires on certain Required
the market
rotation rate training cases

Reps do not
Management to
clearly know Department Management
Targets not calculate targets
what is targets not 9 delays to provide 9 No control 1 81 Div Manager
defined and communicate
expected from reached calculate targets
them to reps
them
 Work with HR to
Implement
variable payment.
Reps not Reduced
Inefficient and good
working at their capacity,
Motivation 9 incentive 4 No control 4 144 implementation Div Manager
highest backlog created,
program of recognition
potential bad quality
program, improve
management
communication

Reps don't
know what
management Low motivation,
Inefficient
Communica- expect from department No Action
3 communication 3 No control 3 27
tion process them and don't targets not Required
process
have clear reached
understanding
of processes

Auditors providing
No trainers training to process
Experience reps
Training Reduced available from staff. Escalate to
providing 9 9 No control 1 81 Div Manager
process capacity training country head to
training
department have a dedicated
trainer

Manager
Customer not reviews
Volumes Productivity No Action
Volumes 9 disconnecting 3 daily 1 27
decreased decreased Required
circuits volume
received

Reps are not Managers will

Low motivation,
recognized or Inefficient provide monthly
Evaluation department
corrected for 9 evaluation 4 No control 3 108 feedback on Sr Managers
process targets not
high or poor process performance to
reached
performance reps

Absenteeism,
SLA targets not
Orders are not reduced working
reached, No Action
Backlog completed on 9 time, unusual 3 No control 1 27
productivity Required
time high volume
reduced
received

Conclusion

The FMEA process can be a powerful tool when properly used. As with any tool, before it can
be used well it must be understood. Once organizations fully understand and commit to the FMEA
process, they may be pleasantly surprised with the money they save and the product and process
improvements that result.
One of the most important factors for the successful implementation of an FMEA program is
timeliness. Upfront time spent properly completing an FMEA well, when product/process changes can
be most easily and inexpensively implemented, will minimize late change crises.
When going through the FMEA process, it is also important to remember to base your decisions
on data, not on hunches! It should occur very early in the planning cycle. FMEA teams will find
themselves spending more time than usual early on, which will lead to leveraged savings later on.
The use of data to verify the relationships between root causes and effects, to establish accurate
rating criteria, and to determine effective preventive actions is one of the critical-to-success factors in
the FMEA process.