2. History of the FMEA
•• The FMEA discipline was developed in the United States
The FMEA discipline was developed in the United States
Military in 1949 (Military Procedure MIL-P-1629, titled
Military in 1949 (Military Procedure MIL-P-1629, titled
Procedures for Performing a Failure Mode, Effects and
Procedures for Performing a Failure Mode, Effects and
Criticality Analysis.
Criticality Analysis.
•• The first formal application of FMEA discipline was used in
The first formal application of FMEA discipline was used in
aerospace in mid 60s.
aerospace in mid 60s.
•• It was used as a reliability evaluation technique to determine
It was used as a reliability evaluation technique to determine
the effect of system and equipment failures. Failures were
the effect of system and equipment failures. Failures were
classified according to their impact on mission success and
classified according to their impact on mission success and
personnel/equipment safety.
personnel/equipment safety.
•• Reference: SAE JJ1739 and AIAG.
Reference: SAE 1739 and AIAG.
3. What is FMEA?
A structured approach to
A structured approach to
Identify the way in which a design // process can fail to meet
Identify the way in which a design process can fail to meet
critical customer requirements.
critical customer requirements.
Estimating the risk of specific causes with regard to the failures.
Estimating the risk of specific causes with regard to the failures.
Evaluating the Current control plan for preventing the failures from
Evaluating the Current control plan for preventing the failures from
occurring.
occurring.
Prioritizing the actions that should be taken to improve the design/
Prioritizing the actions that should be taken to improve the design/
process.
process.
4. When to use FMEA?
FMEA is very beneficial to conduct while designing a product or
FMEA is very beneficial to conduct while designing a product or
process.
process.
Design FMEA should be done during initial design of the product.
Design FMEA should be done during initial design of the product.
Process FMEA should be done during design of manufacturing
Process FMEA should be done during design of manufacturing
process.
process.
Process FMEA can be performed for legacy products and processes
Process FMEA can be performed for legacy products and processes
also ififthe process carry high risks to product quality, customer, safety,
also the process carry high risks to product quality, customer, safety,
etc.
etc.
5. Different Types of FMEA
Design FMEA Process FMEA
An analytical technique used An analytical technique used
primarily by design responsible primarily by manufacturing
engineer/Team to assure responsible engineer/Team to
potential failure modes; causes assure potential failure modes;
and effects have been causes and effects have been
addressed for design related addressed for process related
characteristics. characteristics.
System, Subsystem,
Component level FMEA are
possible scopes
6. Definitions
Criticality
The Criticality rating is the
Severity mathematical product of
the Severity and
Severity is an assessment of how serious the Occurrence ratings.
Effect of the potential Failure Mode is on the Criticality = (S) X (O). This
Customer. number is used to place
Critical Characteristics priority on items that
require additional quality
Critical Characteristics are Special planning.
Characteristics defined by
organization that affect customer Occurrence
safety and/or could result in non-
compliance with government Occurrence is an assessment of the likelihood
regulations and thus require special that a particular Cause will happen and result
controls to ensure 100% compliance. in the Failure Mode during the intended life and
use of the product.
Risk Priority Number
Detection
The Risk Priority Number is a
Detection is an assessment of the likelihood mathematical product of the
that the Current Controls (design and process) numerical Severity, Occurrence,
will detect the Cause of the Failure Mode or the and Detection ratings.
Failure Mode itself, thus preventing it from RPN = (S) X (O) X (D). This
reaching the Customer. number is used to place priority
on items than require additional
quality planning.
7. Definitions
Current Controls
FMEA Element Current Controls (design and process) are the
mechanisms that prevent the Cause of the
FMEA elements are identified or
Function analyzed in the FMEA process.
Failure Mode from occurring, or which detect
the failure before it reaches the Customer.
Common examples are Functions,
A Function could be any
Failure Modes, Causes, Effects,
intended purpose of a
Controls, and Actions. FMEA
product or process. FMEA
elements appear as column
functions are best
headings in the output form.
described in verb-noun
format with engineering
specifications.
Failure Mode Cause Effect
Failure Modes are sometimes described as A Cause is the means by An Effect is an adverse consequence that the
categories of failure. A potential Failure Mode which a particular element Customer might experience. The Customer
describes the way in which a product or of the design or process could be the next operation, subsequent
process could fail to perform its desired results in a Failure Mode. operations, or the end user.
function (design intent or performance
requirements) as described by the needs,
wants, and expectations of the internal and
external Customers.
Customer
Customers are internal and
external departments, people, and
processes that will be adversely
affected by product failure.
8. FMEA- A team based effort.
• Input is required from shop
floor-supervision through to
management.
• Engineering/ R & D
• Service.
• Reliability.
• Purchasing.
• Quality Engineering.
• Supplier Quality Engineering
• Manufacturing
• EH & S, ROHS
9. FMEA Traditional approach
Review design and process using a functional block diagram, system
design, architecture and process flow chart.
Use a brainstorming approach to gather potential failure modes.
Use historical data from customer returns, complaints and internal
issues from comparable products or processes.
List potential effects, both internal and external, of failure.
Assign severity, occurrence and detection (SOD) rankings based on
the effect, probability of occurrence of the root cause and ability to
detect the root cause before the failure mode happens.
Calculate the risk priority number (RPN) by multiplying severity,
occurrence and detection rankings. Also, calculate criticality by
multiplying severity and occurrence.
Prioritize the failure modes (risks) based on RPN score and/or
criticality.
Take actions to eliminate or reduce the risks.
10. TRADITIONAL
APPROACH FMEA
FMEA FMEA
FMEA
DEVELOPMENT
DEVELOPMENT TEAM
TEAM
PROCESS
PROCESS
Flow FMEA
FMEA
chart Forms
Forms
FMEA
FMEA Process
Process Prepared
Prepared
Owner
Owner Part No.
Part No. Due Date
Due Date
#
# I.D.
I.D. By
By
FMEA
FMEA Core
Core Process
Process Pot Failure
Pot Failure Failure
Failure Severity
Severity
DATE
DATE Team
Team Function
Function Mode
Mode Effects
Effects
Pot
Pot Current
Current
Class
Class Occurrence
Occurrence Detection
Detection
Causes
Causes Control
Control
11.
12. Major issues
• Quality of the FMEA
• Quantity of Completion
• Fundamental issues- Bundling
of causes!
• Fill it, Shut it, Forget it*!
* Courtesy: Famous 80s advertisement campaign from Hero Honda Motor cycle manufacturers India. (On fuel economy)
13. Pitfalls
During development:
Not understanding the fundamentals of failure mode effects analysis
(FMEA) development.
Inadequate representation in the team from subject matter experts.
Failing to identify the right inputs for the FMEA.
Poor planning before assembling for brainstorming and failure ranking.
During implementation:
Breaking the sessions into weekly meetings (thus losing continuity).
Using severity, occurrence and detection (SOD) scales that are not
representative of the industry, product family or process group.
Failing to learn from the risks exposed at the component and module-
level FMEA while drafting at the system level FMEA.
Allowing the rigor of the tool to drive the intensity of initial interactions,
causing fatigue for participants.
14. Pitfalls (Continued)
During implementation: (Continued)
Wasting time on risk-rating debates.
Failing to follow through on recommended actions.
Failing to drive actions across the board in a systemic way.
Failing to integrate the learning from design and process FMEAs or to link to
control plans, critical to quality characteristics and critical to process
parameters.
During sustainability:
Not incorporating the identified, mitigated risks into manufacturing
guidelines to be used for future product development.
Failure to keep the FMEA alive by including feedback from subsequent
stages of the product life cycle.
15.
16.
17.
18. Sources of data
Customer Returns- DPPM data
% Defective, Defects per Unit
Product Design related BODY OF KNOWLEDGE
E.g. Performance, reliability, etc. Process Control
Similar sources of data from comparable E.g. Out of Spec, Contamination
Process Design related Products, processes of Organization Supplier caused
E.g. Opportunity for error E.g. Out of Spec, non conformance, etc.
Process Control
E.g. Out of Spec, Contamination
Customer caused DFMEA / PFMEA
E.g. damage, S/W error, etc.
(Potential)
Supplier caused
Failure mode-Effects-Causes
E.g. Out of Spec, non conformance, etc.
Customer Complaints External Knowledge
Customer complaints on Known Industry failure
product or system performance -Technical journals, publications,
With No product return or RMA -Conferences, etc.
Internal Ongoing Reliability issues
Supplier feedback
Periodic Surveillance
E.g. Out of Spec Product/Process Design Related
E.g. tight unrealistic tolerances, Capability.
Product or Process Changes
E.g. failure, etc. Process control issues
E.g. traceability, yield, etc.
19. Scope Process (Process FMEA)
• Formulate Cross functional Team
• Understand Customer/Process Requirements.
• Define the start and end of the Process
• All team members to walk and observe the process.
• Get the assemblers/ process operators to explain the process.
• Team makes notes and observations.
20. Brainstorm all potential causes for the
failure modes
Inputs:
INNOVATIVE APPROACH Process Flow charts, Manufacturing WI,
Historical process defect pareto, lessons learned, Etc
23. Brainstorm all potential failure modes
• Utilize process flow chart-break down each step.
• Use knowledge of previous and existing parts/processes.
• Review all quality information E.g.: Scrap, rework, RMA,etc.
• Talk to internal and external customers.
Failure Mode Effect
Failure Modes are sometimes described as An Effect is an adverse consequence that the
categories of failure. A potential Failure Mode Customer might experience. The Customer
describes the way in which a product or could be the next operation, subsequent
process could fail to perform its desired operations, or the end user.
function (design intent or performance
requirements) as described by the needs,
wants, and expectations of the internal and Example:
external Customers. Does not fit, Cannot load or fasten, poor
performance, intermittent failure erratic
Example: operation.
Fiber Damage, Contamination, hairline crack,
Dimension oversize.
24. Identify potential effects of failure
For each failure mode, identify the effect(s)
on the current or next process or customer
downstream in manufacturing/assembly process.
Describe the effects of failure in terms of what the customer
might notice or experience.
25. Cause and Effect Cascade with an example
Cause = Corrosion
Design Cause Effect = High Resistance
Effect
Environmental Cause = High Resistance
Exposure Effect = Insufficient Current
Cause
Moisture Cause Cause = Insufficient Current
Effect
Effect Effect = Dim Bulb
Corrosion
Cause = Design
Cause
Effect = Env. Exposure Poor Contact
(High Cause
Cause = Env. Exposure Effect Resistance)
Effect
Effect = Moisture
Insufficient
Cause
Current
Cause = Moisture Effect
Effect = Corrosion Dim Bulb
Courtesy: Elsmar Cove
26. Determine severity rating
Severity is an assessment of the seriousness of
the effect of Potential failure mode to the customer.
Severity applies to effect only.
Note: Assigning severity rating should be performed as a team
Including customer representative and or Design FMEA engineer.
If the customer affected by a failure mode is a user outside the plant, team
Should consult them and assign the rating.
27. Identify all potential causes of failure
How the failure could occur? Describe in terms of factors
That can be corrected or controlled.
There could be more than one cause for each failure!!
Example:Improper torque, Inaccurate gauging, inadequate lubrication, etc.
Note: Experiments may have to be conducted to determine causes using technical
Problem solving.
Management should have control on the cause identified. The cause
should be at the root level.
28. Determine occurrence rating
Occurrence is how frequently the specific failure cause
Mechanism is projected to occur.
Define Current Controls
Systematic methods/devices in place to prevent or detect
Failure modes or causes (before the effect happens).
Example: Poke-Yoke, automated control for setup verification
Note: If available from a similar process, statistical data should be used to determine
Occurrence ranking.
29. Determine detection ranking
Detection is an assessment of the probability that the
current process control will detect a Potential cause.
Also assess the ability of the process control to detect
Low frequency failure modes or prevent from going
Into the next process.
Note: Random quality checks are unlikely to detect the existence of an isolated
Defect and should not influence the detection ranking. Sampling done on a
Statistical basis is a valid detection control.
30. Current Controls
Design and Process controls are grouped according to their purpose.
Type (1)
These controls prevent the Cause or Failure Mode from
occurring, or reduce their rate of occurrence.
Type (2)
These controls detect the Cause of the Failure Mode and
lead to corrective action.
Type (3)
These Controls detect the Failure Mode before the
product reaches the customer. The customer could be
the next operation, subsequent operations, or the end
user.
The distinction between controls that prevent failure (Type 1) and controls that detect failure (Types 2 and 3) is
important. Type 1 controls reduce the likelihood that a Cause or Failure Mode will occur, and therefore affect
Occurrence ratings. Type 2 and Type 3 Controls detect Causes and Failure Modes respectively, and therefore
affect Detection ratings.
31. Calculate the Risk Priority Numbers
The Risk Priority Number is the product of
Severity (S) X Occurrence (O) X Detection (D) rankings.
This value should be used to rank order the concerns
In the process using Pareto. The RPN will be
between 1and 1000.
Criticality is severity multiplied by occurrence.
This is also an important metric.
RPN can be reduced by improving the detection, but the
process issue may remain intact. Criticality can be
reduced only by improving the capability or redesign.
32. Prioritize Corrective actions
•Concentrate on the Highest RPN
•Do not lose sight on effects with high severity.
•Think of how the occurrence can be reduced?
•How the detection can be improved?
•Where applicable use Mistake proofing techniques.
•Introduce changes in a controlled manner.
33. Reassess rankings when action completed
• FMEA must be a Live document.
• Review Regularly.
• Reassess rankings whenever changes made to product/process.
• Add any new defects or potential problems when found.
34. References
• Potential Failure Mode & Effects Analysis, fourth edition,
Automotive Industry Action Group, 2008.
• Govindarajan “Govind” Ramu, “Metrics That Trigger
Actionable Discussions: Prioritize Process Improvements
Using Gauge R&R and SPC Capability,” ASQ Six Sigma
Forum.
• Traditionally, NGT is used to collect ideas:
www.asq.org/learn-about-quality/idea-creation-
tools/overview/nominal-group.html In FMEA development, it
can be used to collect scores of SOD.
• Elsmar Cove archived file references.
Bibliography
Quality Training Portal, Resource Engineering Inc., “What You Need to
Know About Failure Mode and Effects Analysis (FMEA),”
www.qualitytrainingportal.com/resources/fmea/index.htm.
May 2009 QP – Standards Outlook – Dan Reid- Major Upgrade.