Transcript ITED 434 11/2/2003

ITED 434
11/2/2003
Introduction to Failure
Modes and Effects Analysis
From: Failure Modes and Effects Analysis(FMEA), by Kenneth Crow, DRM Associates
http://www.npd-solutions.com/fmea.html
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John Dewey once said, "A problem
well-defined is half solved."
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Review of Function Analysis
Function Analysis is the key to
understanding the problem.
The first step is to brainstorm all
possible functions of the
product/process/system.
Next, build a FAST Model to help
identify any missing functions.
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Review of FAST Diagramming
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Function Analysis System Technique
Developed in 1964 by Charles W. Bytheway
Applies intuitive logic to test functions
Displays functions in a diagram or model form
Identifies dependence between functions
Creates common language for team
Tests validity of functions
No “correct” FAST model - team consensus
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FAST Failure Modes and
Effects Analysis (FFMEA)
 This approach to problem solving and product/process
improvement uses FAST Modeling as a beginning point to
identify functions to be analyzed using the FMEA approach.
 FMEA & FAST: Describe the product/process and its function.
An understanding of the product or process under
consideration is important to have clearly articulated.
 Create a Block Diagram of the product or process. A block
diagram [FAST Model] of the product/process should be
developed. This diagram shows major components or
process steps [Functions] as blocks connected together by
lines that indicate how the components or steps are related.
From: Failure Modes and Effects Analysis(FMEA), by Kenneth Crow, DRM Associates
http://www.npd-solutions.com/fmea.html
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FAST Example - Overhead
Projector
HOW?
WHY?
F.A.S.T MODEL
OVERHEAD PROJECTOR
FACILITATE
PORTABILITY
OBJECTIVES OR
SPECIFICATIONS
ALLOW
SAFETY
OUTPUT
INPUT
(concept)
W
H
E
N
CONVEY
Information
PROJECT
IMAGE
FOCUS
IMAGE
SUPPORT
IMAGE
AMPLIFY
IMAGE
GENERATE
LIGHT
(concept)
CONVERT
ENERGY
RECEIVE
CURRENT
TRANSMIT
CURRENT
GENERATE
HEAT
DISSIPATE
HEAT
GENERATE
NOISE
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FAST Failure Modes and Effects
Analysis (FFMEA)
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The diagram shows the logical relationships of
components and activities [Functions] and establishes a
structure around which the FMEA can be developed.
Identify Failure Modes. A failure mode is defined as the
manner in which a component, subsystem, system,
process, etc. could potentially fail [or has failed] to meet
the design intent.
A failure mode in one component can serve as the cause
of a failure mode in another component. [This is a basic
premise of FAST]
Failure modes should be listed for function of each
component or process step. At this point the failure
mode should be identified whether or not the failure is
likely to occur.
From: Failure Modes and Effects Analysis(FMEA), by Kenneth Crow, DRM Associates
http://www.npd-solutions.com/fmea.html
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Potential Failure Modes
Corrosion Hydrogen embrittlement
Electrical Short or Open
Torque
Fatigue
Deformation
Cracking
From: Failure Modes and Effects Analysis(FMEA), by Kenneth Crow, DRM Associates
http://www.npd-solutions.com/fmea.html
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Failure Mode Effects
 Describe the effects of those failure modes.
 For each failure mode identified the engineer should
determine what the ultimate effect will be.
 A failure effect is defined as the result of a failure mode
on the function of the product/process as perceived by
the customer.
 They should be described in terms of what the customer
might see or experience should the identified failure
mode occur.
 Keep in mind the internal as well as the external
customer.
From: Failure Modes and Effects Analysis(FMEA), by Kenneth Crow, DRM Associates
http://www.npd-solutions.com/fmea.html
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Possible Effects
 Injury to the user
 Inoperability of the product or process
 Improper appearance of the product or process
 Odors
 Degraded performance Noise
From: Failure Modes and Effects Analysis(FMEA), by Kenneth Crow, DRM Associates
http://www.npd-solutions.com/fmea.html
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FAST Failure Modes and Effects
Analysis (FFMEA)
 Establish a numerical ranking for the severity of the
effect. The intent of the ranking is to help the analyst
determine whether a failure would be a minor nuisance
or a catastrophic occurrence to the customer. This
enables the engineer to prioritize the failures and
address the real big issues first.
 Identify the causes for each failure mode. A failure
cause is defined as a design weakness that may result in
a failure. The potential causes for each failure mode
should be identified and documented. The causes should
be listed in technical terms and not in terms of
symptoms.
From: Failure Modes and Effects Analysis(FMEA), by Kenneth Crow, DRM Associates
http://www.npd-solutions.com/fmea.html
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Possible Causes
Improper torque applied
Improper operating conditions
Contamination
Erroneous algorithms
Improper alignment
Excessive loading
Excessive voltage
From: Failure Modes and Effects Analysis(FMEA), by Kenneth Crow, DRM Associates
http://www.npd-solutions.com/fmea.html
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FAST Failure Modes and Effects
Analysis (FFMEA)
 A numerical weight should be assigned to each cause that
indicates how likely that cause is. A common industry
standard scale uses 1 to represent not likely and 10 to
indicate inevitable.
 Identify controls. Testing, analysis, monitoring, and other
techniques should be identified that can or have been used
on the same or similar products/processes to detect
failures.
 Each of these controls should be assessed to determine
how well it is expected to identify or detect failure modes.
From: Failure Modes and Effects Analysis(FMEA), by Kenneth Crow, DRM Associates
http://www.npd-solutions.com/fmea.html
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FAST Failure Modes and Effects
Analysis (FFMEA)
 After a new product or process has been in use
previously undetected or unidentified failure
modes may appear.
 The FFMEA should then be updated and plans
made to address those failures to eliminate
them from the product/process.
 FFMEA can be used to resolve organizational
and procedural failures as well as product
failure.
From: Failure Modes and Effects Analysis(FMEA), by Kenneth Crow, DRM Associates
http://www.npd-solutions.com/fmea.html
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How FFMEA Improves the VE Methodology
FFMEA is an important methodology that can be
integrated with Six Sigma and VE to generate
superior results.
The point at which FFMEA is most appropriate is
after the function analysis and FAST Model have
been built and functions for improvement have
been chosen.
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The Traditional VE Information
Phase
 Analyze Information
 Define Problem
 Isolate Functions
 Develop FAST Model
 Create Function - Cost Model (or other applicable
Function - Attribute model such as performance, or
risk).
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The Information Phase w/FFMEA
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Analyze Information
Define Problem
Isolate Functions
Develop FAST Model
Create Function - Cost Model (or other applicable
Function - Attribute model such as performance, or risk).
Identify problem functions
Brainstorm potential causes to problem functions
Rate potential causes (1 - 10 scale)
Choose a cut-off (~6) and identify “most likely causes”
to these problems
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Function Analysis Systems Technique
(FAST)
Determine
Defects
HOW
Establish
Container
Integrity
Determine
Condition
WHEN
Determine
Disposition
Identify
Potential
Problems
Determine
Contents
Know
Problem
Contents
OUTPUT
WHY
Inspect
Container
Follow
Inspection
Plan
Examine
(Visually)
Container
Establish
Integrity
Criteria
Verify
Inspection
Plan
Identify
Defects
Define
Container
Integrity
Develop
Inspection
Plan
Verify
Container
ID.
Write
Inspection
Plan
Validate
Inspection
Plan
INPUT
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Identifying Areas for Improvement
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Identify key functions where performance may be
less than adequate (LTA)
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For the functions where performance is LTA,
brainstorm likely causes of failure.

Next, rate these causes on a scale of 1-10 as to
which are the most likely causes of the problem(s).
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Rating Potential Causes
Problems that can
occur with
“Determine
Condition”
Potential Problem
Score
Incorrect Container ID
Incorrect Contents
Inaccurate
Determination
Deterioration After
Inspection/Damage
After Inspection
Inadequate
Procedures
Inadequate Equipment
False Positive Reading
for Excessive Thinning
Inadequate Training
1
5
[Poor] Human Factors
[Interface] - Ability to
see contents, position
container, etc.
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10
9
10
Management Pressure
to Perform
Inadequate Quality
Checks
Inadequate Inspection
Criteria
Subjective Inspection
Criteria
Poor Container
Condition hampers
inspection
Time - Availability - 5
min./drum, 1 min. for
inspection
Poor
Weather/Environment
al Conditions - Human
Factors
6
2
10+
9
7
6
8
7
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Identifying Most Likely Causes of The
Problem(s)
 After rating the likely causes of the problem(s),
choose a cut-off point from which the most likely
causes of failure will be addressed first (usually
about 6 depending on the number of causes).
 For the most likely causes of the problem(s),
brainstorm contributing factors to the causes of
these problem(s).
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Identifying Most Likely Causes of
Failure
MOST LIKELY CAUSES OF
THE PROBLEM

Inadequate Procedures
 Results Not
Tested/Verified
 Writer of Procedure is
not familiar with
process
 Vague Text

Inadequate Training
 Trainers have not had
direct experience with
the inspection
process.
 Inadequate Training
Materials:
 Poor Illustrations
 Field Examples
Poor
 Materials not
definitive enough
MOST LIKELY CAUSES OF
THE PROBLEM (Continued)

Inadequate Inspection
Criteria
 Too vague
 Driven by
Management Goals
 Unclear goals and
objectives available
for development of
criteria.
 Too little quantitative
measures and
performance
parameters.
 Condition could not
be assessed.
 No measurement of
wall thickness...etc.
Figure 3
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FFMEA - Identifying Alternatives
 Next, given the most likely causes and their contributing
factors, you are ready to start identifying potential
alternatives for design, or improvements to the system.
 For each key function that has been identified as not
being performed, or performance is LTA, brainstorm
potential ways to perform, or improve the performance
of these functions.
 The identification of most likely causes of the problems
with those functions focuses the teams attention on the
most needed improvements which facilitates
brainstorming of superior ideas for improvement, or
design of the new system.
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Potential FMEA Form
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Summary
 Value Engineering is a powerful, interdisciplinary
problem solving tool.
 VE is used to improve cost, and performance without
sacrificing quality.
 In fact, VE can be used to improve quality.
 FMEA applied to FAST greatly enhances VE’s ability to
improve quality in existing products, process, or services
 FMEA applied to FAST can also improve new product
development
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