FMEA

Reference Guide

The subject matter contained herein is covered by a copyright owned by Ford Motor Company, Dearborn, MI.
© 2003, Ford Motor Company

The Reference Guide summarizes key course content (i.e., concepts,

charts, equations, definitions). The purpose of the guide is to provide
you with a reference of information you may need on the job. Use the
File/Print command or click on the Printer icon to print a copy.
 Table of Contents

FMEA Overview ........................................................................................... 1

Introduction.................................................................................................................. 1
The Working Model...................................................................................................... 2

Design FMEA (DFMEA) ............................................................................... 3

Introduction.................................................................................................................. 3
DFMEA Step 1............................................................................................................. 4
DFMEA Step 2............................................................................................................. 6
DFMEA Step 3............................................................................................................. 7
Robustness Linkages .................................................................................................. 8

Process FMEA (PFMEA)............................................................................ 10

Introduction................................................................................................................ 10
PFMEA Step 1 ........................................................................................................... 11
PFMEA Step 2 ........................................................................................................... 14
PFMEA Step 3 ........................................................................................................... 14

Concept FMEA (CFMEA) ........................................................................... 18

Introduction................................................................................................................ 18
CFMEA Step 1........................................................................................................... 18
CFMEA Step 2........................................................................................................... 18
CFMEA Step 3........................................................................................................... 19

FMEA Linkage Diagram ............................................................................. 19

 FMEA Overview
Introduction

Define FMEA FMEA (Failure Mode and Effects Analysis) is a structured group of activities, which:

• Identify and organize potential Failure Modes and their Effects

• Identify and prioritize actions
• Document the process

FMEAs (Design, Process, etc.) are primarily concerned with problem prevention, aimed at
reducing customer dissatisfaction for all customers - consumer, service, etc.

For additional information regarding FMEA processes, tools and software, visit
http://www.quality.ford.com/cpar/fmea/.

Purpose of By implementing FMEAs properly, failures, design/process changes, and workloads are more
FMEA evenly distributed and occur prior to Job #1.

Furthermore, the purpose of completing an FMEA is to:

• Improve the quality, reliability, and safety of the evaluated products
• Reduce product redevelopment timing and cost
• Document and track actions taken to reduce risk
• Identify Critical Characteristics and Significant Characteristics
• Act as a "lessons learned" input to System Design Specifications (SDS), Design Verification
Plans (DVP), control plans, design guides, and other documents and procedures
• Improve customer satisfaction
• Improve Ford product quality

When to There are three basic cases for which FMEAs are generated or updated, each with a different
Generate an scope or focus:
FMEA
• Case 1: New designs (component or system), new technology, or new process. The scope of
the FMEA is the complete design, technology, or process.

• Case 2: Modification to existing design (component or system) or process (assumes there is a

FMEA for the existing design or process). The scope of the FMEA should focus on the
modification to design or process, possible interactions due to the modification, and field
history.

• Case 3: Use of existing design (component or system) or process in a new environment,

location, or application (assumes there is an FMEA for the existing design or process). The
scope of the FMEA is the impact of the new environment or location on the existing design or
process.

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The Working Model

Introduction The FMEA Working Model helps team members perform FMEAs. The Working Model
is consistent with the SAE Standard J1739. It is a "flow diagram" of the FMEA thought
process overlaid on an FMEA form.
Although there are minor differences in the forms for the different types of FMEAs, the
thinking process is the same for all types of FMEAs.
The key steps of the Working Model are grouped into three Steps. These Steps are briefly
addressed on the following page and will be discussed in depth as each type of FMEA is
discussed. Using the Working Model is mandatory. However, before using the Working
Model you must:

1. Identify the core team

2. Define the scope of the FMEA, which involves identifying:
a. Boundaries - using boundary diagrams
b. Interfaces - using Interface Matrix and P-diagram
3. Identify the support team

FMEA Working Model

Step 1

Step 2

Step 3

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The Working Model, continued

Working Step 1 consists of the following steps:

Model Step 1
1. Define Function of the part or process being analyzed.
2. Identify the Failure Modes of the Function.
3. Identify the Effects of the Failure Modes.
4. Assess the Severity (S) of the Effect on a scale of 1 to 10.
5. If possible, recommend actions to eliminate the Failure Mode.

Working If the Failure Mode cannot be eliminated, then continue with Step 2, which consists of the
Model Step 2 following steps:

1. Identify all of the Causes of the Failure Mode.

2. Assess how often the Causes occur on a scale of 1 to 10.
3. Recommend actions to eliminate the Cause.

Working If the Causes cannot be eliminated, then continue with Step 3, which consists of the
Model Step 3 following steps:

1. Identify Prevention controls to reduce occurrence.

2. Identify Detection controls (e.g., tests, inspection) to address Failure Modes and Causes.
3. Assess the effectiveness of the Detection controls on a scale of 1 to 10.
4. Recommend the appropriate Detection controls.

Design FMEA (DFMEA)

Introduction

DFMEA The DFMEA supports the design process by reducing the risk of failure by:
Objective
1. Identifying all potential Failure Modes and their Severity
2. Identifying and resolving all Causes by design actions
3. Testing the design to make sure all Failure Modes/Causes are eliminated or their
Occurrence (O) is significantly reduced, prior to release

Team The DFMEA Core Team consists of the design engineer (lead) and the related
manufacturing/process engineer. The Core Team then identifies others to be members of
the Support Team (e.g., customer service, suppliers, global test operations, and corporate
quality).

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DFMEA Introduction, continued

Scope and The Scope of the DFMEA is the boundary or extent of the analysis and defines what is
Boundary included and excluded.
Diagram
1. Consider a system, sub-system, or component that can be represented as a "block".
2. Represent other components in the high-level assembly, including all system attachments
and mechanisms.
3. Identify relationships with:
a. Other systems
b. Manufacturing/assembly tools
c. Service/customer adjustment
4. Construct a boundary diagram using the "block".
5. Identify the scope by drawing a dotted line around those "blocks" that are to be included.
"Blocks" outside the dotted line are excluded from the analysis of the FMEA.

FPDS Timing DFMEA starts at Strategic Intent <SI> and complete "First Pass" by Program Approval <PA>.

DFMEA Step 1
Define The first step in DFMEA is to define Function, which must be written in a measurable/verifiable
Function format. A description of Function should answer the question: "What is this item supposed to
do?" Function is the design intent or engineering requirement of the item being analyzed.

Identify Failure For each identified Function, you must identify what can go wrong. Failure Modes fall
Modes of the within these four categories:
Function
• No Function—not operational
• Partial/Over/Degraded Function—not all of the function is operating
• Intermittent Function—occasionally does not function
• Unintended Function—unexpected function occurs due to system interaction

Note: Failure Modes must be directly related to the Function.

Identify the Having documented the Failure Modes, we must now consider the Effects of each Failure Mode.
Effects of the The use of the DFMEA Effects List is highly recommended to evaluate the effects on the part,
Failure Modes the high-level assembly, the system, the vehicle, the customer, and governmental regulations.

Assess the Once the effects have been documented in the Effects Column of the FMEA form, they need
Severity of the to be evaluated for Severity. Severity is linked to the effect of failure, and each effect
Effect on a identified in the list must be assigned a Severity rating. These should be noted in parentheses
scale of 1 to 10 following each Effect. Severity is a relative ranking, within the scope of the individual
FMEA. Each effect must be assigned a Severity rating using the Severity Rating Table.

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DFMEA Step 1, continued

DFMEA Severity Rating Table

Effects Criteria: Severity of Effect Ranking
Hazardous — Very high Severity ranking when a potential Failure Mode 10
without warning affects safe vehicle operation and/or involves noncompliance
with government regulation without warning.
Hazardous— Very high Severity ranking when a potential Failure Mode 9
with Warning affects safe vehicle operation and/or involves noncompliance
with government regulation with warning.
Very High Vehicle/item inoperable (loss of primary function). 8
High Vehicle/item operable but at a reduced level of performance. 7
Customer very dissatisfied.
Moderate Vehicle/item operable but comfort/convenience item(s) 6
inoperable. Customer dissatisfied.
Low Vehicle/item operable but comfort/convenience item(s) 5
operable at a reduced level of performance. Customer
somewhat dissatisfied.
Very Low Fit and finish/squeak and rattle item does not conform. Defect 4
noticed by most customers (greater than 75%).
Minor Fit and finish/squeak and rattle item does not conform. Defect 3
noticed by 50% of customers.
Very Minor Fit and finish/squeak and rattle item does not conform. Defect 2
noticed by discriminating customers (less than 25%).
None No discernible effect. 1

Selection of The highest Severity identified in the Effects column is entered in the Severity Column.
Severity and
Classification For Severity values of 9 or 10, where safety and/or government regulations are affected:

• Enter YC in the Classification column

• If possible, eliminate the Failure Mode without analyzing Cause
• Assure that information is communicated to the PFMEA team after Causes have been
generated

Note: For a particular Failure Mode, there is only one Severity rating in the Severity column of
the FMEA form.

Recommend The FMEA team tries to eliminate the Failure Mode. If it is not possible, continue to Step 2, Cause
Actions of Failure Mode.

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DFMEA Step 2

Address Cause This Step addresses the Cause (or design weakness), which results in the Failure Mode.

Identify all of Potential Cause of failure is defined as an indication of a design weakness, the consequence of
the Causes of which is the Failure Mode. Hence, Causes should be written as a design weakness, which
the Failure should be corrected.
Mode
When brainstorming potential Causes of each failure, begin with the following assumptions:

• Assumption 1: The item is manufactured and assembled within engineering specifications.

• Assumption 2: The design may include a deficiency that may cause unacceptable
variation, (e.g., misbuilds or errors in the manufacturing and assembly process.)

Use Fishbone Diagram or Why Ladder to identify all the Causes, and remember that Root
Causes:

• Are the basic or underlying Causes for a failure

• Must be determined for all Failure Modes with a Severity of 9 or 10
• Are described in terms of part characteristics, such as dimension, size, form, location,
orientation, texture, hardness, tensile strength, appearance, coating, reflectivity, etc.

Note: The Root Cause is the reason for the primary non-conformance and is the item that
requires change to achieve permanent preventive/corrective action.

Assess how After all the Causes of the Failure Modes have been identified, determine how often each
often the Cause occurs on a scale of 1 to 10. Occurrence can be defined as the likelihood that a
Causes occur specific Cause will occur during the design life (e.g., 150,000 miles or 10 years). Refer to
the following Occurrence Rating Table that is used to estimate the failure rate and/or
criteria to develop a rating for each Cause.

DFMEA/PFMEA Occurrence Rating Table

Probability of Failure Likely Failure Rates Over Design Life Ranking
> 100 per thousand vehicles/items 10
Very High: Persistent failures
50 per thousand vehicles/items 9
20 per thousand vehicles/items 8
High: Frequent failures
10 per thousand vehicles/items 7
5 per thousand vehicles/items 6
Moderate: Occasional failures 2 per thousand vehicles/items 5
1 per thousand vehicles/items 4
0.5 per thousand vehicles/items 3
Low: Relatively few failures
0.1 per thousand vehicles/items 2
Remote: Failure is unlikely < 0.01 per thousand vehicles/items 1

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DFMEA Step 2, continued

Classification When a Failure Mode/Cause combination has a Severity rating of 5 to 8 and an Occurrence rating
of 4 or higher, a potential Significant Characteristic exists. In the classification column, enter the
letters "YS" when a potential Significant Characteristic is identified. At this time, the PFMEA
team should start considering special plant inspections to catch "YS" related errors.

Actions to Address all Causes by recommending design actions, which will either eliminate the Cause or
eliminate the lower its occurrence. If no action is taken, explain why. Remember that Causes address Failure
Cause Modes, not Effects.

DFMEA Step 3
Current Design There are two types of Design Controls/features to consider:
Controls
• Prevention: Prevent the Cause/Mechanism or Failure Mode/Effect from occurring, or reduce
the rate of Occurrence. These are design actions.
• Detection: Detect the Cause/Mechanism or the Failure Mode, either by analytical or physical
methods, before the item is released to production. These are tests.

Detection Detection rating is the team's assessment of the test being conducted to identify Cause and/or Failure
Mode. Detection is a relative ranking within the scope of the individual FMEA. In order to achieve a
lower ranking, generally the planned design control (e.g., validation, and/or verification activities)
has to be improved. Detection ratings are given in the following table.

Note: When several detection controls (or tests) are listed for a Cause, use the best (or lowest) rating.

DFMEA Detection Rating Table

Detection Criteria: Likelihood of Detection by Design Control Ranking
Design control will not and/or cannot detect a potential Cause/Mechanism and
Absolute Uncertainty 10
subsequent Failure Mode; or there is no design control.
Very remote chance the Design Control will detect a potential Cause/Mechanism
Very Remote 9
and subsequent Failure Mode.
Remote chance the Design Control will detect a potential Cause/Mechanism and
Remote 8
subsequent Failure Mode.
Very low chance the Design Control will detect a potential Cause/Mechanism and
Very Low 7
subsequent Failure Mode.
Low chance the Design Control will detect a potential Cause/Mechanism and
Low 6
subsequent Failure Mode.
Moderate chance the Design Control will detect a potential Cause/Mechanism and
Moderate 5
subsequent Failure Mode.
Moderately High chance the Design Control will detect a potential
Moderately High 4
Cause/Mechanism and subsequent Failure Mode.
High chance the Design Control will detect a potential Cause/Mechanism and
High 3
subsequent Failure Mode.
Very high chance the Design Control will detect a potential Cause/Mechanism and
Very High 2
subsequent Failure Mode.
Design Control will almost certainly detect a potential Cause/Mechanism and
Almost Certain 1
subsequent Failure Mode.

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DFMEA Step 3, continued

Risk Priority Compute the Risk Priority Number (RPN) which equals Severity times Occurrence times
Number (RPN) Detection (S x O x D), for each Cause and enter in the RPN column.

Note: There will be one RPN for each Cause.

Recommended The purpose of recommending actions in a DFMEA is to eliminate potential Failure Modes or
Actions reduce their occurrence. The team should prioritize actions based on those Failure Modes with:

• Effects that have the highest Severity ratings

• Causes that have the highest Severity times Occurrence (S x O) or Criticality ratings
• The Highest RPN (S x O x D) ratings

Note: Threshold values for RPN should not be used.

Robustness Linkages

Introduction Robustness Linkages have been added to the FMEA process to significantly reduce vehicle
campaigns, enhance the corporate image, reduce warranty claims, and increase customer
satisfaction. These Robustness Linkages primarily emanate from the P-diagram, which identifies
the five Noise Factors. These factors need to be addressed early to make the design insensitive to
the noise factors. This is the essence of Robustness. It is the engineer's responsibility to ensure
that the Robustness Linkages are captured in the engineering documentation.

P-Diagram

Noise Factors
1. Piece-to-Piece Variation
2. Changes Over Time/Mileage
3. Customer Usage & Duty Cycles
4. Environmental
5. System Interactions

Response
Signal Factor System (Ideal
Function)

Control Factors Error

(Design Parameters, which can be changed States
to improve robustness)

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Robustness Linkages, continued

Interface The interface matrix is a recommended Robustness tool that acts as an input to a DFMEA.
Matrix The interface matrix identifies and quantifies the strength of system interaction by:

• Showing whether the relationship is necessary or adverse

• Identifying the type of relationship

The interface matrix is an input to the Potential Causes/Mechanisms Failure column of the
DFMEA and also to the P-diagram.

Headlamp Housing
Grill Opening Panel

Hood

Screws/Fasteners
Headlamp

Wiring/Electrical System

Connector

Body
-1 -2 -1 -1 2 -2
Grill Opening Panel

Hood -1 -2 -1 -1 12

Headlamp Housing -1 -1 -1 -1 2

Headlamp 2 -2 -1 -1 2

Screws/Fasteners
Wiring/Electrical System

Connector

Body

P E P: Physically touching
I M I: Information Exchange
E: Energy Transfer
M: Material Exchange

Numbers in each corner represent the above interface types, with values denoting the
following:

+2 Interaction is necessary for function

+1 Interaction is beneficial, but not absolutely necessary for functionality
0 Interaction does not affect functionality
-1 Interaction causes negative effects but does not prevent functionality
-2 Interaction must be prevented to achieve functionality

(Negative values are analyzed for recommended action.)

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Robustness Linkages, continued

Robustness The diagram below shows how the FMEA process has a robustness focus. The Robustness
Linkage tools are inputs into the DFMEA process:
Diagram

Boundary Qualifies and clarifies the relationships

Diagram between Systems.

Interface Identifies and qualifies the strength of

Matrix System Interactions

Identifies Noise and Control

P-Diagram
Factors and Error States

FMEA with
Robustness
Linkages

Summarizes Error States and links 5 Noise Robustness &

Factors to the Design Verification Plans Reliability
Checklist
Design
Verification
Plan

Note: Boundary Diagram, Interface Matrix, and P-Diagram should be completed before starting
the FMEA process. The Robustness and Reliability checklist is the output of the FMEA.

Process FMEA (PFMEA)

Introduction

PFMEA PFMEA:
Objective
• Is a technique employed to analyze the manufacturing and assembly processes
• Focuses on eliminating potential Failure Modes of the manufacturing and assembly processes

PFMEA consists of three Steps similar to DFMEA except that now the focus is on process
function/purpose as opposed to component function.

Team The PFMEA Core Team includes representatives from manufacturing/process engineering and the
appropriate design engineer. The Core Team identifies others to be members of the Support Team
(e.g., technical specialists, suppliers, maintenance, production, and next process engineer).

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PFMEA continued

Scope/Process The scope for a PFMEA is determined by:

Flow Chart
• Creating a macro (process) flow diagram
• Identifying the boundary
• Creating a micro (process) flow diagram

Without properly determining the scope, the FMEA may either go too far or not far enough. The
process flow must be created for the PFMEA.

Characteristic A part characteristic is a feature about the part, which when compromised, generates a Failure
Matrix Mode. It may be a dimension, such as a hole’s inside diameter, or it may be a specification such as
material composition. Once all the Failure Mode’s associated part characteristics are identified,
they must be summarized and communicated to the corresponding PFMEA team. These
characteristics are then placed on a Characteristic Matrix, aligning them individually with each of
the process steps where they can potentially be compromised. It is important to understand that
anytime one of these part characteristics is compromised, the associated DFMEA Failure Mode is
reintroduced along with its effects. Therefore, the part characteristic is the link between the
DFMEA and PFMEA.

FPDS Timing PFMEA should start at Strategic Conformation <SC>, and complete First Pass by Product
Readiness <PR>.

PFMEA Step 1

Process The function/purpose of a process operation is what is achieved at that operation. It should:
Function/
Requirement • Describe what the operation is there to do
• Be precisely expressed in a measurable format

Identify For each identified process purpose, the PFMEA team must identify what can go
Potential wrong. Potential Failure Mode is defined as the manner in which the process could
Failure Mode potentially fail to meet the process requirements and/or design intent as described in the
Process Function/Requirements column. Like DFMEA, Failure Modes fall within four
groupings that are useful as thought starters:

• No Function—not operational
• Partial/Over/Degraded Function—not all of the function is operating
• Intermittent Function—occasionally does not function
• Unintended Function—unexpected function occurs due to system interaction

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PFMEA Step 1, continued

Effects of Once the team has identified and listed the potential Failure Modes, it should next consider the
Failure Mode effects of each Failure Mode.

Potential Effects of Failure are defined as the effects of the Failure Mode on the customer(s). The
customer(s) in this context could be the next operation, subsequent operations or locations, the
dealer, and/or the vehicle owner. Use the PFMEA Effects List to identify all effects.

Severity Once the Effects have been documented, they need to be evaluated for Severity (refer to the
Severity Table on the next page). Severity is linked to the Effect of failure, and each effect
identified in the list must be assigned a Severity rating. These should be noted in parentheses
following each Effect. Failure in a process can affect the product (customer) and/or the process
(manufacturing/assembly). The team must analyze the nature of the Effect using the PFMEA
Severity Table.

Selection of The highest Severity identified in the Effects column is entered in the Severity column.
Severity and
Classification • For product related Severity of 9 or 10, enter ∇ (Critcal Characteritics or Inverted Delta) in
the classification column.
• For process related Severity of 9 or 10, enter OS (Operator Safety) in classification column.

Note: For a particular Failure Mode, there is only one Severity rating in the Classification column
of the FMEA form.

Recommended Recommending actions to eliminate the Failure Mode completes Step 1 of the Working Model.
Actions If the Failure Mode cannot be eliminated, continue with the analysis in Step 2.

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PFMEA Step 1, continued

PFMEA Severity Rating Table

Effect Criteria: Severity of Effect Ranking
This ranking results when a potential Failure Mode results in a final customer and/or
a manufacturing/assembly plant defect. The final customer should always be
considered first. If both occur, use the higher of the two severities.
Customer Effect Manufacturing/Assembly Effect
Hazardous Very high Severity ranking when a potential Or may endanger operator (machine or 10
without warning Failure Mode affects safe vehicle operation and/or assembly) without warning.
involves noncompliance with government
regulation without warning.
Hazardous with Very high Severity ranking when a potential Or may endanger operator (machine or 9
warning Failure Mode affects safe vehicle operation and/or assembly) without warning.
involves noncompliance with government
regulation with warning
Very High Vehicle/item inoperable (loss of primary function) Or 100% of product may have to be scrapped, 8
or vehicle/item repaired in repair department
with a repair time greater than one hour.
High Vehicle/item operable but at a reduced level of Or product may have to be sorted and a 7
performance. Customer very dissatisfied. portion (less than 100%) scrapped, or
vehicle/item repaired in repair department
with a repair time between half an hour and
an hour.
Moderate Vehicle/item operable but Comfort/Convenience Or a portion (less than 100%) of the product 6
item(s) inoperable. Customer dissatisfied. may have to be scrapped with no sorting, or
vehicle/item repaired in repair department
with a repair time less than half an hour.
Low Vehicle/item operable but Comfort/Convenience Or 100% of product may have to be reworked, 5
item(s) operable at a reduced level of performance. or vehicle/item repaired off-line but does not
Customer somewhat dissatisfied go to repair department.
Very Low Fit and finish/Squeak and rattle item does not Or the product may have to be sorted, with no 4
conform. Defect noticed by most customers scrap, and a portion (less than 100%)
(greater than 75%) reworked.
Minor Fit and finish/Squeak and rattle item does not Or a portion (less than 100%) of the product 3
conform. Defect noticed by 50 percent of may have to be reworked, with no scrap,
customers. online but out-of-station.
Very Minor Fit and finish/Squeak and rattle item does not Or a portion (less than 100%) of the product 2
conform. Defect noticed by discriminating may have to be reworked, with no scrap,
customers (less than 25 percent). online but in-station.
None No discernible effect. Or slight inconvenience to operation or 1
operator, or no effect.

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PFMEA Step 2

Introduction PFMEA Step 2 begins with the same Failure Mode. The Causes are a process and/or
design weakness, which results in the Failure Mode.

Identifying Potential Cause of failure is described in terms of something that can be corrected or
Causes controlled. When brainstorming potential Causes, there are two assumptions to begin with.
These two assumptions are not mutually exclusive, but each must be considered sequentially.

• Assumption 1: Incoming parts/materials to the operation are correct.

• Assumption 2: Consider that there are incoming sources of variation.
Like DFMEA, use a Fishbone diagram or Why Ladders to identify all Causes. The Root Cause
must be determined when the Severity is 9 or 10.

Rating the Occurrence is the likelihood that a Specific Cause/Mechanism will occur. Occurrence Ratings
Occurrence for in PFMEA are the same as they are in DFMEA. Refer to the DFMEA/PFMEA Occurrence
each Cause Table on page 8.

Classification Once Occurrence has been determined for each Cause, the need for a Special
Characteristic has to be established. For customer/product related Severity of 5 to 8 and
Occurrence of 4 to 10, enter SC (Significant Characteristic) in the Classification column.
For manufacturing/process related Severity of 5 to 8 and Occurrence of 4 to 10, enter HI
(High Impact) in the Classification column.
Note: Criticality is defined as the product of Severity x Occurrence (S x O).

Recommended All Causes identified in the PFMEA should be addressed. All ∇ and SC related Causes
Actions must have Special Controls (inspections) in the Plant to assure no defective parts leave the
plant. If the Failure Mode and their Causes cannot be eliminated, proceed to Step 3.

PFMEA Step 3
Current There are two types of process controls/features to consider:
Process
• Type 1: Prevention: Prevent the Cause/Mechanism or Failure Mode from occurring,
Controls
or reduce their rate of Occurrence – could be a design and/or process actions.
• Type 2: Detection: Detect the Cause/Mechanism and lead to corrective actions –
generally this is an inspection conducted in the plant.

How to Identify The preferred approach is to first use Type 1 controls if possible. The initial Occurrence
Process rankings will be affected by the Type 1 controls provided they are integrated as part of the
Controls process intent. The initial Detection rankings will be based on the Type 2 current process
controls, planned for production operation. The Occurrence ranking may need to be
revised after the identification of Type 1 prevention controls.

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PFMEA Step 3, continued

Detection Detection rating is the team's assessment of the inspection being conducted in the plant to
identify Cause and/or Failure Mode. If several detections (or inspections) controls are listed
for a particular Cause, use the best (or lowest) rating. Manual/visual inspection has poor
ratings (6-10). Detections for ∇ and SC are called Special Controls and should be excellent
(non manual) inspections with low ratings. The objective of Special Controls is to ensure
that no defective parts leave the plant. Refer to the following table for detection ratings.

PFMEA Detection Rating Table

Inspection Types
Detection Criteria A B C Suggested Range of Ranking
Detection Methods
Almost Absolute certainty of non- Cannot detect or is not checked. 10
Impossible Detection.
Very Remote Controls will probably not detect. Control is achieved with indirect 9
or random checks only.
Remote Controls have poor chance of Control is achieved with visual 8
Detection. inspection only.
Very Low Controls have poor chance of Control is achieved with double 7
Detection. visual inspection only.
Low Controls may detect. Control is achieved with charting 6
methods, such as SPC (Statistical
Process Control).
Moderate Controls may detect. Control is based on variable 5
gauging after parts have left the
station, OR Go/No Go gauging
performed on 100% of the parts
after parts have let the station.
Moderately Controls have a good chance to Error Detection in subsequent 4
High detect. operations, OR gauging
performed on setup and first-piece
check (for set-up Causes only).
High Controls have a good chance to Error Detection in-station, OR 3
detect. error Detection in subsequent
operations by multiple layers of
acceptance; supply, select, install,
verify. Cannot accept discrepant
part.
Very High Controls almost certain to detect. Error Detection in-station 2
(automatic gauging with
automatic stop feature). Cannot
pass discrepant part.
Certain Controls certain to detect. Discrepant parts cannot be made 1
because item has been error
proofed by process/product
design.
Inspection Types:
A. Error Proofed
B. Gauging
C. Manual Inspection
Note: Shaded areas indicate the inspection type(s) used for a given rank.

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PFMEA Step 3, continued

Risk Priority Compute the Risk Priority Number (RPN) that equals Severity times Occurrence times
Number (RPN) Detection (S x O x D), for each Cause and enter in the RPN column.

Recommended The purpose of recommend actions in a PFMEA is to eliminate potential Failure Modes or
Actions reduce their occurrence. The team should prioritize actions based on those Failure Modes with:

• Effects that have the highest Severity ratings

• Causes that have the highest Severity times Occurrence (S x O) or Criticality ratings
• The Highest RPN (S x O x D) ratings

Note: Threshold values for RPN should not be used.

Special All products and processes have features described by characteristics that are important
Characteristics and need to be controlled. However, some characteristics, called Special Characteristics,
required extra effort to minimize failure. Refer to the table on the following page.

1. Critical Characteristics (∇): Critical characteristics are product requirements that

affect compliance with government regulation or safe vehicle/product function
(Severity of 9 to 10), which require Special Controls that must be listed on a Control
Plan.

2. Significant Characteristics (SC): Significant Characteristics are those product

requirements that are important for customer satisfaction (Severity of 5 to 8 and
Occurrence of 4 to 10). They also require Special Controls, which are summarized on
a Control Plan.

3. Operator Safety Characteristics (OS): Operator safety characteristics are related to

a process parameter that does not affect the product but may have an impact on the
safety or governmental regulations applicable for the process operation, (e.g.,
Occupational Safety and Health Administration (OSHA) requirements). These are
Failure Modes with a Severity rating of 9 or 10 and only effects the process.

4. High-Impact Characteristics (HI) are related to a process parameter that does not
affect the product but may have an impact on the operation of the process itself or
subsequent operations. These are Failure Modes with a Severity rating of 5 to 8 and
Occurrence of 4 to 10. HI does not require special control.

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PFMEA Step 3, continued

DFMEA/PFMEA Special Characteristic Table

Actions
FMEA Type Classification To Indicate Criteria Required
Design YC A potential Critical Severity = 9, 10 Highlight for
Characteristic (Initiate PFMEA Team
Customer/Product Effect

PFMEA) Focus
Design YS A potential Significant Severity = 5 - 8 and Highlight for
Characteristic (Initiate Occurrence = 4 - 10 PFMEA Team
PFMEA) Focus
Design Blank Not a potential Critical Severity < 5 Not Required
Characteristic or
Significant Characteristic
Process ∇ A Critical Characteristic Severity = 9, 10 Special Control
Required*
Process SC A Significant Severity = 5 - 8 and Special Control
Characteristic Occurrence = 4 - 10 Required*
Process HI High Impact Severity = 5 - 8 and Emphasis
Assembly Effect
Manufacturing/

Occurrence = 4 - 10
Process OS Operator Safety Severity = 9, 10 Safety Sign-Off

Process Blank Not a Special Other Does Not Apply

Characteristic

* Included in the Control Plan

Special Special Controls are those manufacturing and assembly process methods, administrative
Controls actions, techniques, and tests beyond the normal and customary controls used to prevent
and/or contain product defects prior to release for manufacturing or assembly.

Special Controls are:

• Interim controls directed by manufacturing

• Aimed at detecting and containing a Special Characteristic–related (∇ and SC) defect
prior to shipment
• Documented in the Control Plan

Control Plans A Control Plan is a written description of the system for controlling production processes.
It describes a producer's quality planning actions for a specific product or process. Control
Plans contain all applicable Critical and Significant Characteristics.

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 Concept FMEA (CFMEA)
Introduction

CFMEA CFMEA is similar to the Design and Process FMEAs, including Robustness Linkages.
Overview CFMEA is used to analyze concepts at early (or pre-hardware) stages and is typically
performed for systems and sub-systems, but it can also be performed on components.
CFMEAs are critical to the advanced technology process and are an integral part of the
Implementation Readiness process that must be completed by the Strategic Intent <SI>
gateway.

CFMEA Step 1

CFMEA Once the team is established and the CFMEA scope is set, it is time to move on to Step 1.
Objectives Step 1 for CFMEA is fundamentally the same as both the DFMEA and PFMEA.

In CFMEA, Failure Modes, Effects and Severity are determined the same as in DFMEA
and PFMEA. For recommended actions, CFMEA provides more opportunity to take
actions in Step 1, because it is so early in the development cycle. In Step 1, changes:

• Are typically major design or process changes

• Tend to improve robustness
• Lead to recommended actions that include updates to design guidelines, SDS,
WCR, machinery specifications, maintenance schedules, process flows, etc.

CFMEA Step 2

Determine After Step 1, if Failure Modes have not been eliminated, then complete Step 2, which is
Causes and similar to Step 2 of DFMEA and PFMEA.
Rank
Occurrences • CFMEA Causes are determined in a manner similar to DFMEA and PFMEA, except
that the Cause refers to a deficiency in the concept, rather than in the hardware.
• Ranking occurrences is done the same as in DFMEA and PFMEA, except that
occurrence in a CFMEA requires creative team analysis, as historical data are limited
or non-existent.
• CFMEA teams may take actions at Step 2. There is the possibility of no Occurrence
number, which leads to a rating of 10, so the action is to get some data.

Analyzing the interfaces and interactions is especially important. A major benefit of the
Concept FMEA is the identifying of potential Failure Modes caused by interactions that
must be addressed before the concept can be approved and implemented.

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CFMEA Step 3

Controls As in DFMEA and PFMEA, Step 3 is completed for all Failure Modes that still exist after
completing Steps 1 and 2. Step 3 of the CFMEA will look fairly familiar, but the controls
are quite different in a CFMEA.

Since CFMEA is done prior to hardware solutions, typical controls, may include:

• Computer simulation
• Mathematical modeling
• Load calculations
• Environmental testing
• Laboratory testing

FPDS Timing CFMEA's are started at Kick-Off <KO> and should be completed prior to Strategic Intent <SI>.

FMEA Linkage Diagram

Introduction The inputs and outputs for each type of FMEA and how they are interrelated are shown in
the following diagram. FMEA is an important part of Ford product development and
manufacturing, and serves as an important link between many elements of the system.

Remember there are many other information sources available that are valuable resources
for FMEAs. Consult the FMEA Handbook for further information regarding FMEA's.
For assistance in completing an FMEA, use the FMEA Checklist.

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 FMEA Linkage Diagram

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