FMEA Handbook

Front Cover

POTENTIAL FAILURE MODE AND EFFECTS ANALYSIS (FMEA) REFERENCE MANUAL

The content of this document is the technical equivalent of SAE J-1739. Potential Failure Mode and Effects Analysis (FMEA) should be used by suppliers to companies subscribing to QS-9000 or equivalent document.

First Edition Issued February, 1993 • Second Edition, February, 1995 • Third Edition, April, 2001 Copyright © 1993, © 1995, © 2001 DaimlerChrysler Corporation, Ford Motor Company, General Motors Corporation

FOREWORD 1st and 2nd Edition This reference Manual and Reporting Format was developed by the Failure Mode and Effects Analysis (FMEA) teams at Chrysler, Ford and General Motors, working under the auspices of the Automotive Division of the American Society for Quality Control (ASQC) and the Automotive Industry Action Group (AIAG). The ASQC/AIAG Task Force charter is to standardize the reference manuals, procedures, reporting formats and technical nomenclature used by Chrysler, Ford, and General Motors in their respective supplier quality systems. Accordingly, this manual and format, which is approved and endorsed by Chrysler, Ford and General Motors, should be used by suppliers implementing FMEA techniques into their design/ manufacturing processes. In the past, Chrysler, Ford and General Motors each had their own guidelines and formats for insuring supplier FMEA compliance. Differences between these guidelines and formats resulted in additional demands on supplier resources. To improve upon this situation, Chrysler, Ford and General Motors agreed to develop, and, through AIAG, distribute this Manual. The work group responsible for the Manual was led be George Baumgartner of Ford Motor Company. This Manual provides general guidelines for preparing an FMEA. It does not give specific instructions on how to arrive at each FMEA entry, a task best left to each FMEA team. This Manual also is not intended to be a comprehensive FMEA reference source or training document. While these guidelines are intended to cover all situation normally occurring either in the design phase or process analysis, there will be questions that arise. These questions should be directed to your customer's Supplier Quality Assurance (SQA) activity. If you are uncertain as to how to contact the appropriate SQA activity, the buyer in your customer's Purchasing office can help. The Task Force gratefully acknowledges: the leadership and commitment of Vice Presidents Thomas T. Stallkamp at Chrysler, Norman F. Ehlers at Ford, and J. Ignasio Lopez de Arriortua of General Motors; the assistance of the AIAG in the development, production, and distribution of the Procedure; the guidance of Task Force principals Russ Jacobs (Chrysler), Steve Walsh (Ford), Dan Reid (General Motors), and Rad Smith; and the assistance of the ASQC Automotive Division Reading Team. This team, led by Tripp Martin (Peterson Spring), reviewed the Manual for technical content and accuracy and made valuable contributions to form and content. Since the Manual was developed to meet specific needs of the automotive industry, the ASQC voluntary standards process defined by ASQC policies and procedures was not used in its development.

Additional copies can be ordered from AIAG and/or permission to copy portions of this Procedure for use within supplier organizations should be obtained from AIAG at 248-358-3003.

FOREWORD 3rd Edition The FMEA 3rd Edition (QS-9000) is a reference manual to be used by suppliers to DaimlerChrysler, Ford Motor Company, and General Motors Corporation as a guide to assist them in the development of both Design and Process FMEAs. This reference manual is intended to clarify questions concerning the technical development of FMEAs. This reference manual is consistent with the Supplier Quality Requirements Task Force charter to standardize the reference manuals, procedures, reporting formats and technical nomenclature used by suppliers to DaimlerChrysler, Ford Motor Company, and General Motors Corporation. Accordingly the FMEA, 3rd Edition Manual is written to provide guidance for the supplier. The manual does not define requirements, it does provide general guidelines intended to cover situations normally occurring when preparing FMEAs during the design phase or process analysis phase. This manual is the technical equivalent of SAE J1739, for Design and Process FMEAs. However, it does not include an application for Machinery FMEA. Interested parties in Machinery FMEA may refer to SAE J1739 for a related example. The Supplier Quality Requirements Task Force would like to thank the following individuals, and their companies, who have contributed their time and efforts to the development of either this edition of the FMEA manual or earlier editions. 3rd Edition Kevin A. Lange - DaimlerChrysler Steven C. Leggett - General Motors Corporation Beth Baker - AIAG Earlier Editions Howard Riley - DaimlerChrysler George R. Baumgartner - Ford Motor Company Lawrence R. McCullen - General Motors Robert A. May - Goodyear Tripp Martin - Peterson Spring

Mark T. Wrobbel - DaimlerChrysler Rebecca French - General Motors Mary Ann Raymond - Bosch William Ireland - Kelsey-Hayes

In addition, the Supplier Quality Requirements Task Force would like to thank the following individuals from the SAE J1739 work group who contributed significantly to the technical changes and improvements in this edition. William D. Carlson - DaimlerChrysler Glen R. Vallance - Ford Motor Company Carl S. Carlson - General Motors Corporation This manual is a copyright of DaimlerChrysler, Ford Motor Company and General Motors Corporation, with all rights reserved. Additional copies may be obtained from AIAG, Southfield, Michigan, by calling 248-3583003. Supply chain organizations of DaimlerChrysler, Ford Motor Company or General Motors Corporation have permission to copy forms used in this manual.

TABLE OF CONTENTS Page Number General Information ................................................................................................................................... 1 Overview ......................................................................................................................................... What Is an FMEA ............................................................................................................................ Manual Format ................................................................................................................................ FMEA Implementation ....................................................................................................................

1 1 1 2

Design FMEA .............................................................................................................................................. 7 Introduction ................................................................................................................................................... 9 Customer Defined ........................................................................................................................... 9 Team Effort ..................................................................................................................................... 9 Development of a Design FMEA ............................................................................................................... 10 1) 2) 3) 4) 5) 6) 7) 8) 9) 10) 11) 12) 13) 14) 15) 16) 17) 18) 19) 20) 21) 22)

FMEA Number ........................................................................................................................ System, Subsystem, or Component Name and Number ....................................................... Design Responsibility ............................................................................................................. Prepared By ............................................................................................................................ Model Year(s)/Program(s) ...................................................................................................... Key Date ................................................................................................................................. FMEA Date ............................................................................................................................. Core Team .............................................................................................................................. Item/Function .......................................................................................................................... Potential Failure Mode ........................................................................................................... Potential Effect(s) of Failure ................................................................................................... Severity (S) ............................................................................................................................. Suggested Evaluation Criteria ................................................................................................ Classification .......................................................................................................................... Potential Cause(s)/Mechanism(s) of Failure .......................................................................... Occurrence (O) ....................................................................................................................... Suggested Evaluation Criteria ................................................................................................ Current Design Controls ......................................................................................................... Detection (D) .......................................................................................................................... Suggested Evaluation Criteria ................................................................................................ Risk Priority Number (RPN) ................................................................................................... Recommended Action(s) ........................................................................................................ Responsibility for the Recommended Action(s) ..................................................................... Action(s) Taken ...................................................................................................................... Action Results .........................................................................................................................

13 13 13 13 13 13 13 15 15 15 17 17 19 19 19 21 23 25 25 27 27 29 29 31 31

Follow-Up Actions ...................................................................................................................................... 31 Process FMEA .......................................................................................................................................... 33 Introduction ................................................................................................................................................ 35 Customer Defined ......................................................................................................................... 35 Team Effort ................................................................................................................................... 35 –I–

TABLE OF CONTENTS - continued Page Number Development of a Process FMEA ............................................................................................................. 37 1) 2) 3) 4) 5) 6) 7) 8) 9) 10) 11) 12) 13) 14) 15) 16) 17) 18) 19) 20) 21) 22)

FMEA Number ......................................................................................................................... Item ......................................................................................................................................... Process Responsibility ............................................................................................................ Prepared By ............................................................................................................................ Model Year(s)/Program(s) ...................................................................................................... Key Date .................................................................................................................................. FMEA Date .............................................................................................................................. Core Team .............................................................................................................................. Process Function/Requirements ............................................................................................. Potential Failure Mode ............................................................................................................ Potential Effect(s) of Failure .................................................................................................... Severity (S) .............................................................................................................................. Suggested Evaluation Criteria ................................................................................................ Classification ........................................................................................................................... Potential Cause(s)/Mechanism(s) of Failure ........................................................................... Occurrence (O) ....................................................................................................................... Suggested Evaluation Criteria ................................................................................................ Current Process Controls ........................................................................................................ Detection (D) ........................................................................................................................... Suggested Evaluation Criteria ................................................................................................ Risk Priority Number (RPN) .................................................................................................... Recommended Action(s) ......................................................................................................... Responsibility for the Recommended Action(s) ...................................................................... Action(s) Taken ....................................................................................................................... Action Results ..........................................................................................................................

37 39 39 39 39 39 39 39 39 39 41 41 43 45 45 47 47 49 51 53 53 55 57 57 57

Follow-Up Actions ...................................................................................................................................... 57

APPENDICES A B C D E F G H I

Design FMEA Quality Objectives ............................................................................................ Process FMEA Quality Objectives ........................................................................................... Design FMEA Block Diagram Example ................................................................................... Standard Forms for Design FMEA (1 and 2 column for controls) ........................................... Design FMEA Example ............................................................................................................ System FMEA .......................................................................................................................... Standard Forms for Process FMEA (1 and 2 column for controls) .......................................... Process FMEA Example .......................................................................................................... Occurrence Evaluation Criteria With Cpk Values ....................................................................

– Il –

59 60 61 62 64 65 68 70 71

– Ill –

GENERAL INFORMATION Overview

This manual introduces the topic of Potential Failure Mode and Effects Analysis (FMEA) and gives general guidance in the application of the technique.

What Is an FMEA

An FMEA can be described as a systematic group of activities intended to: (a) recognize and evaluate the potential failure of a product/process and the effects of that failure, (b) identify actions that could eliminate or reduce the chance of the potential failure occurring, and (c) document the entire process. It is complementary to the process of defining what a design or process must do to satisfy the customer. All FMEAs focus on the design, whether it be of the product, or process.

Manual Format

This reference document presents two types of FMEA: Design FMEA, and Process FMEA. This manual should be used by suppliers that subscribe to QS9000 or its equivalent. FMEA teams are allowed to use the guidelines listed herein in the manner that will be most effective for a given situation.

–1–

FMEA Implementation

Because of the general industry trend to continually improve products and processes whenever possible, using the FMEA as a disciplined technique to identify and help minimize potential concern is as important as ever. Studies of vehicle campaigns have shown that fully implemented FMEA programs could have prevented many of the campaigns. One of the most important factors for the successful implementation of an FMEA program is timeliness. It is meant to be a “before-the-event” action, not an “after-the-fact” exercise. To achieve the greatest value, the FMEA must be done before a product or process failure mode has been incorporated into a product or process. Up-front time spent properly completing an FMEA, when product/process changes can be most easily and inexpensively implemented, will minimize late change crises. An FMEA can reduce or eliminate the chance of implementing a preventive/corrective change that would create an even larger concern. Communication and coordination should occur among all FMEA teams. Figure 1 depicts the sequence in which an FMEA should be performed. It is not simply a case of filling out the form but rather of understanding the FMEA process in order to eliminate risk and plan the appropriate controls to ensure customer satisfaction. There are three basic cases for which FMEA's are generated, each with a different scope or focus: Case 1:

New designs, new technology, or new process. The scope of the FMEA is the complete design, technology, or process.

Case 2:

Modifications to existing design 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 process, possible interactions due to the modification, and field history.

Case 3:

Use of existing design 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.

Although responsibility for the preparation of the FMEA is usually assigned to an individual, FMEA input should be a team effort. A team of knowledgeable individuals should be assembled (e.g., engineers with expertise in design, analysis/ testing, manufacturing, assembly, service, recycling, quality, and reliability). The FMEA is initiated by the engineer from the responsible activity, which can be the Original Equipment Manufacturer (i.e., produces the final product), a supplier, or a subcontractor.

–2–

–3–

Potential Failure Mode

- Unintended Function

- Intermittent Function

- Partial/Over/ Degraded Function

- No Function

What can go wrong?

What are the Functions, Features or Requirements?

Function Reqt's

Subsystem

What are the Effect(s)?

Potential Effect(s) of Failure

Potential Cause(s)/ Mechanism(s) of Failure

What are the Cause(s)?

How bad is it?

C S l e a v s s

O c c u r Detection

How can this be prevented and detected?

How often does it happen?

Prevention

Current Controls Responsibility & Target Completion Date

- Changes to Standards, Procedures, or Guides

- Special Controls

- Process Changes

- Design Changes

What can be done?

Recommended Action(s)

How good is this method at detecting it?

D e R. t P. e N. c

POTENTIAL FAILURE MODE AND EFFECTS ANALYSIS SEQUENCE

Actions Taken

S O D e c e v c t

Action Results R. P. N.

Figure 1. FMEA Process Sequence

It is not appropriate to compare the ratings of one team’s FMEA with the ratings of another team’s FMEA, even if the product/ process appears to be identical, since each team's environment is unique and thus the respective individual ratings will be unique (i.e., the ratings are subjective). A review of the FMEA document against FMEA quality objectives (see Appendix A and Appendix B) is recommended, including a management review.

Follow-Up

The need for taking effective preventive/corrective actions, with appropriate follow-up on those actions, cannot be overemphasized. Actions should be communicated to all affected activities. A thoroughly thought-out and well-developed FMEA will be of limited value without positive and effective preventive/corrective actions. The responsible engineer is in charge of ensuring that all recommended actions have been implemented or adequately addressed. The FMEA is a living document and should always reflect the latest level, as well as the latest relevant actions, including those occurring after the start of production. The responsible engineer has several means of assuring that recommended actions are implemented. They include, but are not limited to the following: a. Reviewing designs, processes, and, drawings, to ensure that recommended actions have been implemented. b. Confirming the incorporation of changes to design/assembly/ manufacturing documentation. c. Reviewing Design/Process FMEAs, applications, and Control Plans.

–4–

special

FMEA

–5–

–6–

DESIGN FMEA

POTENTIAL FAILURE MODE AND EFFECTS ANALYSIS IN DESIGN (DESIGN FMEA)

–7–

–8–

DESIGN FMEA INTRODUCTION A Design Potential FMEA is an analytical technique used primarily by a Design-Responsible Engineer/Team as a means to ensure that, to the extent possible, potential failure modes and their associated causes/mechanisms have been considered and addressed. End items, along with every related system, subassembly, and component, should be evaluated. In its most rigorous form, an FMEA is a summary of the team’s thoughts (including an analysis of items that could go wrong based on experience) as a component, subsystem, or system is designed. This systematic approach parallels, formalizes, and documents the mental disciplines that an engineer normally goes through in any design process. The Design Potential FMEA supports the design process in reducing the risk of failures (including unintended outcomes) by: • • • • •

• •

Aiding in the objective evaluation of design, including functional requirements and design alternatives, Evaluating the initial design for manufacturing, assembly, service, and recycling requirements, Increasing the probability that potential failure modes and their effects on system and vehicle operation have been considered in the design/development process, Providing additional information to aid in the planning of thorough and efficient design, development, and validation programs, Developing a ranked list of potential failure modes according to their effect on the “customer,” thus establishing a priority system for design improvements, development, and validation testing/analysis, Providing an open issue format for recommending and tracking risk-reducing actions, and, Providing future reference, e.g., lessons learned, to aid in analyzing field concerns, evaluating design changes, and developing advanced designs.

Customer Defined

The definition of “Customer” for a Design FMEA is not only the “End User” but also the design-responsible engineers/teams of the vehicle or higher-level assemblies, and/or the manufacturing/process-responsible engineers in activities such as manufacturing, assembly, and service.

Team Effort

During the initial Design FMEA process, the responsible engineer is expected to directly and actively involve representatives from all affected areas. These areas of expertise and responsibility should include but are not limited to assembly, manufacturing, design, analysis/test, reliability, materials, quality, service, and suppliers, as well as the design area responsible for the next higher or lower assembly or system, sub-assembly, or component. The FMEA should be a catalyst to stimulate the interchange of ideas between the functions affected and thus promote a team approach. –9–

DESIGN FMEA Unless the responsible engineer is experienced with FMEA and team facilitation, it is helpful to have an experienced FMEA facilitator assist the team in its activities. The Design FMEA is a living document and should: • Be initiated before or at design concept finalization, • Be continually updated as changes occur or additional information is obtained throughout the phases of product development, and • Be fundamentally completed before the production drawings are released for tooling. Considering that manufacturing/assembly needs have been incorporated, the Design FMEA addresses the design intent and assumes the design will be manufactured/assembled to this intent. Potential failure modes and/or causes/mechanisms that can occur during the manufacturing or assembly process need not but may be included in a Design FMEA. When not included, their identification, effect, and control are covered by the Process FMEA. The Design FMEA does not rely on process controls to overcome potential design weaknesses, but it does take the technical/physical limits of a manufacturing/assembly process into consideration, for example: • • • • •

Necessary mold drafts Limited surface finish Assembling space/access for tooling Limited hardenability of steels Tolerances/process capability/performance

The Design FMEA can also take into consideration the technical/physical limits of product maintenance (service) and recycling, for example: • • •

Tool access Diagnostic capability Material classification symbols (for recycling)

DEVELOPMENT OF A DESIGN FMEA The design-responsible engineer has at his or her disposal a number of documents that will be useful in preparing the Design FMEA. The process begins by developing a listing of what the design is expected to do and what it is expected not to do, i.e., the design intent. Customer wants and needs — as may be determined from sources such as Quality Function Deployment (QFD), Vehicle Requirements Documents, known product requirements, and/or manufacturing/assembly/service/recycling requirements — should be incorporated. The better the definition of the desired characteristics, the easier it is to identify potential failure modes for preventive/corrective action. A Design FMEA should begin with a block diagram for the system, subsystem, and/or component being analyzed. – 10 –

DESIGN FMEA An example block diagram is shown in Appendix C. The block diagram can also indicate the flow of information, energy, force, fluid, etc. The object is to understand the deliverables (input) to the block, the process (function) performed in the block, and the deliverables (output) from the block. The diagram illustrates the primary relationship among the items covered in the analysis and establishes a logical order to the analysis. Copies of the diagrams used in FMEA preparation should accompany the FMEA. In order to facilitate documentation of the analysis of potential failures and their consequences, a blank Design FMEA form is available in Appendix D.

– 11 –

Component 01.03/Body Closures

Subsystem

5

2

Function

9

– 12 –

• Support anchorage for door hardware including mirror, hinges, latch and window regulator • Provide proper surface for appearance items - Paint and soft trim

• Ingress to and egress from vehicle • Occupant protection from weather, noise, and side impact

12 C S l e a v s s

7

7

7

Deteriorated life of 7 door leading to: • Unsatisfactory appearance due to rust througH paint over time • Impaired function 7 of interior door hardware

11


▲

Corroded interior lower door panels

10


O c c u r

17

18

19


20

Responsibility & Target Completion Date

4

SAMPLE

Body Engrg & Assy Ops 8X 09 15

4 112 Add team evaluation using design aid buck and spray head

Insufficient room between panels for spray head access\

None

Drawing evaluation of spray head access

28

A Tate Body Engrg 9X 01 15

8 280 Add team Body Engrg & evaluation using Assy Ops production spray 8X 11 15 equipment and specified wax

2

Conduct Design of Experiments (DOE) on wax thickness

7 196 Add laboratory Combine w/test accelerated for wax upper corrosion testing edge verification

7 294 Add laboratory A Tate-Body accelerated Engrg corrosion testing 8X 09 30

D e R. t P. e N. c

Design aid investigation with non-functioning spray head

Vehicle general durability testing- as above

Vehicle general durability test veh. T-118 T-109 T-301

16

Current Design Controls Detection

1

21

Evaluation showed adequate access

Based on test, 3 additional vent holes provided in affected areas

7

7

7 Test results (Test No. 1481) show specified thickness is adequate. DOE shows 25% variation in specified thickness is acceptable.

7

1

1

2

2

1

3

2

2

7

21

28

28

R. P. N.

22 S O D e c e v c t

Action Results Actions Taken

8

(Rev.) 8X 07 14

Based on test results (Test No. 1481) upper edge spec raised 125mm

FMEA Date (Orig.) 8X 03 22

Entrapped air prevents 5 wax from entering corner/edge access

16

Current Design Controls Prevention

of 1

1234

Prepared By A. Tate - X6412- Body Engr

Page 1

FMEA Number

Physical and Chem Lab test- Report No.1265

4

15

6

3

▲

2 Inappropriate wax formulation specified

Insufficient wax thickness specified

6 Upper edge of protective wax application specified for inner door panels is too low

14


13

(Dalton, Fraser, Henley Assembly Plants)

Key Date 9X 03 01 ER

Design Responsibility Body Engineering

▲

Front Door L.H. H8HX-0000-A

Item

▲

Core Team T. Fender-Car Product Dev., Childers-Manufacturing, J. Ford-Assy Ops

MODEL YEARS(S)/Vehicle(s) 199X/Lion 4dr/Wagon

X

POTENTIAL FAILURE MODE AND EFFECTS ANALYSIS (DESIGN FMEA)

▲

System

7

4

TABLE 1. DESIGN FMEA

DESIGN FMEA 1)

FMEA Number

Enter the FMEA document number, which may be used for tracking. Note:

2)

System, Subsystem, or Component Name and Number

For an example of items 1-22 see Table 1.

Indicate the appropriate level of analysis and enter the name and number of the system, subsystem, or component being analyzed. The FMEA team members must decide on what constitutes a system, subsystem, or component for their specific activities. The actual boundaries that divide a system, subsystem, and component are arbitrary and must be set by the FMEA team. Some descriptions are provided below and some examples are provided in Appendix F. System FMEA Scope A system can be considered to be made up of various subsystems. These subsystems often have been designed by different teams. Some typical System FMEAs might cover the following systems: Chassis System, or Powertrain System, or Interior System, etc. Thus, the focus of the System FMEA is to ensure that all interfaces and interactions are covered among the various subsystems that make up the system as well as interfaces to other vehicle systems and the customer. Subsystem FMEA Scope A Subsystem FMEA is generally a sub-set of a larger system. For example, the front suspension subsystem is a sub-set of the chassis system. Thus, the focus of the Subsystem FMEA is to ensure that all interfaces and interactions are covered among the various components that make up the subsystem. Component FMEA Scope A Component FMEA is a generally an FMEA focused on the sub-set of a subsystem. For example, a strut is a component of the front suspension (which is a subsystem of the chassis system.)

3)

Design Responsibility

Enter the OEM, department, and group. Also include the supplier name, if applicable.

4)

Prepared By

Enter the name, telephone number, and company of the engineer responsible for preparing the FMEA.

5)

Model Year(s)/Program(s)

Enter the intended model year(s)/program(s) that will use and/or be affected by the design being analyzed (if known).

6)

Key Date

Enter the initial FMEA due date, which should not exceed the scheduled production design release date.

7)

FMEA Date

Enter the date the original FMEA was compiled and the latest revision date.

– 13 –


Subsystem

5

2

Function

9

– 14 –



12 C S l e a v s s

7

7

7


11


▲


10


O c c u r

17

18

19


20


4

SAMPLE




None


28



2




D e R. t P. e N. c




16


1

21



7

7


7

1

1

2

2

1

3

2

2

7

21

28

28

R. P. N.



8

(Rev.) 8X 07 14




16


of 1

1234


Page 1

FMEA Number


4

15

6

3

▲




14


13




▲


Item

▲



X


▲

System

7

4


DESIGN FMEA 8)

Core Team

List the names of the responsible individuals and departments that have the authority to identify and/or perform tasks. (It is recommended that each team member's name, department, telephone number, addresse, etc., be included on a distribution list.)

9)

Item/Function

Enter the name and other pertinent information (e.g., the number, the part class, etc.) of the item being analyzed. Use the nomenclature and show the design level as indicated on the engineering drawing. Prior to initial release (e.g., in the conceptual phases), experimental numbers should be used. Enter, as concisely as possible, the function of the item being analyzed to meet the design intent. Include information (metrics/ measurables) regarding the environment in which this system operates (e.g., define temperature, pressure, humidity ranges, design life). If the item has more than one function with different potential modes of failure, list all the functions separately.

10) Potential Failure Mode

Potential failure mode is defined as the manner in which a component, subsystem, or system could potentially fail to meet or deliver the intended function described in the item/function column (i.e., intended function fails). The potential failure mode may also be the cause of a potential failure mode in a higherlevel subsystem or system, or be the effect of one in a lowerlevel component. List each potential failure mode associated with the particular item and item function. The assumption is made that the failure could occur but may not necessarily occur. A recommended starting point is a review of past things-gone-wrong, concerns, reports, and group brainstorming. Potential failure modes that could occur only under certain operating conditions (i.e., hot, cold, dry, dusty, etc.) and under certain usage conditions (i.e., above-average mileage, rough terrain, city driving only, etc.) should be considered. Typical failure modes could be but are not limited to: Cracked Loosened Sticking Fractured Slips (does not hold full torque) Inadequate support (structural) Disengages too fast Intermittent signal EMC/RFI NOTE:

Deformed Leaking Oxidized Does not transmit torque No support (structural) Harsh engagement Inadequate signal No signal Drift

Potential failure modes should be described in “physical” or technical terms, not as a symptom necessarily noticeable by the customer.

– 15 –


Subsystem

5

2

Function

9

– 16 –



12 C S l e a v s s

7

7

7


11


▲


10


O c c u r

17

18

19


20


4

SAMPLE




None


28



2




D e R. t P. e N. c




16


1

21



7

7


7

1

1

2

2

1

3

2

2

7

21

28

28

R. P. N.



8

(Rev.) 8X 07 14




16


of 1

1234


Page 1

FMEA Number


4

15

6

3

▲




14


13




▲


Item

▲



X


▲

System

7

4


DESIGN FMEA 11) Potential Effect(s) of Failure Potential effects of failure are defined as the effects of the failure mode on the function, as perceived by the customer. Describe the effects of the failure in terms of what the customer might notice or experience, remembering that the customer may be an internal customer as well as the ultimate end user. State clearly if the failure mode could impact safety or noncompliance to regulations. The effects should always be stated in terms of the specific system, subsystem, or component being analyzed. Remember that a hierarchical relationship exists between the component, subsystem, and system levels. For example, a part could fracture, which may cause the assembly to vibrate, resulting in an intermittent system operation. The intermittent system operation could cause performance to degrade and ultimately lead to customer dissatisfaction. The intent is to forecast the failure effects, to the team’s level of knowledge. Typical failure effects could be but are not limited to: Noise Erratic Operation Poor Appearance Unstable Intermittent Operation Leaks

12) Severity (s)

Rough Inoperative Unpleasant Odor Operation Impaired Thermal Event Regulatory Non-Compliance

Severity is the rank associated with the most serious effect for a given failure mode. Severity is a relative ranking within the scope of the individual FMEA. A reduction in the severity ranking index can be effected only through a design change. Severity should be estimated using Table 2 as a guideline: Suggested Evaluation Criteria The team should agree on an evaluation criteria and ranking system that is consistent, even if modified for individual product analysis. (See Table 2.) NOTE:

It is not recommended to modify criteria ranking values of 9 and 10. Failure modes with a rank of severity 1 should not be analyzed further.

NOTE:

High severity rankings can sometimes be reduced by making design revisions that compensate or mitigate the resultant severity of failure. For example, “run flat tires” can mitigate the severity of a sudden tire blowout and “seat belts” can mitigate the severity of a vehicle crash.

– 17 –


Subsystem

5

2

Function

9

– 18 –



12 C S l e a v s s

7

7

7


11


▲


10


O c c u r

17

18

19


20


4

SAMPLE




None


28



2




D e R. t P. e N. c




16


1

21



7

7


7

1

1

2

2

1

3

2

2

7

21

28

28

R. P. N.



8

(Rev.) 8X 07 14




16


of 1

1234


Page 1

FMEA Number


4

15

6

3

▲




14


13




▲


Item

▲



X


▲

System

7

4

Table 1. DESIGN FMEA

DESIGN FMEA 12) Severity (S) (continued)

Table 2. Suggested DFMEA Severity Evaluation Criteria Criteria: Severity of Effect

Effect Hazardous without warning

Very high severity ranking when a potential failure mode affects safe vehicle operation and/or involves noncompliance with government regulation without warning.

Ranking 10

Hazardous Very high severity ranking when a potential failure mode affects safe vehicle with warning operation and/or involves noncompliance with government regulation with warning.

9

Very High

Vehicle/item inoperable (loss of primary function).

8

High

Vehicle/item operable but at reduced level of performance. Customer very dissatisfied.

7

Moderate

Vehicle/item operable, but Comfort/Convenience item(s) inoperable. Customer dissatisfied.

6

Low

Vehicle/item operable, but Comfort/Convenience item(s) operable at a reduced level of performance. Customer somewhat dissatisfied.

5

Very Low

Fit & Finish/Squeak & Rattle item does not conform. Defect noticed by most customers (greater than 75%).

4

Minor

Fit & Finish/Squeak & Rattle item does not conform. Defect noticed by 50% of customers.

3

Very Minor

Fit & Finish/Squeak & Rattle item does not conform. Defect noticed by discriminating customers (less than 25%).

2

None

No discernible effect.

1

13)

Classification

This column may be used to classify any special product characteristics (e.g., critical, key, major, significant) for components, subsystems, or systems that may require additional design or process controls. This column may also be used to highlight high-priority failure modes for engineering assessment if the team finds this helpful or if local management requires it. Special product or process characteristic symbols and their usage is directed by specific company policy and is not standardized in this document.

14) Potential Cause(s)/ Mechanism(s) of Failure

Potential cause of failure is defined as an indication of a design weakness, the consequence of which is the failure mode. List, to the extent possible, every potential cause and/or failure mechanism for each failure mode. The cause/mechanism should be listed as concisely and completely as possible so that remedial efforts can be aimed at pertinent causes.

– 19 –


Subsystem

5

2

Function

9

– 20 –



12 C S l e a v s s

7

7

7


11


▲


10


O c c u r

17

18

19


20


4

SAMPLE




None


28



2




D e R. t P. e N. c




16


1

21



7

7


7

1

1

2

2

1

3

2

2

7

21

28

28

R. P. N.



8

(Rev.) 8X 07 14




16


of 1

1234


Page 1

FMEA Number


4

15

6

3

▲




14


13




▲


Item

▲



X


▲

System

7

4


DESIGN FMEA 14) Potential Cause(s)/ Mechanism(s) of Failure (continued)

Typical failure causes may include, but are not limited to: Incorrect Material Specified Inadequate Design Life Assumption Over-stressing Insufficient Lubrication Capability Inadequate Maintenance Instructions Incorrect Algorithm Improper Maintenance Instructions Improper Software Specification Improper Surface Finish Specification Inadequate Travel Specification Improper Friction Material Specified Excessive Heat Improper Tolerance Specified Typical failure mechanisms may include but are not limited to: Yield Chemical Oxidation Fatigue Electromigration Material Instability Creep Wear Corrosion

15) Occurrence (O)

Occurrence is the likelihood that a specific cause/mechanism will occur during the design life. The likelihood of occurrence ranking number has a relative meaning rather than an absolute value. Preventing or controlling the causes/mechanisms of the failure mode through a design change or design process change (e.g., design checklist, design review, design guide) is the only way a reduction in the occurrence ranking can be effected. (See Table 3.) Estimate the likelihood of occurrence of potential failure cause/ mechanism on a 1 to 10 scale. In determining this estimate, questions such as the following should be considered: • • • • • • • • •

What is the service history/field experience with similar components, subsystems, or systems? Is the component a carryover or similar to a previous level component, subsystem or system? How significant are changes from a previous level component, subsystem, or system? Is the component radically different from a previous level component? Is the component completely new? Has the component application changed? What are the environmental changes? Has an engineering analysis (e.g., reliability) been used to estimate the expected comparable occurrence rate for the application? Have preventive controls been put in place?

– 21 –


Subsystem

5

2

Function

9

– 22 –



12 C S l e a v s s

7

7

7


11


▲


10


O c c u r

17

18

19


20


4

SAMPLE




None


28



2




D e R. t P. e N. c




16


1

21



7

7


7

1

1

2

2

1

3

2

2

7

21

28

28

R. P. N.



8

(Rev.) 8X 07 14




16


of 1

1234


Page 1

FMEA Number


4

15

6

3

▲




14


13




▲


Item

▲



X


▲

System

7

4


DESIGN FMEA 15) Occurrence (O) (continued)

A consistent occurrence ranking system should be used to ensure continuity. The occurrence ranking number is a relative rating within the scope of the FMEA and may not reflect the actual likelihood of occurrence. Suggested Evaluation Criteria The team should agree on an evaluation criteria and ranking system, that is consistent, even if modified for individual product analysis. (See Table 3.) Occurrence should be estimated using Table 3 as a guideline: NOTE:

The ranking value of 1 is reserved for “Remote: Failure Is unlikely.”

TABLE 3. Suggested DFMEA Occurrence Evaluation Criteria Probability of Failure Very High: Persistent failures

High: Frequent failures

Moderate: Occasional failures

Low: Relatively few failures

Remote: Failure is unlikely

16) Current Design Controls

Possible Failure Rates

Ranking

> 100 per thousand vehicles/items

10

50 per thousand vehicles/items

9


8


7


6


5


4

0.5 per thousand vehicles/items

3

0.1 per thousand vehicles/items

2

< 0.010 per thousand vehicles/items

1

List the prevention, design validation/verification (DV), or other activities that have been completed or committed to and that will assure the design adequacy for the failure mode and/or cause/mechanism under consideration. Current controls (e.g., design reviews, fail/safe designs such as a pressure relief valve, mathematical studies, rig/lab testing, feasibility review, prototype tests, road testing, fleet testing) are those that have been or are being used with the same or similar designs. The team should always be focused on improving design controls; for example, creating new system tests in the lab, or creating new system modeling algorithms, etc. There are two types of design controls to consider: Prevention: Prevent the cause/mechanism of failure or the failure mode from occurring, or reduce their rate of occurrence, Detection: Detect the cause/mechanism of failure or the failure mode, either by analytical or physical methods, before the item is released to production. – 23 –


Subsystem

5

2

Function

9

– 24 –



12 C S l e a v s s

7

7

7


11


▲


10


O c c u r

17

18

19


20


4

SAMPLE




None


28



2




D e R. t P. e N. c




16


1

21



7

7


7

1

1

2

2

1

3

2

2

7

21

28

28

R. P. N.



8

(Rev.) 8X 07 14




16


of 1

1234


Page 1

FMEA Number


4

15

6

3

▲




14


13




▲


Item

▲



X


▲

System

7

4


DESIGN FMEA 16)

Current Design Controls (continued)

The preferred approach is to first use prevention controls, if possible. The initial occurrence rankings will be affected by the prevention controls provided they are integrated as part of the design intent. The initial rankings for detection will be based on design controls that either detect the cause/mechanism of failure, or detect the failure mode. The Design FMEA form in this manual has two columns for the design controls (i.e., separate columns for Prevention Controls and Detection Controls) to assist the team in clearly distinguishing between these two types of design controls. This allows for a quick visual determination that both types of design controls have been considered. Use of this two-column form is the preferred approach. Note:

In the example included here, it is clear that the team has not identified any prevention controls. This could be due to prevention controls not having been used on the same or similar designs.

If a one-column (for design controls) form is used, then the following prefixes should be used. For prevention controls, place a 'P' before each prevention control listed. For detection controls, place a 'D' before each detection control listed. Once the design controls have been identified, review all prevention controls to determine if any occurrence rankings need to be revised.

17) Detection (D)

Detection is the rank associated with the best detection control listed in the design control. 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.

– 25 –


Subsystem

5

2

Function

9

– 26 –



12 C S l e a v s s

7

7

7


11


▲


10


O c c u r

17

18

19


20


4

SAMPLE




None


28



2




D e R. t P. e N. c




16


1

21



7

7


7

1

1

2

2

1

3

2

2

7

21

28

28

R. P. N.



8

(Rev.) 8X 07 14




16


of 1

1234


Page 1

FMEA Number


4

15

6

3

▲




14


13




▲


Item

▲



X


▲

System

7

4


DESIGN FMEA Suggested Evaluation Criteria The team should agree on an evaluation criteria and ranking system that is consistent, even if modified for individual product analysis. It is best to have detection controls in place as early as possible in the design development process. NOTE:

After making the detection ranking, the team should review the occurrence ranking and ensure that the occurrence ranking is still appropriate.

Detection should be estimated using Table 4 as a guideline. NOTE:

The ranking value of 1 is reserved for “almost certain.”

TABLE 4. Suggested Detection Evaluation Criteria Detection Absolute Uncertainty

Criteria: Likelihood of Detection by Design Control Design Control will not and/or can not detect a potential cause/mechanism and subsequent failure mode; or there is no Design Control.

Ranking 10

Very Remote Very remote chance the Design Control will detect a potential cause/mechanism and subsequent failure mode.

9

Remote

Remote chance the Design Control will detect a potential cause/mechanism and subsequent failure mode.

8

Very Low

Very low chance the Design Control will detect a potential cause/mechanism and subsequent failure mode.

7

Low

Low chance the Design Control will detect a potential cause/mechanism and subsequent failure mode.

6

Moderate

Moderate chance the Design Control will detect a potential cause/mechanism and subsequent failure mode.

5

Moderately High

Moderately high chance the Design Control will detect a potential cause/ mechanism and subsequent failure mode.

4

High

High chance the Design Control will detect a potential cause/mechanism and subsequent failure mode.

3

Very High

Very high chance the Design Control will detect a potential cause/mechanism and subsequent failure mode.

2

Almost Certain

Design Control will almost certainly detect a potential cause/mechanism and subsequent failure mode.

1

18) Risk Priority Number (RPN) The risk priority number is the product of the severity (S), occurrence (O), and detection (D) rankings. (S) x (O) x (D) = RPN Within the scope of the individual FMEA, this value (between 1 and 1000) can be used to rank order the concerns in the design.

– 27 –


Subsystem

5

2

Function

9

– 28 –



12 C S l e a v s s

7

7

7


11


▲


10


O c c u r

17

18

19


20


4

SAMPLE




None


28



2




D e R. t P. e N. c




16


1

21



7

7


7

1

1

2

2

1

3

2

2

7

21

28

28

R. P. N.



8

(Rev.) 8X 07 14




16


of 1

1234


Page 1

FMEA Number


4

15

6

3

▲




14


13




▲


Item

▲



X


▲

System

7

4


DESIGN FMEA 19) Recommended Action(s)

Engineering assessment for preventive/corrective action should be first directed at high severity, high RPN, and other items designated by the team. The intent of any recommended action is to reduce rankings in the following order: severity, occurrence, and detection. In general practice when the severity is a 9 or 10, special attention must be given to ensure that the risk is addressed through existing design controls or preventive/corrective action(s), regardless of the RPN. In all cases where the effect of an identified potential failure mode could be a hazard to the end user, preventive/corrective actions should be considered to avoid the failure mode by eliminating, mitigating, or controlling the cause(s). After special attention has been given to severity rankings of 9 or 10, the team then addresses other failure modes, with the intent of reducing severity, then occurrence, and then detection. Actions such as, but not limited to, the following should be considered: • • • •

Revised Design Geometry and/or Tolerances, Revised Material Specification, Design of Experiments (particularly when multiple or interactive causes are present) or other problem-solving techniques, and, Revised Test Plan.

The primary objective of recommended actions is to reduce risks and increase customer satisfaction by improving the design. Only a design revision can bring about a reduction in the severity ranking. A reduction in the occurrence ranking can be effected only by removing or controlling one or more of the causes/mechanisms of the failure mode through a design revision. An increase in design validation/verification actions will result in a reduction in the detection ranking only. Increasing the design validation/verification actions is a less desirable engineering action since it does not address the severity or occurrence of the failure mode. If engineering assessment leads to no recommended actions for a specific failure mode/cause/control combination, indicate this by entering “None” in this column.

20) Responsibility for the Recommended Action(s)

Enter the name of organization and individual responsible for each recommended action and the target completion date.

– 29 –


Subsystem

5

2

Function

9

– 30 –



12 C S l e a v s s

7

7

7


11


▲


10


O c c u r

17

18

19


20


4

SAMPLE




None


28



2




D e R. t P. e N. c




16


1

21



7

7


7

1

1

2

2

1

3

2

2

7

21

28

28

R. P. N.



8

(Rev.) 8X 07 14




16


of 1

1234


Page 1

FMEA Number


4

15

6

3

▲




14


13




▲


Item

▲



X


▲

System

7

4

DESIGN FMEA

DESIGN FMEA 21) Action(s) Taken

After the action has been implemented, enter a brief description of the actual action and effective date.

22) Action Results

After the preventive/corrective action has been identified, estimate and record the resulting severity, occurrence, and detection rankings. Calculate and record the resulting RPN. If no actions are taken, leave the related ranking columns blank. All revised ratings should be reviewed. If further action is considered necessary, repeat the analysis. The focus should always be on continuous improvement.

Follow-Up Actions The design-responsible engineer is responsible for ensuring that all actions recommended have been implemented or adequately addressed. The FMEA is a living document and should always reflect the latest design level as well as the latest relevant actions, including those occurring after start of production. The design-responsible engineer has several means of ensuring that concerns are identified and that recommended actions are implemented. They include, but are not limited to the following: • • • •

Ensuring design requirements are achieved, Reviewing engineering drawings and specifications, Confirming incorporation in assembly/manufacturing documentation, and, Reviewing Process FMEAs and Control Plans.

– 31 –

– 32 –

PROCESS FMEA

POTENTIAL FAILURE MODE AND EFFECTS ANALYSIS IN MANUFACTURING AND ASSEMBLY PROCESSES (PROCESS FMEA)

– 33 –

– 34 –

PROCESS FMEA INTRODUCTION A Process Potential FMEA is an analytical technique used by a Manufacturing/Assembly-Responsible Engineer/Team as a means to ensure that, to the extent possible, potential failure modes and their associated causes/mechanisms have been considered and addressed. In its most rigorous form, an FMEA is a summary of the team’s thoughts (including an analysis of items that could go wrong based on experience) as a process is developed. This systematic approach parallels and formalizes the mental discipline that an engineer normally goes through in any manufacturing planning process. The Process Potential FMEA: • • • •

• • •

Customer Defined

Identifies the process functions and requirements Identifies potential product and process-related failure modes, Assesses the effects of the potential failures on the customer, Identifies the potential manufacturing or assembly process causes and identifies process variables on which to focus controls for occurrence reduction or detection of the failure conditions, Identifies process variables on which to focus process controls, Develops a ranked list of potential failure modes, thus establishing a priority system for preventive/corrective action considerations, and, Documents the results of the manufacturing or assembly process.

The definition of “Customer” for a Process FMEA should normally be the “End User.” However, the customer can also be a subsequent or downstream manufacturing or assembly operation, a service operation, or government regulations.

.

Team Effort

During the initial development of the Process FMEA, the responsible engineer is expected to directly and actively involve representatives from all affected areas. These areas should include but are not limited to design, assembly, manufacturing, materials, quality, service, and suppliers, as well as the area responsible for the next assembly. The Process FMEA should be a catalyst to stimulate the interchange of ideas between the areas affected and thus promote a team approach. Unless the responsible engineer is experienced with FMEA and team facilitation, it is helpful to have an experienced FMEA facilitator assist the team in its activities.

– 35 –

Front Door L.H./H8HX-000-A

5

2

11

10

12



▲

To cover inner door, lower surfaces at minimum wax thickness to retard corrosion

Deteriorated life of Insufficient Manual wax coverage door leading to: application of wax inside door over specified • Unsatisfactory appearance due surface to rust through paint over time • Impaired function of interior doo hardware

Requirements

9

Process Function

Spray heads clogged - Viscosity too high - Temperature too low - Pressure too low

Spray head deformed due to impact

Spray time insufficient

7

7

15 Current Process Controls Prevention

– 36 – 8

17

SAMPLE

Operator instructions and lot sampling (10 doors / shift) to check for coverage of critical areas

Visual check each hour1/shift for film thickness (depth meter) and coverage



16

Current Process Controls Detection

9X 08 26 Job #1

2 Preventive maintenance programs to maintain heads

5 Test spray pattern at start-up and after idle periods, and preventive maintenance program to clean heads

8

Manually inserted spray head not inserted far enough

14

O c c u r

13 Potential Cause(s)/ Mechanism(s) of Failure

▲

7

7

C S l e a v s s

16


Process Responsibility Body Engrg.

▲

Core Team A. Tate Body Engrg., J. Smith-OC, R. James-Production, J. Jones-Maintenance

Model Years(S)/Vehicle(s) 199X/Lion 4dr/Wagon

Item

POTENTIAL FAILURE MODE AND EFFECTS ANALYSIS (PROCESS FMEA)

18

19

70 None

7 392 Install spray timer

5

Maintenance 9X 09 15

Mfg Engrg 9X 10 01

Mfg Engrg 9X 12 15

MFG Engrg 9X 10 15

20


1

21

Actions Taken

Automatic spray timer installed operator starts spray, timer controls shut-off control charts show process is in control Cpk=2.05

Temp and press limits were determined and limit controls have been installed control charts show process is in control Cpk=1.85

Rejected due to complexity of different doors on same line

7

7

7

1

1

2

7

5

5

49

35

70

R. P. N.


Action Results

(Rev.) 9X 11 06

Stop added, sprayer checked on line


5 175 Use Design of Experiments (DOE) on viscosity vs. temperature vs. pressure

Automate spraying

of 1

1450

Prepared By J. Ford - X6521 - Assy Ops


▲

Add positive 5 280 depth stop to sprayer

D e R. t P. e N. c

8

6

3

Page 1

FMEA Number

7

4

TABLE 5. PROCESS FMEA

▲

PROCESS FMEA INTRODUCTION (Continued) The Process FMEA is a living document and should be initiated: • Before or at the feasibility stage, • Prior to tooling for production, and • Take into account all manufacturing operations, from individual components to assemblies. Early review and analysis of new or revised processes is promoted to anticipate, resolve, or monitor potential process concerns during the manufacturing planning stages of a new model or component program. The Process FMEA assumes the product as designed will meet the design intent. Potential failure modes that can occur because of a design weakness may be included in a Process FMEA. Their effect and avoidance is covered by the Design FMEA. The Process FMEA does not rely on product design changes to overcome weaknesses in the process. However, it does take into consideration a product’s design characteristics relative to the planned manufacturing or assembly process to assure that, to the extent possible, the resultant product meets customer needs and expectations.

DEVELOPMENT OF A PROCESS FMEA The process-responsible engineer has at his or her disposal a number of documents that will be useful in preparing the Process FMEA. The FMEA begins by developing a list of what the process is expected to do and what it is expected not to do, i.e., the process intent. The Process FMEA should begin with a flow chart of the general process. This flow chart should identify the product/process characteristics associated with each operation. Identification of some product effects from the corresponding Design FMEA, should be included, if available. Copies of the flow chart used in FMEA preparation should accompany the FMEA. In order to facilitate documentation of the analysis of potential failures and their consequences, a Process FMEA form has been developed and is in Appendix G.

1)

FMEA Number

Enter the FMEA document number, which may be used for tracking. Note:

For an example of items 1-22 see Table 5.

– 37 –


5

2

11

10

12



▲



Requirements

9

Process Function




7

7


– 38 – 8

17

SAMPLE





16


9X 08 26 Job #1



8


14

O c c u r


▲

7

7

C S l e a v s s

16



▲



Item


18

19

70 None


5


Mfg Engrg 9X 10 01

Mfg Engrg 9X 12 15

MFG Engrg 9X 10 15

20


1

21

Actions Taken




7

7

7

1

1

2

7

5

5

49

35

70

R. P. N.


Action Results

(Rev.) 9X 11 06




Automate spraying

of 1

1450



▲


D e R. t P. e N. c

8

6

3

Page 1

FMEA Number

7

4


▲

PROCESS FMEA 2)

Item

Enter the name and number of the system, subsystem, or component for which the process is being analyzed.

3)

Process Responsibility

Enter the OEM, department, and group. Also include the supplier name if known.

4)

Prepared By

Enter the name, telephone number, and company of the engineer responsible for preparing the FMEA.

5)

Model Year(s)/Program(s)

Enter the intended model year(s)/program(s) that will use and/or be affected by the design/process being analyzed (if known).

6)

Key Date

Enter the initial FMEA due date, which should not exceed the scheduled start of production date. Note:

In the case of a supplier, the initial FMEA due date should not exceed the customer required Production Part Approval Process (PPAP) submission date.

7)

FMEA Date

Enter the date the original FMEA was compiled and the latest revision date.

8)

Core Team

List the names of the responsible individuals and departments that have the authority to identify and/or perform tasks. (It is recommended that each team member's name, department, telephone number, addresse, etc., be included on a distribution list.)

9)

Process Function/ Requirements

Enter a simple description of the process or operation being analyzed (e.g., turning, drilling, tapping, welding, assembling). In addition, it is recommended to record the associated process/operation number for the step being analyzed. The team should review applicable performance, material, process, environmental, and safety standards. Indicate as concisely as possible the purpose of the process or operation being analyzed, including information about the design (metrics/ measurables) of the system, subsystem, or component. Where the process involves numerous operations (e.g., assembling) with different potential modes of failure, it may be desirable to list the operations as separate elements.

10) Potential Failure Mode

Potential failure mode is defined as the manner in which the process could potentially fail to meet the process requirements and/or design intent as described in the process function/ requirements column. It is a description of the nonconformance at that specific operation. It can be a cause associated with a potential failure mode in a subsequent (downstream) operation or an effect associated with a potential failure in a previous (upstream) operation. However, in preparing the FMEA, assume that the incoming part(s)/material(s) are correct. Exceptions can be made by the FMEA team where historical data indicate deficiencies in incoming part quality. List each potential failure mode for the particular operation in terms of a component, subsystem, system, or process characteristic. Assume that the failure could occur but may not necessarily occur. The process engineer/team should be able to – 39 –


5

2

11

10

12



▲



Requirements

9

Process Function




7

7


– 40 – 8

17

SAMPLE





16


9X 08 26 Job #1



8


14

O c c u r


▲

7

7

C S l e a v s s

16



▲



Item


18

19

70 None


5


Mfg Engrg 9X 10 01

Mfg Engrg 9X 12 15

MFG Engrg 9X 10 15

20


1

21

Actions Taken




7

7

7

1

1

2

7

5

5

49

35

70

R. P. N.


Action Results

(Rev.) 9X 11 06




Automate spraying

of 1

1450



▲


D e R. t P. e N. c

8

6

3

Page 1

FMEA Number

7

4


▲

PROCESS FMEA 10) Potential Failure Mode (continued)

pose and answer the following questions: • •

How can the process/part fail to meet requirements? Regardless of engineering specifications, what would a customer (end user, subsequent operations, or service) consider objectionable? Start by comparing similar processes and reviewing customer (end user and subsequent operation) claims relating to similar components. In addition, a knowledge of the design intent is necessary. Typical failure modes could be but are not limited to: Bent Burred Hole off-location Cracked Hole too shallow Hole missing Handling damage Dirty Hole too deep Surface too rough Deformed Surface too smooth Open circuited Short circuited Mis-labeled NOTE:

11) Potential Effect(s) of Failure

Potential failure modes should be described in "physical" or technical terms, not as a symptom noticeable by the customer.

Potential effects of failure are defined as the effects of the failure mode on the customer(s). Describe the effects of the failure in terms of what the customer might notice or experience, remembering that the customer may be an internal customer as well as the ultimate end user. State clearly if the failure mode could impact safety or cause noncompliance to regulations. The customer(s) in this context could be the next operation, subsequent operations or locations, the dealer, and/or the vehicle owner. Each must be considered when assessing the potential effect of a failure. For the end user, the effects should always be stated in terms of product or system performance, such as: Noise Erratic operation Effort Unpleasant odor Operation impaired Intermittent operation Leaks Rework/Repairs Scrap

Rough Excessive Inoperative Unstable Draft Poor appearance Vehicle control impaired Customer dissatisfaction

If the customer is the next operation or subsequent operation(s)/ location(s), the effects should be stated in terms of process/ operation performance, such as: Cannot fasten Cannot bore/tap Cannot mount Cannot face Damages equipment

12) Severity (S)

Does not fit Does not connect Does not match Causes excessive tool wear Endangers operator

Severity is the rank associated with the most serious effect for a given failure mode. Severity is a relative ranking within the – 41 –


5

2

11

10

12



▲



Requirements

9

Process Function




7

7


– 42 – 8

17

SAMPLE





16


9X 08 26 Job #1



8


14

O c c u r


▲

7

7

C S l e a v s s

16



▲



Item


18

19

70 None


5


Mfg Engrg 9X 10 01

Mfg Engrg 9X 12 15

MFG Engrg 9X 10 15

20


1

21

Actions Taken




7

7

7

1

1

2

7

5

5

49

35

70

R. P. N.


Action Results

(Rev.) 9X 11 06




Automate spraying

of 1

1450



▲


D e R. t P. e N. c

8

6

3

Page 1

FMEA Number

7

4


▲

PROCESS FMEA Table 6. Suggested PFMEA Severity Evaluation Criteria Criteria: Severity of Effect 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)

Criteria: Severity of Effect 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. (Manufacturing/ Assembly Effect) Ranking

Very high severity ranking when a potential failure mode affects safe vehicle operation and/or involves noncompliance with government regulation without warning.

Or may endanger operator (machine or assembly) without warning.

10

Very high severity ranking when a Hazardous with warning potential failure mode affects safe vehicle operation and/or involves noncompliance with government regulation with warning.

Or may endanger operator (machine or assembly) with warning.

9

Very High

Vehicle/item inoperable (loss of primary function).

Or 100% of product may have to be scrapped, or vehicle/item repaired in repair department with a repair time greater than one hour.

8

High

Vehicle/Item operable but at a reduced level of performance. Customer very dissatisfied.

Or product may have to be sorted and a portion (less than 100%) scrapped, or vehicle/item repaired in repair department with a repair time between a half-hour and an hour.

7

Moderate

Vehicle/Item operable but Comfort/ Convenience item(s) inoperable. Customer dissatisfied.

Or a portion (less than 100%) of the product may have to scrapped with no sorting, or vehicle/item repaired in repair department with a repair time less than a half-hour.

6

Low

Vehicle/Item operable but Comfort/ Convenience item(s) operable at a reduced level of performance.

Or 100% of product may have to be reworked, or vehicle/item repaired offline but does not go to repair department.

5

Very Low

Fit and Finish/Squeak and Rattle item does not conform. Defect noticed by most customers (greater than 75%).

Or the product may have to be sorted, with no scrap, and a portion (less than 100%) reworked.

4

Minor

Fit and Finish/Squeak and Rattle item does not conform. Defect noticed by 50% of customers.

Or a portion (less than 100%) of the product may have to be reworked, with no scrap, on-line but out-of-station.

3

Very Minor

Fit and Finish/Squeak and Rattle item does not conform. Defect noticed by discriminating customers (less than 25%). No discernible effect.

Or a portion (less than 100%) of the product may have to be reworked, with no scrap, on-line but in-station.

2

Effect Hazardous without warning

None

– 43 –

Or slight inconvenience to operation or operator, or no effect.

1


5

2

11

10

12



▲



Requirements

9

Process Function




7

7


– 44 – 8

17

SAMPLE





16


9X 08 26 Job #1



8


14

O c c u r


▲

7

7

C S l e a v s s

16



▲



Item


18

19

70 None


5


Mfg Engrg 9X 10 01

Mfg Engrg 9X 12 15

MFG Engrg 9X 10 15

20


1

21

Actions Taken




7

7

7

1

1

2

7

5

5

49

35

70

R. P. N.


Action Results

(Rev.) 9X 11 06




Automate spraying

of 1

1450



▲


D e R. t P. e N. c

8

6

3

Page 1

FMEA Number

7

4


▲

12) Severity (S) (continued)

scope of the individual FMEA. A reduction in severity ranking index can be effected through a design change to system, subsystem or component, or a redesign of the process. If the customer affected by a failure mode is the manufacturing or assembly plant or the product user, assessing the severity may lie outside the immediate process engineer’s/team’s field of experience or knowledge. In these cases, the Design FMEA, design engineer, and/or subsequent manufacturing or assembly plant process engineer, should be consulted. Suggested Evaluation Criteria The team should agree on an evaluation criteria and ranking system, that is consistent, even if modified for individual process analysis. (See Table 6) Severity should be estimated using Table 6 as a guideline: NOTE:

13) Classification

It is not recommended to modify criteria for ranking values of 9 and 10. Failure modes with a rank of severity 1 should not be analyzed further.

This column may be used to classify any special product or process characteristics (e.g., critical, key, major, significant) for components, subsystems, or systems that may require additional process controls. This column may also be used to highlight high priority failure modes for engineering assessment. If a classification is identified in the Process FMEA, notify the design responsible engineer since this may affect the engineering documents concerning control item identification. Special product or process characteristic symbols and their usage is directed by specific company policy and is not standardized in this document.

14) Potential Cause(s)/ Mechanism(s) of Failure

Potential cause of failure is defined as how the failure could occur, described in terms of something that can be corrected or can be controlled. List, to the extent possible, every failure cause assignable to each potential failure mode. If a cause is exclusive to the failure mode, i.e., if correcting the cause has a direct impact on the failure mode, then this portion of the FMEA thought process is completed. Many causes, however, are not mutually exclusive, and to correct or control the cause, a design of experiments, for example, may be considered to determine which root causes are the major contributors and which can be most easily controlled. The causes should be described so that remedial efforts can be aimed at those causes which are pertinent. Typical failure causes may include, but are not limited to: Improper torque - over, under Improper weld - current, time, pressure Inaccurate gauging Improper heat treat - time, temperature

– 45 –


5

2

11

10

12



▲



Requirements

9

Process Function




7

7


– 46 – 8

17

SAMPLE





16


9X 08 26 Job #1



8


14

O c c u r


▲

7

7

C S l e a v s s

16



▲



Item


18

19

70 None


5


Mfg Engrg 9X 10 01

Mfg Engrg 9X 12 15

MFG Engrg 9X 10 15

20


1

21

Actions Taken




7

7

7

1

1

2

7

5

5

49

35

70

R. P. N.


Action Results

(Rev.) 9X 11 06




Automate spraying

of 1

1450



▲


D e R. t P. e N. c

8

6

3

Page 1

FMEA Number

7

4


▲

PROCESS FMEA 14) Potential Cause(s)/ Mechanism(s) of Failure (continued)

Inadequate gating/venting Inadequate or no lubrication Part missing or mislocated Worn locator Worn tool Chip on locator Broken tool Improper machine setup Improper programming Only specific errors or malfunctions (e.g., operator fails to install seal) should be listed; ambiguous phrases (e.g., operator error, machine malfunction) should not be used.

15) Occurrence (O)

Occurrence is the likelihood that a specific cause/mechanism of failure will occur. The likelihood of occurrence ranking number has a relative meaning rather than an absolute value. Preventing or controlling the causes/mechanisms of failure through a design or process change is the only way a reduction in the occurrence ranking can be effected. Estimate the likelihood of occurrence of potential failure cause/ mechanism on a 1 to 10 scale. A consistent occurrence ranking system should be used to ensure continuity. The occurrence ranking number is a relative rating within the scope of the FMEA and may not reflect the actual likelihood of occurrence. The “Possible Failure Rates” are based on the number of failures that are anticipated during the process execution. If statistical data are available from a similar process, the data should be used to determine the occurrence ranking. In all other cases, a subjective assessment can be made by using the word descriptions in the left column of the table, along with any historical data available for similar processes. Suggested Evaluation Criteria The team should agree on an evaluation criteria and ranking system that is consistent, even if modified for individual process analysis. (See Table 7) Occurrence should be estimated using Table 7 as a guideline: NOTE:

The ranking value of 1 is reserved for failure is Unlikely”.

– 47 –

“Remote:


5

2

11

10

12



▲



Requirements

9

Process Function




7

7


– 48 – 8

17

SAMPLE





16


9X 08 26 Job #1



8


14

O c c u r


▲

7

7

C S l e a v s s

16



▲



Item


18

19

70 None


5


Mfg Engrg 9X 10 01

Mfg Engrg 9X 12 15

MFG Engrg 9X 10 15

20


1

21

Actions Taken




7

7

7

1

1

2

7

5

5

49

35

70

R. P. N.


Action Results

(Rev.) 9X 11 06




Automate spraying

of 1

1450



▲


D e R. t P. e N. c

8

6

3

Page 1

FMEA Number

7

4


▲

PROCESS FMEA Table 7. Suggested PFMEA Occurrence Evaluation Criteria Likely Failure Rates*

Ranking

> 100 per thousand pieces

10

50 per thousand pieces

9


8


7


6


5


4

0.5 per thousand pieces

3


2

< 0.01 per thousand pieces

1

Probability Very High: Persistent Failures

High: Frequent Failures

Moderate: Occasional Failures

Low: Relatively Few Failures

Remote: Failure is Unlikely

*For associated Ppk calculations and values, see Appendix I.

16) Current Process Controls

Current Process Controls are descriptions of the controls that either prevent to the extent possible the failure mode or cause/ mechanism of failure from occurring, or detect the failure mode or cause/mechanism of failure should it occur. These controls can be process controls such as error/mistake proofing, statistical process control (SPC), or can be post-process evaluation. The evaluation may occur at the subject operation or at subsequent operations. There are two types of Process Controls to consider: Prevention:

Detection:

Prevent the cause/mechanism of failure or the failure mode from occurring, or reduce their rate or occurrence, Detect the cause/mechanism of failure or the failure mode, and lead to corrective action(s).

The preferred approach is to first use prevention controls, if possible. The initial occurrence rankings will be affected by the prevention controls provided they are integrated as part of the process intent. The initial rankings for detection will be based on process controls that either detect the cause/mechanism of failure, or detect the failure mode. The Process FMEA form in this manual has two columns for the process controls (i.e., separate columns for Prevention Controls and Detection Controls) to assist the team in clearly distinguishing between these two types of process controls. This allows for a quick visual determination that both types of process controls have been considered. Use of this twocolumn form is the preferred approach. – 49 –


5

2

11

10

12



▲



Requirements

9

Process Function




7

7


– 50 – 8

17

SAMPLE





16


9X 08 26 Job #1



8


14

O c c u r


▲

7

7

C S l e a v s s

16



▲



Item


18

19

70 None


5


Mfg Engrg 9X 10 01

Mfg Engrg 9X 12 15

MFG Engrg 9X 10 15

20


1

21

Actions Taken




7

7

7

1

1

2

7

5

5

49

35

70

R. P. N.


Action Results

(Rev.) 9X 11 06




Automate spraying

of 1

1450



▲


D e R. t P. e N. c

8

6

3

Page 1

FMEA Number

7

4


▲

PROCESS FMEA 16) Current Process Controls (continued)

If a one-column (for process controls) form is used, then the following prefixes should be used. For prevention controls, place a 'P' before each prevention control listed. For detection controls, place a 'D' before each detection control listed. Once the process controls have been identified, review all prevention controls to determine if any occurrence rankings need to be revised.

17) Detection (D)

Detection is the rank associated with the best detection control listed in the process control column. Detection is a relative ranking, within the scope of the individual FMEA. In order to achieve a lower ranking, generally the planned process control has to be improved. Assume the failure has occurred and then assess the capabilities of all "Current Process Controls" to prevent shipment of the part having this failure mode or defect. Do not automatically presume that the detection ranking is low because the occurrence is low (e.g., when control charts are used), but do assess the ability of the process controls to detect low frequency failure modes or prevent them from going further in the process. 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.

– 51 –


5

2

11

10

12



▲



Requirements

9

Process Function




7

7


– 52 – 8

17

SAMPLE





16


9X 08 26 Job #1



8


14

O c c u r


▲

7

7

C S l e a v s s

16



▲



Item


18

19

70 None


5


Mfg Engrg 9X 10 01

Mfg Engrg 9X 12 15

MFG Engrg 9X 10 15

20


1

21

Actions Taken




7

7

7

1

1

2

7

5

5

49

35

70

R. P. N.


Action Results

(Rev.) 9X 11 06




Automate spraying

of 1

1450



▲


D e R. t P. e N. c

8

6

3

Page 1

FMEA Number

7

4


▲

PROCESS FMEA 17) Detection (D) (continued)

Suggested Evaluation Criteria The team should agree on an evaluation criteria and ranking system that is consistent, even if modified for individual product analysis. (See Table 8.) Detection should be estimated using Table 8 as a guideline. NOTE:

The ranking value of 1 is reserved for “Certain to Detect.

TABLE 8. Suggested PFMEA Detection Evaluation Criteria Detection

Criteria

Almost Impossible Very Remote Remote

Low

Absolute certainty of nondetection. Controls will probably not detect. Controls have poor chance of detection. Controls have poor chance of detection. Controls may detect.

X

Moderate

Controls may detect.

X

Very Low

Inspection Types A B C

Cannot detect or is not checked.

10

X

Control is achieved with indirect or random checks only. Control is achieved with visual inspection only.

9

Control is achieved with double visual inspection only. Control is achieved with charting methods, such as SPC {Statistical Process Control}. Control is based on variable gauging after parts have left the station, or Go/No Go gauging performed on 100% of the parts after parts have left the station. Error detection in subsequent operations, OR gauging performed on setup and first-piece check (for set-up causes only). Error detection in-station, or error detection in subsequent operations by multiple layers of acceptance: supply, select, install, verify. Cannot accept discrepant part. Error detection in-station (automatic gauging with automatic stop feature). Cannot pass discrepant part. Discrepant parts cannot be made because item has been error-proofed by process/product design.

7

X

X

X

High

Controls have a good chance to detect.

X

X

Very High

Controls almost certain to detect.

X

X

Very High

Controls certain to detect.

X

Ranking

X

X

Moderately Controls have a good High chance to detect.

Suggested Range of Detection Methods

X

8

6 5

4

3

2

1

Inspection Types: A. Error-proofed B. Gauging C. Manual Inspection

18) Risk Priority Number (RPN) The risk priority number is the product of the severity (S), occurrence (O), and detection (D) rankings. (S) x (O) x (D) = RPN Within the scope of the individual FMEA, this value (between 1 and 1000) can be used to rank order the concerns in the process.

– 53 –


5

2

11

10

12



▲



Requirements

9

Process Function




7

7


– 54 – 8

17

SAMPLE





16


9X 08 26 Job #1



8


14

O c c u r


▲

7

7

C S l e a v s s

16



▲



Item


18

19

70 None


5


Mfg Engrg 9X 10 01

Mfg Engrg 9X 12 15

MFG Engrg 9X 10 15

20


1

21

Actions Taken




7

7

7

1

1

2

7

5

5

49

35

70

R. P. N.


Action Results

(Rev.) 9X 11 06




Automate spraying

of 1

1450



▲


D e R. t P. e N. c

8

6

3

Page 1

FMEA Number

7

4


▲

PROCESS FMEA 19) Recommended Action(s)

Engineering assessment for preventive/corrective action should be first directed at high severity, high RPN, and other items designated by the team. The intent of any recommended action is to reduce rankings in the following order: severity, occurrence, and detection. In general practice, when the severity is 9 or 10, special attention must be given to ensure that the risk is addressed through existing design actions/controls or process preventive/corrective action(s), regardless of the RPN. In all cases where the effect of an identified potential failure mode could be a hazard to manufacturing/assembly personnel, preventive/corrective actions should be taken to avoid the failure mode by eliminating or controlling the cause(s), or appropriate operator protection should be specified. After special attention has been given to severity rankings of 9 or 10, the team then addresses other failure modes, with the intent of reducing severity, then occurrence, and then detection. Actions such as, but not limited to, the following should be considered: •

To reduce the probability of occurrence, process and/or design revisions are required. An action-oriented study of the process using statistical methods could be implemented with an ongoing feedback of information to the appropriate operations for continuous improvement and defect prevention.

•

Only a design and/or process revision can bring about a reduction in the severity ranking.

•

The preferred method to accomplish a reduction in the detection ranking is the use of error/mistake proofing methods. Generally, improving detection controls is costly and ineffective for quality improvements. Increasing the frequency of quality controls inspection is not an effective preventive/corrective action and should only be used as a temporary measure since permanent preventive/corrective action is required. In some cases, a design change to a specific part may be required to assist in the detection. Changes to the current control system may be implemented to increase this probability. Emphasis must, however, be placed on preventing defects (i.e., reducing the occurrence) rather than detecting them. An example would be the use of statistical process control and process improvement rather than random quality checks or associated inspection.

If engineering assessment leads to no recommended actions for a specific failure mode/cause/control combination, indicate this by entering “None” in this column.

– 55 –


5

2

11

10

12



▲



Requirements

9

Process Function




7

7


– 56 – 8

17

SAMPLE





16


9X 08 26 Job #1



8


14

O c c u r


▲

7

7

C S l e a v s s

16



▲



Item


18

19

70 None


5


Mfg Engrg 9X 10 01

Mfg Engrg 9X 12 15

MFG Engrg 9X 10 15

20


1

21

Actions Taken




7

7

7

1

1

2

7

5

5

49

35

70

R. P. N.


Action Results

(Rev.) 9X 11 06




Automate spraying

of 1

1450



▲


D e R. t P. e N. c

8

6

3

Page 1

FMEA Number

7

4


▲

PROCESS FMEA 20) Responsibility for the Recommended Action(s)

Enter the individual responsible for the recommended action, and the target completion date.

21) Action(s) Taken

After the action has been implemented, enter a brief description of the actual action and effective date.

22) Action Results

After the preventive/corrective action has been identified, estimate and record the resulting severity, occurrence, and detection rankings. Calculate and record the resulting RPN. If no actions are taken, leave the related ranking columns blank. All revised ratings should be reviewed and if further action is considered necessary, repeat the analysis. The focus should always be on continuous improvement.

Follow-Up Actions The process-responsible engineer is responsible for ensuring that all actions recommended have been implemented or adequately addressed. The FMEA is a living document and should always reflect the latest design level as well as the latest relevant actions, including those occurring after the start of production. The process-responsible engineer has several means of ensuring that concerns are identified and that recommended actions are implemented. They include, but are not limited to the following: • Ensuring that process/product requirements are achieved, • Reviewing engineering drawings, process/product specifications, and process flow, • Confirming the incorporation of changes in assembly/ manufacturing documentation and, • Reviewing Control Plans and operation instructions.

– 57 –

PROCESS FMEA

– 58 –

APPENDIX A DESIGN FMEA QUALITY OBJECTIVES Note: Specific Program Requirements take precedence

1. DESIGN IMPROVEMENTS

The FMEA drives Design Improvements as the primary objective.

2. HIGH RISK FAILURE MODES The FMEA addresses all high risk Failure Modes, as identified by the FMEA team, with executable Action Plans. All other failure modes are considered.

3. A/D/V OR DVP & R PLANS

The Analysis/Development/Validation (A/D/V), and/or Design Verification Plan and Report (DVP&R) considers the failure modes from the FMEA.

4. INTERFACES

The FMEA scope includes integration and interface failure modes in both block diagram and analysis.

5. LESSONS LEARNED

The FMEA considers all major “lessons learned” (such as high warranty, campaigns, etc.) as input to failure mode identification.

6. SPECIAL OR KEY CHARACTERISTICS

The FMEA identifies appropriate Key Characteristics candidates as input to the Key Characteristics selection process, if applicable due to company policy.

7. TIMING

The FMEA is completed during the “Window of Opportunity” where it could most efficiently impact the product design.

8. TEAM

The right people participate as part of the FMEA team throughout the analysis, and are adequately trained in FMEA methods. As appropriate, a facilitator should be used.

9. DOCUMENTATION

The FMEA document is completely filled out "by the book", including "Action Taken" and new RPN values.

10. TIME USAGE

Time spent by the FMEA team as early as possible is an effective and efficient use of time, with a value-added result. This assumes Recommended Actions are identified as required and the actions are implemented.

– 59 –

APPENDIX B PROCESS FMEA QUALITY OBJECTIVES Note: Specific Program Requirements take precedence.

1. PROCESS IMPROVEMENTS The FMEA drives Process Improvements as the primary objective, with an emphasis on Error/Mistake Proofing solutions.

2. HIGH RISK FAILURE MODES The FMEA addresses all high risk Failure Modes, as identified by the FMEA team, with executable Action Plans. All other failure modes are considered.

3. CONTROL PLANS

The Pre-launch and Production Control Plans consider the failure modes from the Process FMEA.

4. INTEGRATION

The FMEA is integrated and consistent with the Process Flow Diagram and the Process Control Plan. The Process FMEA considers the Design FMEA, if available as part of its analysis.

5. LESSONS LEARNED

The FMEA considers all major “lessons learned” (such as high warranty, campaigns, non-conforming product, customer complaints, etc.) as input to failure mode identification.

6. SPECIAL OR KEY CHARACTERISTICS

The FMEA identifies appropriate Key Characteristics candidates as input to the Key Characteristics selection process, if applicable due to company policy.

7. TIMING

The FMEA is completed during the “Window of Opportunity” where it could most efficiently impact the design of product or process.

8. TEAM

The right people participate as part of the FMEA team throughout the analysis, and are adequately trained in FMEA methods. As appropriate, a facilitator should be used.

9. DOCUMENTATION

The FMEA document is completely filled out "by the book", including "Action Taken" and new RPN values.

10. TIME USAGE

Time spent by the FMEA team as early as possible is an effective and efficient use of time, with a value-added result. This assumes Recommended Actions are identified as required and the actions are implemented.

– 60 –

APPENDIX C DESIGN FMEA BLOCK DIAGRAM EXAMPLE

FAILURE MODE AND EFFECTS ANALYSIS (FMEA) BLOCK DIAGRAM/ENVIRONMENTAL EXTREMES SYSTEM NAME: YEAR VEHICLE PLATFORM: FMEA I.D. NUMBER

FLASHLIGHT 1994 NEW PRODUCT XXXI10D001

OPERATIONAL ENVIRONMENTAL EXTREMES

TEMPERATURE: -20 TO 160 F CORROSIVE: TEST SCHEDULE B SHOCK: 6 FOOT DROP FOREIGN MATERIAL: DUST FLAMMABILITY: (WHAT COMPONENT(S) ARE NEAR HEAT SOURCE(S)? OTHER:

LETTERS = COMPONENTS NUMBERS = ATTACHING METHODS

= ATTACHED/JOINED

VIBRATION: NOT APPLICABLE HUMIDITY: 0 - 100 % RH

------- = INTERFACING, NOT JOINED

= NOT INCLUDED IN THIS FMEA

The example below is a relational block diagram. Other types of block diagrams may be used by the FMEA Team to clarify the item(s) being considered in their analysis

SWITCH ON/OFF C 2

BULB ASSEMBLY D

3

HOUSING A

4

4 1

PLATE E +

5

BATTERIES B

COMPONENTS A. HOUSING B. BATTERIES (2 D CELL) C. ON/OFF SWITCH D. BULB ASSEMBLY E. PLATE F. SPRING

5

SPRING F -

ATTACHING METHOD 1. SKIP FIT 2. RIVETS 3. THREAD 4. SNAP FIT 5. COMPRESSIVE FIT

– 61 –

Key Date _________

Model Year(S)/Vehicle(s) _____________________

Item

Function



C S l e a v s s Potential Cause(s)/ Mechanism(s) of Failure

O c c u r

Core Team ___________________________________________________________________________________________

Design Responsibility _________

Current Design Controls - Prevention - Detection


____ Component ___

____ Subsystem

____ System

D e R. t P. e N. c

of

Recommended Action(s) Responsibility & Target Completion Date

FMEA Date (Orig.) _________

Prepared By

Page

FMEA Number

Actions Taken

S O D e c e v c t

Action Results

(Rev.)

R. P. N.

APPENDIX D

STANDARD FORM FOR DESIGN FMEA

– 62 –

Item

Function

Core Team


MODEL YEARS(S)/Vehicle(s)

Component

Subsystem

System


C S l e a v s s Potential Cause(s)/ Mechanism(s) of Failure

Key Date

O c c u r

Design Responsibility




D e R. t P. e N. c Recommended Action(s)

of


FMEA Date (Orig.)

Prepared By

Page

FMEA Number

Actions Taken

S O D e c e v c t

Action Results

(Rev.)

R. P. N.

APPENDIX D

STANDARD FORM FOR DESIGN FMEA

– 63 –


Subsystem

5

2

Function

9

– 64 –



12 C S l e a v s s

7

7

7


11


▲


10


O c c u r

17

18

19


20


4

SAMPLE




None


28



2




D e R. t P. e N. c




16


1

21



7

7


7

1

1

2

2

1

3

2

2

7

21

28

28

R. P. N.



8

(Rev.) 8X 07 14




16


of 1

1234


Page 1

FMEA Number


4

15

6

3

▲




14


13




▲


Item

▲



X


▲

System

7

4

APPENDIX E

DESIGN FMEA EXAMPLE

Appendix F System FMEA To help illustrate the meaning of System, Subsystem, and Component FMEA’s, two examples have been constructed below in Figure F1 (for Interfaces and Interactions) and in Figure F2 (for Item, Function, and Failure Modes). EXAMPLE 1: Interfaces and Interactions

Subsystem B

Subsystem A

Subsystem C

System Subsystem D

Environment

Figure F1. Interfaces and Interactions The FMEA team is responsible for specifying the scope of its respective FMEA’s. The example in Figure F1 shows that the team has specified Subsystems A, B, C, and D along with the surrounding environment as comprising the System that must be considered while completing the System FMEA. INTERFACES:

SUBSYSTEMS ARE DIRECTLY CONNECTED VIA INTERFACES. In Figure F1, interfaces between subsystems are shown where Subsystem A touches (connects with) Subsystem B, B touches C, C touches D, A touches D, and B touches D. The Environment also touches each of the subsystems listed in Figure F1, which requires that the ‘Environmental Interfaces’ be considered when completing the FMEA. NOTE: Each Subsystem FMEA should have its Interfaces included in its respective Subsystem FMEA.

INTERACTIONS:

A CHANGE IN ONE SUBSYSTEM MIGHT CAUSE A CHANGE IN ANOTHER SUBSYSTEM. In Figure F1, interactions between subsystems can occur among any of the interfacing systems (e.g., Subsystem A heats up, resulting in Subsystem D and Subsystem B also gaining heat through the respective interfaces, as well as Subsystem A giving off heat to the environment). Interactions might also occur among ‘non-contacting’ systems via transfer through the ‘environment’ (e.g., if the environment is composed of high humidity and Subsystems A and C are dissimilar metals separated by a non-metal composing Subsystem B, Subsystems A and C can still have an electrolytic reaction due to the moisture from the environment). Thus, interactions among non-contacting subsystems can be relatively difficult to predict but are important and should be considered.

– 65 –

EXAMPLE 2: Items, Functions, and Failure Modes Figure F2 (see next page) describes a method of showing the Items, Functions, and Failure Modes in a ‘tree arrangement’ that can assist the team in visualizing the System, Subsystems, and Components. At the System Level, the descriptions will tend to be much more general than for the Subsystems and Components (Components will usually have the most specific descriptions). The ‘tree arrangement’ is arranged as follows for the System, Subsystem, and Components: ITEM Design Objectives (a statement of design objectives is often helpful)

- FUNCTION 1 POTENTIAL FAILURE MODE A POTENTIAL FAILURE MODE B etc.....

- FUNCTION 2 POTENTIAL FAILURE MODE A POTENTIAL FAILURE MODE B etc..... - etc.....

– 66 –

– 67 –

Potential Failure Mode(s): • seating position is not comfortable

Function: – provide comfortable transportation

Potential Failure Mode(s): • chain breaks frequently • Tires require frequent maintenance

Function: – provide reliable transportation

Potential Failure Mode(s): • difficult to steer • difficult to pedal

Function: – ease of use

Design Objectives: 1) minimum 3000 hours of riding without need for maintenance and 10,000 hours of riding for design life. 2) accommodates male adults comfortably to the 99.5th percentile 3) ... etc. ...

Bicycle

System Level

Figure F2. Items, Functions, and Failures

Chain Assembly

Seat Assembly

Sprocket Assembly

Rear Wheel Assembly

Front Wheel Assembly

Handle Bar Assembly

Potential Failure Mode(s): • finish (shine) deteriorates • paint chips

Function: – provides pleasing appearance

Potential Failure Mode(s): • structural failure of seat support • excessive deflection of seat support

Function: – provides stable attachment for seat support

Frame

Subsystem Level

Sprocket Tube

Lower Rear Tube

Lower Front Tube

Potential Failure Mode(s):

Function: – support frame assembly production methods (welding)

Potential Failure Mode(s): • length of frame mounting points too long • length of frame mounting points too short

Function: – provides dimensional control for correct finished frame geometry

Potential Failure Mode(s): • structural failure • excessive deflection

Function: – provides structural support

Upper Frame

Component Level

Key Date _________

Process Responsibility __________

of

FMEA Date (Orig.) _________

Prepared By

Page

FMEA Number

(Rev.)

Requirements

Process Function



C S l e a v s s

Potential Cause(s)/ Mechanism(s) of Failure O c c u r Current Design Controls - Prevention - Detection

D e R. t P. e N. c Recommended Action(s) Responsibility & Target Completion Date Actions Taken

S O D e c e v c t

Action Results R. P. N.

Core Team _____________________________________________________________________________________________________________________________________________________________________________

Model Year(S)/Vehicle(s) ____________________________

Item


APPENDIX G

STANDARD FORM FOR PROCESS FMEA

– 68 –

Requirements

Process Function



C S l e a v s s

Potential Cause(s)/ Mechanism(s) of Failure O c c u r

Key Date

Model Years(S)/Vehicle(s)

Core Team

Process Responsibility

Item

Current Process Controls Prevention Current Process Controls Detection


D e R. t P. e N. c Recommended Action(s)

of


FMEA Date (Orig.)

Prepared By

Page

FMEA Number

Actions Taken

S O D e c e v c t

Action Results

(Rev.)

R. P. N.

APPENDIX G

STANDARD FORM FOR PROCESS FMEA

– 69 –


5

2

11

10

12



▲



Requirements

9

Process Function




7

7


– 70 – 8

17

SAMPLE





16


9X 08 26 Job #1



8


14

O c c u r


▲

7

7

C S l e a v s s

16



▲



Item


18

19

70 None


5


Mfg Engrg 9X 10 01

Mfg Engrg 9X 12 15

MFG Engrg 9X 10 15

20


1

21

Actions Taken




7

7

7

1

1

2

7

5

5

49

35

70

R. P. N.


Action Results

(Rev.) 9X 11 06




Automate spraying

of 1

1450



▲


D e R. t P. e N. c

8

6

3

Page 1

FMEA Number

7

4

APPENDIX H

PROCESS FMEA EXAMPLE

▲

APPENDIX I SUGGESTED PFMEA OCCURRENCE EVALUATION CRITERIA WITH Ppk VALUES Probability Very High: Persistent Failures

High: Frequent Failures

Moderate: Occasional Failures

Low: Relatively Few Failures

Remote: Failure is Unlikely

Likely Failure Rates*

Ppk

Ranking

> 100 per thousand pieces

< 0.55

10


≥ 0.55

9


≥ 0.78

8


≥ 0.86

7


≥ 0.94

6


≥ 1.00

5


≥ 1.10

4


≥ 1.20

3


≥ 1.30

2

< 0.01 per thousand pieces

≥ 1.67

1

Sample Calculation Sample Calculation to determine Ppk value from a likely failure rate of 5 per thousand pieces.

Defect rate = 0.05 2

5 = 1000

0.05 .

= 0.0025 divided by 2 for out-of-specifications high or low.

Using a "Z" table the associated "Z" value is 2.81 for a tail value of 0.0025. 1. Z =

SL - x σˆ s

where: x = Average SL = Specifications 2. Ppk =

min (SL upper - x, x - SL lower) 3σˆ s

3. Replace using Z 4. Ppk =

Note:

Z 2.81 = = 0.9367 ~ = 0.94 3 3

The above Ppk values are to be used by the FMEA team as guidance to assist in determining an occurrence ranking when valid statistical data is available. No other use of the above Ppk values is intended.

– 71 –

Glossary Control Plans

The control plan provides the process monitoring and control methods that will be used to control characteristics.

Design Intent

List of what a given component/subsystem/system is expected to do or not do.

Design Life

The time period (e.g., cycles, time, mileage) for which the design is intended to perform its requirements.

Design Validation/Verification (DV)

A program intended to ensure that the design meets its requirements.

Design of Experiments (DOE)

Methods that identify factors that affect the mean and variation with minimum testing/experimentation.

Error/Mistake Proofing

Each OEM may have its own unique definition for Error/Mistake Proofing. Confer with the OEM for the appropriate definition.

Feature

A measurable product characteristic (e.g., radius, hardness) or a measurable process characteristic (e.g., insertion force, temperature).

Pareto

A simple tool that can assist problem solving that involves ranking all potential problem areas.

Process

The combination of people, machines and equipment, raw materials, methods, and environment that produces a given product or service.

Process Change

A change in processing concept that could alter the capability of the process to meet the design requirements or the durability of the product.

Quality Function Deployment (QFD)

A structured method in which customer requirements are translated into appropriate technical requirements for each stage of product development and production.

Root Cause

The root cause is the reason for the primary non-conformance and is the item that requires change to achieve permanent preventive/corrective action.

Special Process Characteristic

A special process characteristic (e.g., critical, key, major, significant) is a process characteristic for which variation must be controlled to some target value to ensure that variation in a process or a special product characteristic is maintained to its target value during manufacturing and assembly.

Special Product Characteristic

A special product characteristic (e.g., critical, key, major, significant) is a product characteristic for which reasonably anticipated variation could significantly affect a product’s safety or compliance with governmental standards or regulations, or is likely to significantly affect customer satisfaction with a product.

Vehicle Campaign

Recall of vehicles for rework or safety inspection.

– 72 –

– 73 –

– 74 –

Inside Back Cover

Back Cover

FMEA Handbook

Recommend Documents