Change Record

DFMEA MANUAL

Document DEM102

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TABLE OF CONTENTS

SECTION / DESCRIPTION / PAGE

Title Page...... 1

Change Record...... 2

Table of Contents...... 3

1.introduction......

1.1Purpose......

1.2Referenced Documents......

2.Completing The Header (See CIRCLED Numbers 1-5)......

3.Completing The Footer (See CIRCLED Numbers 6-8)......

4.Functions (See CIRCLED Number 9)......

5.Items (See CIRCLED Number 10)......

6.Potential Failure Modes (See CIRCLED Number 11)......

7.Potential Failure Effects (See CIRCLED Number 12)......

8.Severity Criteria (See CIRCLED Number 13)......

9.Classification (See CIRCLED Number 14)......

10.Potential Causes (See CIRCLED Number 15)......

11.Occurrence (See CIRCLED Number 16)......

12.Current Design Controls (See CIRCLED Number 17)......

13.Detection (See CIRCLED Number 18)......

14.Risk Priority Number (RPN) (See CIRCLED Number 19)......

15.Recommended Action(s) (See CIRCLED Number 20)......

16.Responsibility (For Recommended Actions) (See CIRCLED # 21)......

17.Actions Taken (See CIRCLED Number 22)......

18.Resulting RPN (See CIRCLED Number 23)......

19.Follow-up......

DFMEA MANUAL

FOR COMPANY X AUTOMOTIVE SAFETY PRODUCTS

1.introduction

1.1Purpose

a)“In its most rigorous form, a FMEA is a summary of an engineer’s and the team’s thoughts (including an analysis of items that could go wrong based on experience and past concerns) 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.” (from the Introduction of the AIAG FMEA Manual). As indicated in the quotation from the AIAG manual above, a DFMEA is a tool intended to help an engineer quantify and organize design issues identified during the normal course of the design process. The objective of a FMEA is to provide an “impartial” analysis of the design process so that the most “critical” design issues are addressed first, and the least critical last. Properly applied, this technique should increase the efficiency of the design process. The generic FMEA process defined in the AIAG Manual may work well for traditional automotive items, such as springs and bumpers, where there is an extensive design and experience base. However, it is not intuitively obvious how to apply such a technique to unique, one-shot, high-reliability safety devices such as airbag inflators. The purpose of this document is to clarify the AIAG manual’s guidelines and provide examples of how the technique can and should be efficiently used at COMPANY X to aid the design process. The FMEA discipline requires a Design FMEA for all new parts, changed parts, and carryover parts used in new applications or environments. It should be initiated by an engineer from the design-responsible team, but should directly and actively involve representatives from all affected areas of COMPANY X.

b)Effective use of this tool requires a commitment to the technique, as well as a thorough understanding of the functional operation of the design being analyzed. The result of the DFMEA will be directly proportional to the quality of the technical input included in the analysis. Every new DFMEA should be a stand-alone document and should not reference a previous document. The DFMEA 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. All open items should be closed out prior to release of a document. At the beginning of a new design program, it is recommended that the DFMEA be approached from a “top-down” perspective and conducted initially on the “full-up” design. As the design matures, the DFMEA should be approached from a “bottom-up” perspective, beginning at the piece part level, and carried out through all the subassemblies to the top assembly.

c)The DFMEA should be prepared per the AIAG FMEA manual and this document, using COMPANY X Form F-DEM101-3. This document has also drawn extensively from the Delphi DFMEA Guidelines, which may be a useful reference tool in the preparation of a DFMEA. This manual will follow a step-by-step approach to completing the DFMEA form to minimize its completion time and insure commonality of approach at COMPANY X.

1.2Referenced Documents

All referenced documents are the current, released version/revision.

COMPANY X

F-DEM101-3Potential Design FMEA Form

AIAG

FMEAPotential Failure Mode And Effects Analysis (FMEA)

2.Completing The Header (See CIRCLED Numbers 1-5)

NOTE: Refer to the sample FMEA form in the back of this document for corresponding circled numbers.

Identify the “System:” (Inflator), “Subsystem:” (Subassembly), or “Component:” (Piece Part) being analyzed by PN. Identify the Model Year and Vehicle the inflator will be used in, if known.

The “key” date listed in the header is the date the production design is to be released and is also the planned release date of the DFMEA as a controlled document.

The FMEA document number is the prefix “DFMEA”, followed by the PN of the item being analyzed.

The preparer’s name and extension number should be included for the benefit of someone who is reviewing the document, and may have questions or comments, but doesn’t know who to contact. It is also a requirement of our quality system to identify the individual responsible for the document.

Record the date the analysis was originated, as well as the date of the last revision.

3.Completing The Footer (See CIRCLED Numbers 6-8)

It is a requirement that the names and functions of the team members who contributed to/reviewed the FMEA be recorded. Recording of job functions provides immediate evidence of the use of cross-functional teams.

Identifying the page number is a useful tool for locating the specific item under discussion during a review.

Recording the reference location of the blank FMEA form, the file location, and the date printed are useful for historical and logistical traceability.

4.Functions (See CIRCLED Number 9)

The process begins by developing a listing of what the inflator assembly, subassembly, or piece part is expected to do (and what it is expected not to do), i.e., the design intent. This is a very important step in the analysis and can only be performed by an individual intimately familiar with the design and the customer’s requirements. The better the definition of the desired functions of the item, the easier it is to identify potential failure modes for corrective action. The function list should be as concrete as possible; minimize speculation and obtain the customer’s input, if possible, as to the function of the inflator in his/her application. Each function should be listed separately. A block diagram of the functions of the item may be a useful place to start. Some examples of typical inflator assembly functions are:

Provides gas/ pressure to deploy airbag / Withstands expected vehicle dynamic environments
Interfaces with customer module / Maintains attachment to customer module
Provides structural integrity for the pressure vessel / Interfaces with vehicle/ airbag sensor electrical system
Withstands module loading conditions / Provides corrosion protection prior to assembly into module
Provides inflator traceability information / Maintains pressurant gas load in the inflator prior to actuation

NOTE: Other functions may be identified for various inflator applications.

5.Items (See CIRCLED Number 10)

The entries in this column are to be engineering specifications directly off the drawing for the component, subassembly, or top-level assembly, i.e., dimensions, notes, or items from the drawing’s parts list (subassembly & top assembly drawings). All of the dimensions, notes, etc., which affect compliance with a given function should be grouped together next to the entry for that function. Dimensions and notes may be listed more than once if they affect compliance with more than one function or more than one failure mode related to that function.

6.Potential Failure Modes (See CIRCLED Number 11)

A potential failure mode is defined as the manner in which a component, subsystem, or inflator assembly could potentially fail to meet the design intent. The potential failure mode may also be the cause of a potential failure mode in a higher level subsystem, or system, or be the effect of one in a lower level component. Avoid the temptation to focus excessively on the next-level customer application without having adequate information regarding the type of failure or its severity at that level. Obtain as much information from the customer as possible regarding failure modes, effects, and severity rankings related to COMPANY X’s inflator in their system. If this information is not readily available, confine analysis of the design to information provided in customer drawings and specifications. If more than one potential failure mode exists for each function, each mode should be listed as a separate entry behind the function. The assumption is made that the failure could occur, but may not necessarily occur. Failure modes should be described as directly as possible in terms which define a failure to perform a function, i.e., “physical” or technical terms, not as a symptom noticeable by the customer. Typical, but not all-inclusive, inflator failure modes include:

Inflator does not inflate/fill airbag (or meet closed/open tank performance envelope) / Inflator does not maintain structural integrity prior to/during actuation
Inflator will not interface with/is misoriented to customer module / Inflator does not remain attached to module before/during actuation
Inflator fails to withstand dynamic environments / Inflator does not maintain electrical interface with vehicle
Inflator fails to retain gas pressurant load prior to actuation / Inflator fails to withstand module loading conditions
Inflator corrodes excessively prior to module installation / Traceability information missing/illegible

NOTE: Other failure modes will be identified as different functions are identified.

7.Potential Failure Effects (See CIRCLED Number 12)

Potential Effects of Failure are defined as the effects of the failure mode on the function, as defined by the customer. It should be remembered that the “customer” may be internal, such as a member of the COMPANY X production department who may have to deal with the effects of a given failure, i.e., a failure of a hybrid inflator to hold pressure during the assembly process. Also, the effect of a failure in a component or low-level subassembly may be limited to the next level assembly and may not reach the top-level assembly at all. Functional failures which could impact safety or noncompliance to regulations should be identified. Speculative failure effects should be avoided. Some common inflator failure effects are:

Inflator fails to deploy when actuated / Ballistic performance compromised
Customer dissatisfaction / Customer “No-Build”
Inflator traceability lost/ returned to COMPANY X / Premature module deployment
Potential module/ airbag damage / Inflator structural integrity compromised
Inflator deploys/ partially deploys prematurely / Customer returns inflator to COMPANY X
Pressurant gas leaks prior to actuation / Inflator functions in high-output mode when low-output mode is desired (dual-output inflators)

NOTE: Other failure effects may be identified.

8.Severity Criteria (See CIRCLED Number 13)

a)Severity is an assessment of the seriousness of the effect (listed in the previous column) of the potential failure mode to the next component, subassembly, full-up inflator, next-level or OEM customer, or the final consumer level, if it occurs. Customer input, if available, is extremely valuable in making severity determinations. Severity applies to the “effect” only. The DFMEA defines the minimum severity ranking for each failure mode. Severity numbers reflect the worst-case potential effect without regard to its occurrence or detection probabilities.

b)The AIAG FMEA manual provides a list of generic severity criteria related to the automotive field. The AIAG information has been adapted to apply specifically to airbag inflators as detailed in the following list. Please note there is an attempt here to narrowly define severity rankings in quantifiable terms which are not subject to interpretation. This is done to minimize debate over the number chosen for a particular effect. The ranking system for Severity (and Occurrence and Detection numbers which follow) should be permanently attached to the DFMEA and published as a preamble of each revision.

RankingSeverity of Effect

12Additional harm imparted to user of product or system (i.e., the inflator fails to maintain structural integrity when activated).

10May affect performance of the vehicle’s safety system, compliance to governmental regulations, and/or occupant safety issues without warning (i.e., the inflator does not fire due to a defective initiator, leakage of pressurant gas (hybrid inflators), degraded or “dudded” propellant, or some other defect which registers the inflator nonfunctional).

9Same as above, except the condition is recognized with warning.

8High degree of customer (Tier 1 or OEM) dissatisfaction (i.e., inflator must be removed from module and replaced due to defect discovered after installation (recall), etc.)

7High degree of customer dissatisfaction (i.e., customer’s assembly plant shutdown due to entire inflator inventory determined to be non-usable (prior to module installation), inflator cannot be assembled into module due to defective geometry or out-of-approved-configuration condition (no-build), orientation features misaligned (module plate, flange, end plug, stud), etc.).

6Moderate degree of customer dissatisfaction (the inflator is operable, but at a reduced performance level, i.e., inflates the airbag but with a pressure vs. time curve outside the specified requirement, inflator can be installed in module only with great difficulty due to out-of-approved-configuration condition, inflator can be installed only with additional modification to the inflator or the module on the customer’s part, illegible or missing labels, etc.)

5Moderate degree of customer dissatisfaction. Customer detects deterioration of perceived quality standards (i.e., workmanship and cosmetic appearance of inflator, weld blemishes which do not affect inflator structural integrity, variability in crimp appearance or other visible features despite demonstrated functional capability, propellant rattle, out-of-position or damaged, but legible, labels, etc.).

4Moderate degree of customer dissatisfaction. Vehicle customer does not detect defect, but perceives standard for quality is low (i.e., corrosion on exterior of inflator, variation/inconsistencies in inflator finish or appearance, etc.).

3Low customer annoyance if detected (i.e., discoloration in inflator appearance, poor paint or coating finish, etc.).

2Low customer annoyance (i.e., occasional minor scratches and nicks on inflator surface, nonstructural shipping damage, etc.).

1Customer cannot detect condition or results of failure (internal, non-degrading corrosion, pre-sheared shear ring (Gen II PSIR), etc.

9.Classification (See CIRCLED Number 14)

This column should be used to highlight any ‘Special Characteristics’, as defined in QSP104, that have been identified for components, subassemblies, or full-up inflators that require additional process controls. In addition, if the DFMEA identifies any failure modes which fall under one of the following conditions, the failure mode must be identified as a Special Characteristic until the Special Characteristics Index (SCI) analysis, as specified in DEM101, can be conducted on the condition and a final decision made as to whether the Special Characteristic symbol must continue to be applied:

a)6-2-1 Rule: If the Severity ranking of a particular failure cause/mechanism is greater than or equal to six (S≥6), and the Occurrence ranking is greater than or equal to two (O≥2), the Detection ranking must be a one (D=1). Conversely, if Detection in a specific example can never be less than a 2 (D=2), then Occurrence must be a one (O=1). If neither of these conditions is met by the initial DFMEA analysis, the SCI analysis must be performed.

b)O≥4 Rule: If the Occurrence ranking is greater than or equal to 4, then Severity must be less than or equal to 5 (S≤5). If this condition is not met by the initial DFMEA analysis, the SCI analysis must be performed.

10.Potential Causes (See CIRCLED Number 15)

The potential cause or mechanism for a failure is an indication of a design weakness, the consequence of which is the failure mode. List, to the extent possible, every conceivable failure 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. In a Design FMEA, all failure causes/ mechanisms should be limited to design-related issues. Process-related failure causes/mechanisms will be covered in the PFMEA. Typical design-related causes/mechanisms at COMPANY X include, but are not limited to:

Incorrect Material/Properties/Process Specified / Part Overstressed (not designed to handle load)
Incorrect Algorithm / Improper Drawing Dimensions/Tolerances Specified
Inadequate Weld Size/Chemistry/Geometry Specified / Improper Joint Design
Improper Booster/Propellant/Gas Quantity Specified / Improper Gap/Fit/Seal Between Mating Parts Specified
Inadequate Fatigue Resistance Specified / Excessive/Inadequate Flow Area

11.Occurrence (See CIRCLED Number 16)

“Occurrence” is the likelihood that a specific cause/mechanism (listed in the previous column) will occur. Occurrence should be based on actual statistical data for the condition based on similar designs, if available. By definition, the failure mode “occurs” when a vendor/COMPANY X internal/customer source identifies an out-of-tolerance condition. Once an “occurrence” number is assigned, removing or controlling one or more of the causes/mechanisms of the failure mode through a design change is the only way a reduction in the occurrence ranking can be effected. The following is a suggested ranking system for occurrences:

RankingIncidents*

1060,000

930,000

815,000

71,500

6150

580

415

*Based upon actual supplier or COMPANY X internally-identified incidents and customer returns for the identified failure mode per 1,000,000 units (PRRo/PPMo) containing a similar design function and failure mode.

12.Current Design Controls (See CIRCLED Number 17)

a)List the prevention, design verification/validation (DV), detection, and other activities which will assure the design’s adequacy for the failure mode and/ or cause/ mechanism under consideration. Current controls (e.g., inspection and test programs, design reviews, mechanical analyses, mathematical & statistical studies, sample testing, feasibility reviews, prototype tests, field (fleet) testing) are those that have been or are being used with the same or similar designs. There are three types of Design Controls/Features to consider; those that: