Design Failure Mode & Effect Analysis, Design Review & Design Validation Plan

(DFMEA, DR & DVP)

Dr K C Vora Deputy Director & Head,

ARAI Academy, ARAI

New Product Development (NPD) Concept Phase

Definition Phase

Design Phase

Production Phase

Feasibility studies

Formulate development

policy

List operational

requirements

Draft several

scheduling proposals

Make tradeoffs

Define system specifications

Solicit bids (when using

subcontractors)

General design

Detailed design

Make prototypes

Prototype testing

Qualification testing

Production process design

Jigs, tools & equipment

Pilot production

Pilot evaluation

Full production

startup

Product launch

Market stage

RELATIONSHIP MATRIX

OR QFD TABLE- 1

OR QUALITY TABLE-1

CUSTOMER REQUIRE MENTS

OR CR

DESIGN TARGETS.

TECHNICAL BENCHMARKING

SERVICE CONCERNS

CONCEPT DEVELOPMENTTABLE

COST ISSUE BNE ISSUES

BENCHMARKING BY CUSTOMER CUSTOMER

COMPLAINT DATA CUSTOMER

IMPORTENCE

QUALITY ELEMENTS Q-CHARACTERSTIC

QUALITY ELEMENTS CONFLICT IDENTIFICATION TABLE

QUALITY PLANNING

PRODUCT PLANNING.

RELIABILITY TARGETS

TECHNICAL STUDY ITEMS

BOTTLENECK TECHNOLOGY ISSUES

SUBSYSTEM MECHANISM - AA

IMPACTED COMPONENTS

A , B ,C FMEA table

FUNCTION & FT DIAGRAM

ACTION PLAN TABLE

VOC

House of Quality

DFMEA

• FAILURE MODES & EFFECTS ANALYSIS (FMEA) is a paper-and-pencil analysis method used in engineering to document and explore ways that a product design might fail in real-world use.

• Failure Mode & Effects Analysis is an advanced quality improvement tool.

• FMEA is a technique used to identify, prioritize and eliminate potential failures from the system, design or process before they reach the customer.

• It provides a discipline for documenting this analysis for future use and continuous process improvement.

FMEA

• Historically, FMEA was one of the first systematic techniques for failure analysis developed by the U.S. Military on 9th November, 1949. FMEA was implemented in the 1960’s and refined in the 70’s. It was used by reliability engineers working in the aerospace industry. • Then the Automotive Industry Action Group formed by Chrsyler, Ford & GM restructured the FMEA techniques which found a lot of importance in the automotive industry. • Since then FMEA has been instrumental in producing quality goods in the automotive sector.

History of FMEA

Types of FMEAs

• Design –Analyzes product design before release to

production, with a focus on product function. –Analyzes systems and subsystems in early

concept and design stages.

• Process –Used to analyze manufacturing and assembly

processes after they are implemented.

• SYSTEM FMEA - Chassis system - Engine system - Transmission • COMPONENT FMEA - Piston - Crankshaft

Types of DFMEA

DFMEA: Starts early in process. It is complete by the time preliminary drawings are done but before any tooling is initiated.

PFMEA: Starts as soon as the basic manufacturing methods have been discussed. It is completed prior to finalizing production plans and releasing for production.

FMEA Timeline

MIL-STD 1629, “Procedures for Performing a Failure Mode and Effect Analysis”

IEC 60812, “Procedures for Failure Mode and Effect Analysis (FMEA)”

BS 5760-5, “Guide to failure modes, effects and criticality analysis (FMEA and FMECA)”

SAE ARP 5580, “Recommended Failure Modes and Effects Analysis (FMEA) Practices for Non-Automobile Applications”

SAE J1739, “Potential Failure Mode and Effects Analysis in Design (Design FMEA)”

SEMATECH (1992,) “Failure Modes and Effects Analysis (FMEA): A Guide for Continuous Improvement for the Semiconductor Equipment Industry”

Standards

• They can only be used to identify single failures and not combinations of failures • Failures which result from multiple simultaneous faults are not identified by this • Unless adequately controlled and focused, the studies can be time consuming • They can be difficult and tedious for complex multi-layered systems • They are not suitable for quantification of system reliability

Limitations of FMEA

Responsibility and scope of DFMEA • The DFMEA is a team function

– All team members must participate – Multi-disciplinary expertise and input is beneficial

• Input from all engineering fields is desirable • Representatives from all areas (not just technical

disciplines) are generally included as team members • The DFMEA is not a one meeting activity

– The DFMEA will be refined and evolve with the product – Numerous revisions are required to obtain the full benefit of

the DFMEA • The DFMEA must include all systems, sub-systems and

components in the product design

• Form the cross functional team. • Call FMEA Meeting with advance intimation. • Complete the top of the form

– Project, year, team members, date, and DFMEA iteration – There will be many iterations

• List items and functions – Start with the system, then subsystems and finally components

• Document potential failure modes – How could the design potentially fail to meet the design intent? – Consider all types of failure

• Document the potential effects of failure – How would design potentially fail to meet the design intent?

Steps to conduct DFMEA

• Rate the severity of the failure effect – See ranking guidelines – Severity ranking is linked to the effect of the failure

• Document potential causes and mechanisms of failure – Failure causes and mechanisms are an indication of design

weaknesses – Potential failure modes are the consequences of the failure causes – A single failure mode may have multiple failure mechanisms – Use group brainstorming sessions to identify possible failure

mechanisms – Don’t be afraid to identify as many potential causes as you can – This section of the DFMEA will help guide you in necessary design

changes – The output of the DFMEA will indicate on which item to focus

design efforts

• Rate the occurrence – See attached page for ranking guidelines – Things that may help you rate the occurrence

• Are any elements of the design related to a previous device or design?

• How significant are the changes from a previous design? • Is the design entirely new?

• List the design controls – Design controls are intended to:

• Prevent the cause of the failure mode (1st choice solution) • Detect the cause of the failure mode (2nd choice solution) • Detect the failure mode directly (3rd choice solution)

– Applicable design controls include • Predictive code analysis, simulation, and modeling • Tolerance “stack-up” studies • Prototype test results (acceptance tests, DOE’s, limit tests) • Proven designs, parts, and materials

• List any critical or special characteristics – Critical characteristics: Severity > 8 and Occurrence >1 – Special characteristics: Severity > 6 and Occurrence >2

• Detection rate – See attached page for ranking guidelines

• Calculate the RPN of each potential failure effect – RPN = (Severity) x (Occurrence) x (Detection) – What are the highest RPN items?

• Define recommended actions – What tests and/or analysis can be used to better understand the

problem to guide necessary design changes ?

• Assign action items – Assemble team – Partition work among different team members – Assign completion dates for action items – Agree on next team meeting date

• Complete “Action Results” Section of DFMEA – Note any work not accomplished (and the justification

for incomplete work) in the “actions taken” section of the DFMEA. • Why was nothing done?

– Change ratings if action results justify adjustment, but the rules are: • Severity: May only be reduced through elimination

of the failure effect • Occurrence: May only be reduced through a design

change • Detection: May only be reduced through

improvement and additions in design control (i.e. a new detection method, better test methodology, better codes, etc.)

– Include test and analysis results with DFMEA to validate changes.

19

Potential Failure Mode and Effects Analysis

(Design FMEA)

__ System __ Subsystem __ Component Model Year/Vehicle(s): Core Team:

Design Responsibility Key Date:

FMEA Number: Page 1 or 1 Prepared by: FMEA Date (Orig.):

Item

Function

Potential Failure Mode

Potential Effect(s) of

Failure

Potential Cause(s)/

Mechanism(s) Of Failure

Current Design

Controls Prevention

Current Design

Controls Detection

Recommended

Action(s)

Responsibility

& Target Completion

Date

Actions Taken

Action Results S E V

C L A S S

O C C U R

D E T E C

R. P. N.

S E V

O C C

D E T

R. P. N.

The FMEA Form

Identify failure modes and their effects Identify causes of the

failure modes and controls

Prioritize Determine and assess actions

Subsystem

Function Requires

Potential failure mode

Potential Effect(s)

of Failure

S E V

C L A S S

Potential Cause(s)

Mechanism(s) of

Failure

O C C U R

Current Controls D E T E C T ION

R PN

Recommended

Action(s)

Responsibility & Target

completion date

Action results

Act-ions

taken

S E V

O C C

D E T

R. P. N.

What are the Functions, Features or

Require-ments?

What can go wrong? - No function - Partial/ over/ degraded function - Intermittent function - Unintended function

What are the effect(s)?

How bad is it?

What are the

cause(s)?

How often does it

happen?

How can this be prevented

and detected?

How good is this method at

detecting it?

What can be done? - Design changes - Process changes - Special controls - Changes to standards, procedures, or guides

FMEA Sequence

Recommend improvements

Look possible causes & mechanism for failures mode

Consider effects, if above failure mode happens

Assess the frequency of occurrence of

failure modes (O)

Assess the possibility of Failure being detected ( D )

Assess the Severity of effect (s)

List all conceivable failure modes

Calculate the Risk Priority Number (RPN)

Re- evaluate (New RPN )

Define Responsibility & Time- frame

FMEA Procedure List all Function &

requirements

Functions & Requirements

• Functional Requirements • Customer Requirements • Legal Requirements • Benchmarking Requirements • State of the Art Trend

Function & Function Tree Function means what the product does, and is normally considered in a dynamic sense, expressed as

Verb + object - (There could be a number of functions for a product or its sub assy. Or part.)

Example – • Can drive with stability, • Generates electricity, • Propels airplane, • Some time cd be given as static expression by noun + adjective– • Easy handling, good look, quite sound, • Also expressed as adverb – • Rotate smoothly • Basic functions are expressed by verb + Object

• Analyze the vehicle / engine / system / components and summarize various functions and failure modes.

• Conduct DFMEA various components/systems.

•These components & systems all had failure modes and a corresponding Risk Priority Number (RPN) to be calculated using severity, occurrence & detection rankings.

•The idea is to reduce this RPN value so that the components/systems are designed more towards reliability and safety. These reductions are to be done through design changes.

Motivation

Famous Failures

Failure Definitions

Failure: (Noun) 1a- Omission of occurrence or performance, specifically a failing to perform a duty or expected action 1b- A state of inability to perform a normal function 1c- A fracturing or giving away under stress 2.- A lack of success 3.- A falling short or deficiency Deterioration or decay

Failure Definitions Fail: (Noun) (a) - To lose strength: Weaken To fade or die away To stop functioning To fall short To be absent or inadequate To be unsuccessful ( b) - To miss performing an expected service or function To be deficient in: Lack To leave undone: Neglect To be unsuccessful in passing (like a test)

Failure Categories Failure Categories

• Reliability • Catastrophic • Complete • Critical • Degradation • Dependent • Gradual

• Independent • Inherent

Weakness • Intermittent • Major • Minor • Misuse • Non-relevant

• Partial • Primary • Random • Relevant • Secondary • Sudden • Wear-out

How We Call a Failure ? 1. Unsuccessful (Not meeting design intent)

2. Deteriorating (Not to standards)

3. Defective (Imperfection, flaw)

4. Decaying (Gradual or sudden decline)

5. Deficient (Impaired or inferior; weak)

6. Incomplete (Inadequate)

7. Non-Functional (Doesn’t work)

8. Omission (Overlooked, neglected, missed)

Examples Unsuccessful: A required function is wrong Example: Wrong firing sequence in engine

Deteriorating: A measured value does not meet an established level Example: Engine power does not qualify to a defined level

Defective: A part has a physical flaw Example: Crack in the engine casting

Decaying: A measured value has changed from an initial baseline level Example: Head lamp light lux level reduction over time

Examples Deficient: A material or product is not capable of meeting requirements Example: Strength of con-rod deficient due to selected material grade. Incomplete: One or more expected functions or outputs are missing Example: Kombi –switch does not provide for night light dipping. (not considered by development) Non-Functional: The component is not working or responding to commands Example: Kombi –switch does not function for command for night light dipping ( considered in dev, but not performing ) Omission: A required characteristic has not been designed or measured Example: Water pressure in radiator not considered in design

Failures modes – • Concept of failure mode is fundamental to FMEA • A failure mode is not a failure in itself, it is a class of undesirable phenomena that can result in failure. • Failure mode is also not a actual cause of failure. • Wire break, short circuit, adhesion, surface roughness, leakage, detachment, slackness, blockage, deformation, snapping, cracking, loss are few examples of failure mode.

CAUSE Cause of failure mode

FAILURE-MODE FAILURE Effect of failure mode

Failures & Failure Modes

CAUSE Leakage ( Oil / Gas )

FAILURE

CAUSE - • Wrong oil selection • Wrong gasket • wrong workmanship • Over filling • Wrong breather • Deflection

Oil leakage • FAIURES - • Engine stalling • Over Heating • Air entrapping • Others

Failures & Failure Modes

Severity, Occurrence & Detection

35

• Severity – Importance of the effect on customer

requirements

• Occurrence – Frequency with which a given cause occurs and

creates failure modes

• Detection – The ability of the current control scheme to detect

or prevent a given cause

Probability of Failure Possible Failure Rates Ranking Very High : Persistent

failures > 100 per thousand vehicles/ items 10

50per thousand vehicles/ items 9

High : Frequent failures 20 per thousand vehicles/ items 8

10 per thousand vehicles/ items 7 Moderate : Occasional

failures 5 per thousand vehicles/ items 6

2 per thousand vehicles/ items 5

1 per thousand vehicles/ items 4

Low : Relatively few failures

0.5 per thousand vehicles/ items 3

0.1 per thousand vehicles/ items 2

Remote : Failure is unlikely

< 0.010 per thousand vehicles/ items 1

Occurrence (O) Table

Effect Criteria : severity of Effect Ranking 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.

10

Hazardous with warning

Very high severity ranking when a potential failure mode affects safe vehicle 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 customer (less than 25%).

2

None No discernible effect. 1

Severity (S) Table

Detection Criteria : Likelihood of Detection by Design Control Ranking Absolute

Uncertainty Design control will not and/or can not detect a potential cause/ mechanism an subsequent failure mode; or there is no Design control

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

Moderate High Moderate 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 an subsequent failure mode.

1

Detection (D) Table

Risk Priority Number (RPN)

RPN is the product of the severity, occurrence, and detection scores.

Severity Occurrence Detection RPN X X =

RPN / Risk Priority Number

Top 20% of FailureModes by RPN

RPN

Failure Modes

Example of Significant / Critical Threshold

10 9 8 7 6 5 4 3 2 1

1 2 3 4 5 6 7 8 9 10

S E V E R I T Y

O C C U R R E N C E

POTENTIAL CRITICAL CHARACTERISTICS Safety/Regulatory

POTENTIAL SIGNIFICANT

CHARACTERISTICS Customer Dissatisfaction

ALL OTHER CHARACTERISTICS Appropriate actions /

controls already in place

Special Characteristics Matrix

ANOYANCE ZONE

FMEA Inputs and Outputs

FMEA

a

Brainstorming Process Map

Process History Procedures Knowledge Experience

List of actions to prevent causes or detect failure

modes

History of actions taken

Inputs Outputs

Action • Recommend Action, wherever RPN is high through - Design Controls - Design changes - Process changes - Special controls changes to

standards/procedures/guidelines

• Decide Responsibilities • Decide Target date of completion.

Repeat: undertake the next revision of the DFMEA

The DFMEA is an evolving document! Revise the DFMEA frequently & keep on reducing RPN! Diligence will eliminate design risk! Include documentation of your results!

What Next?

Design Review (DR)

Steps for NPD

PRODUCT CONCEPT

CONCEPTUAL DESIGN

OUTLINE DESIGN

DETAILED DESIGN

PROTOTYPE MAKE

TRIL RUN

INITIAL PRODUCTION

MASS PRODUCTION

PRODUCTION PREPARATION

SUPPLIER PREPARATION

DR1

DR2

DR3

DR4

DR5

?

DR Phase Planning

Design Engineer; System Engineer, System Experts, Process Engineer; Product Planner, Manufacturing Engineer, Sourcing Engineer; Reliability Engineer; Service Engineer; Contribution by Participants: Participants should come to the meeting along with the data worked out and results relevant to their roles/expertise required under "preparation list" and leading to "deliverables ".

Participants for Design Review

• Intent & concept definition of project • Application details & translated to Technical requirements • Design Inputs • Customer Requirements - VOC; RWUP translated to technical

requirements • Deliverables- performance & endurance; Reliability goals • Benchmark & competition data • Information of failures /successes of similar products, competitor

product • Metallurgical data • Cost data • Design calculations of performance, endurance, strength

requirements of system/ components • Homologation requirements • Legal regulation • Layout & detail drawings of system • Operational ergonomic requirement data • Assembly build variation analysis.

Preparation for Design Review

Conformance of design to the intent & concept for performance, endurance & warranty. Conformance of design to strength Conformance to regulations & homologation Manufacturability aspects Serviceability aspects Identification of special/ stranger technology Use of standard products Use of standard materials Identification of patent issues- a) use of present- legal matters; b) patentable features Identification of overlapping & interdependent areas between Interfacing systems Identification of environmental issues Operational ergonomic conformance.

Deliverables of Design Review

Design Validation Plan

(DVP)

Design Validation Plan (DVP) • Design Validation is next step to DFMEA.

• Depending upon RPN in DFMEA, the components

are arranged in DVP. • It contains all the information regarding the

acceptance criteria, responsible person or team, type of test and start & finish dates.

Why Design Validation? • ‘Are we building it right?’ • Major costs of projects are incurred in early design

stages. • The cost of fixing a design and faulty decisions at later

stages is exponentially greater than at an earlier stage.

• Early Validation/Verification: reduces risk early in the program provides feedback to designers before delivery proves that requirements are met saves costs reduces complexity of fault detection

Validation Definition

The documented act of proving that any procedure, process, equipment, material, activity or system, actually leads to the expected results.

Design Validation means establishing by

objective evidence that device specifications conform to user needs and intended uses.

55

Design, Build & Verify

56

Design Verification Catalogue (DVC) The Design Verification Catalogue (DVC) allows the System Engineers to verify that the vehicle / system / sub-system / component meets the design specifications appearing in corresponding VDS / SDS / CDS. • DVC serves to, describe appropriate Design Verification Methods (DVM) associate one or more verification methods with each

SDS requirement capture facility and prototype requirements to conduct

planned verifications.

DVC includes the operating conditions, accuracy and uncertainty of the test.

Requirements of Design Validation

• Design validation shall be performed under defined operating conditions on initial production units, lots or batches, or their equivalents.

• It includes testing of production units under actual or simulated use conditions.

• It includes software validation and risk analysis. • The Validation must be documented in Design

Validation Plan.

Design Validation Process

• Validation Plan

• Validation Review

• Validation Methods

• Validation Report

Comparison Between Validation, Verification & Review

Validation Methods

• Testing ( Static as well as Dynamic)

• Analysis ( Using software's and simulations)

• Inspection Methods(Visual or with Test Rigs)

• Compilation of relevant scientific literature

• Study of historical evidences of similar design

Examples of validation methods & activities

• Worst case analysis of an assembly. • Fault tree analysis of a process or design. • Failure modes and effects analysis (FMEA). • Package integrity tests. • Testing of materials. • Comparison of a design to previous vehicles having

an established history of successful use.

For design of high performance products / systems / components, quality tools like DFMEA plays an important role to achieve desirable performance and durability requirements. If this is done right from concept stage, the risk of failures substantially reduces and lot of time, energy and cost is saved. Design Review is a continuous process of conforming that the design to the intent & concept for performance, endurance & warranty is foolproof. Design Validation Plan is a systematic plan to confirm that the design meets the desired target after verification.

Conclusion