BME FACULTY OF TRANSPORTATION ENGINEERING AND VEHICLE ENGINEERING

FMEA

Wahl István – 2019.04.02./04.09.

KOGGM614JÁRMŰIPARI KUTATÁS ÉS FEJLESZTÉS FOLYAMATA

2

Tartalomjegyzék

Siker és kudarc faktor

Minőségi célok

5 lépés módszer

FMEA típusok

Töténelmi háttér

Rövidítések

3

Rövidítések

• BOM: Bill of Materials

• FMEA: Failure Mode and Effects Analysis

• OEM: Original Equipment Manufacturer

• RPN: Risk Priority Number

• SBS: System Breakdown Structure (SBS) –

Rendszerfelépítés

• TIER1: supplying components directly to the OEM

• TIER2: supplying components directly to the TIER1

4

A sad story

• On January 28, 1986 NSAS launched Space Shuttle ‘Challenger’, which

ended with an explosion.

• The investigation identified that it was a failed O-Ring at the right end of

the mid segment field joint that led to a breach failure that permitted

spewing, burning rocket fuel to invade the External Fuel Tank ultimately

causing the Solid Rocket Booster (SRB) and the fuel tank to inadvertently

separate

• As a result, NASA adopted qualitative failure modes and effects analysis

(FMEA) as its principal means of identifying design features whose worst-

case failure could lead to a catastrophe.

Source: Kouroush Jenab at all: ‚Effective FMEA Analysis or Not?’, June 2015

5

Az FMEA története

• since 1959 NASA develops FMEA method for Apollo-Project. FMEA FMEA

was one of the earliest structured reliability improvement methods

• since 1965 applied to aircraft industry

• since 1975 applied to nuclear power engineering

• since 1977 first application in automotive industry (FORD)

• in 1980 standardization in Germany as „Ausfalleffekt-Analyse“ (DIN 25448)

• since 1986 increased application in German automotive industry

• applied to different industries: Electronics, Software, Chemistry,

Pharmaceuticals, Medicine engineering,...

• VDA 1996 System-FMEA

• increasing demand on the application of FMEA by ISO 9000:2000; FDA;

GMP etc. causes increased application in pharmaceutical industry,

medicine engineering, and food industry

6

Miért szükséges az FMEA?

FMEA is a structured approach to discovering potential failures that

may exist within the design of a product or process, which could

be applied in case of…

• Newly developed products

• Changes of existing products

• New environmental conditions / constraints for existing products

• Process changes

• Poor process capability

• Use of new machines, tools

• Risk for environment/operator

• Minimize probability for a recall / costs of a recall

• Feedback from field claims

[What is the purpose of applying FMEA during product development?]

7

Basic interrelation between different types of FMEAs

Failure Mode Effect Cause

ProblemRamifications of

the ProblemCause(s) of the

Problem

Failure Mode Effect Cause

Cause(s) of the Problem from the

S-FMEA

Effect from the S-FMEA with perhaps a better definition

New root causesfor the design failure modes

Failure Mode Effect Cause

Cause(s) of the Problem from the

D-FMEA

Same effect as the D-FMEA

Specific root causesfor the process failure modes

System FMEA

Design FMEA

Process FMEA

[What types of FMEA are applied during product development?]

8

FMEA activities during product development

Concept Phase

Feasibility Phase

Product Design

Process Development

A-Sample B-Sample C-Sample Preproduction-Sample

Series-Sample

Q1 Q2 Q3 Q4 Q5

Tooling Preproduction Series Production

Requirement Freeze

Design Freeze

Validation Passed

[Until when the D-FMEA has to be created?]

SFMEA has to be created at the concept phase to recognize risks at an early stage.

DFMEA has to be created at this time to be most effective, but latest by design freeze.

PFMEA has to be created with the start of the serial development

S-FMEA D-FMEA P-FMEA

9

FMEA analysis principle

Product (System, Design) FMEA explores the possibility of product

malfunctions, reduced product life, and safety and regulatory concerns derived

from

• Material Properties

• Geometry, Tolerances

• Interfaces with other components and/or systems

• environments, user profile, degradation, systems interactions

Process FMEA discovers failure that impacts product quality, reduced

reliability of the process, customer dissatisfaction, and safety or environmental

hazards derived from

• Human Factors

• Methods followed while processing

• Materials used

• Machines utilized

• Measurement systems impact on acceptance

• Environment Factors on process performance

10

5 step for the preparation of FMEA

Source: VDA Volume 4 – Product and Process FMEA

System analyses Risk analyses and improvements

Record and structure the elements involved

Creating systemstructure

Step 2 Step 3 Step 4 Step 5

Structure analysis Function analysis Failure analysis Actions analysis Optimization

Assigning functions to the structure elements

Link functions

Assigning failures to the functions

Link failures

Document current preventive and detection measures

Evaluate current status

Reducing riskswith furthermeasures

Evaluate changed status

Step 1

[What are the 5 steps of executing an FMEA?]

11

Step 1. Structure analysis

Source: VDA Volume 4 – Product and Process FMEA

Objectives:

• Overview of the inspected product

• Reuse of modules

• Classification and interface description

• Establish responsibilities

12

Step 2. Function analysis

Source: VDA Volume 4 – Product and Process FMEA

Objectives:

• Overview of the functionality of the product

• Overview of the cause-effect relationship

• Verification against the customer requirements

• Basis for the failure analysis

13

Step 3. Failure analysis

Source: VDA Volume 4 – Product and Process FMEA

Objectives:

• Identification of the possible failures, assigned to

system structure and functions

• Links of the failures to the failure structure

• Basis for the illustration of failures in a form an and/or

the preparation of the form

14

Step 4. Actions analysis

Source: VDA Volume 4 – Product and Process FMEA

Objectives:

• Assigning the existing and/or already established

actions to the failure

• Risk evaluation

15

Step 5. Optimization

Source: VDA Volume 4 – Product and Process FMEA

Objectives:

• Identification of the actions necessary for improvement

• Assessment of the risk

• Checking the effectiveness of the implemented actions

• Documenting the implemented actions

16

D-FMEA form

Source: QS9000 FMEA 4th edition, 2008

FUNCTION

ANALYSISFAILURE ANALYSIS RISK

EVALUATIONOPTIMIZATION

17

Risk evaluation

O S D

likelihood of Occurrence (causes)

Severity(effects)

likelihood of Detection (causes,

failure modes)

O = Cause – d(P-actions)

S = EffectD = 10 – d(D-

actions)

Range [1..10] Range [1..10] Range [1..10]

Risk Priority Number (RPN) = O x S x D Range [1..1.000]

If RPN1 is higher than 99, action shall be determined to reduce the risk

Risk Matrix

[How the RPN could be calculated?]

18

Example – Disk Brake

Before you begin:

• Define the focus of the FMEA

• Check boundary diagrams

• Define System Breakdown

Structure (SBS)

• Create Bill of Materials (BOM)

• Get a rough overview of the main

functions (P-Diagram)

19

Example - Potential failure modes

Source: QS9000 FMEA 4th edition, 2008

20

Example - Potential effects

Source: QS9000 FMEA 4th edition, 2008

21

Example - Potential causes

Source: QS9000 FMEA 4th edition, 2008

22

Suggested D-FMEA Severity evaluation criteria

Source: SAE J1739

23

Suggested D-FMEA Occurrence evaluation criteria

Source: SAE J1739

24

Suggested D-FMEA Detection evaluation criteria

Source: SAE J1739

25

Prevention and Detection controls

Source: QS9000 FMEA 4th edition, 2008

Prevention Controls:

• Benchmarking studies

• Fail-safe design

• Design and Material standards

• Documentation – record of best

practices, lessons learned from

similar design

• Simulation studies – analysis of

concepts to establish design

requirements

• Error proofing

Detection Controls:

• Design reviews

• Prototype testing

• Validation testing

• Simulation studies – validation of

design

• Design of Experiments, including

reliability testing

• Mock-up using similar parts

Prevention control: what can be done to prevent the failure cause?

Detection control: what can be done to detect the failure cause?

[What are the typical Detection Controls of an FMEA?]

26

Example - Prevention and Detection Design Controls

Source: QS9000 FMEA 4th edition, 2008

27

Recommended Action

Source: QS9000 FMEA 4th edition, 2008

• Prevention actions (e.g. reducing Occurrence) are preferable than

Detection actions.

• The target of Recommended Action is to improve the Design.

Reduce Severity ranking:

• Only by Design revision

Reduce Occurrence ranking:

• Error proof the Design to eliminate

the failure mode

• Revised Design geometry and

tolerances

• Revised Design to lower the stresses

or replace weak components

• Add redundancy

• Revised material specification

Reduce Detection ranking:

• Design of Experiments

(particularly when multiple

or interactive causes of a

failure mode are present)

• Revised test plan

[What is the main target of defining Recommended Actions in an FMEA?]

28

Example – Causes, Controls and Recommended Actions

Source: QS9000 FMEA 4th edition, 2008

29

Resulting RPN

• After the Prevention / Correction actions have been taken,

determine the resulting Severity, Occurrence and Detection

rankings.

• Calculate the resulting Risk Priority Number.

• If further action is considered necessary, than the analysis and

the optimization should be repeated.

30

Quality objectives of D-FMEA

Source: SAE J1739

[What are typical quality objectives of an FMEA?]

1. DESIGN IMPROVEMENTS: The FMEA drives Design Improvements as the primary objective.

2. HIGH RISK FAILURE MODES: The FMEA address 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 (DVD&R) considers the failure modes from the Design 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 the procedure. As appropriate, a facilitator should be utilized.

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.

31

Special or critical Characteristics

Source: VDA4 – Product and Process FMEA

• C/C (Critical Characteristics): product

characteristics or process parameter that

influence the safety of a product or the

compliance to legal regulation.

• S/C (Special Characteristics): product

characteristics or process parameter that

influence the fit/function of a product, or which

have to be controlled and documented for other

reasons, such as customer requirements.

• S/C and C/C are part of the Control Plan,

which provides the process monitoring and

control methods that will be used to control

characteristics.

• If S=9..10 and O>1 than C/C

• If S=8 and O≥4 than S/C

32

Interface to customer & supplier FMEAs

• Customers can review

FMEA’s only in the

presence of the company

representative

• FMEA’s are not to be sent

or left with customers

• An FMEA summary is given

to the customer if

requested

• The customer has to be

informed of high product

risks and all customer

influenced risks

OEM

TIER1

TIER2

functions, failures,

severities

functions, failures,

severities

failure causes, actions, risk?

failure causes, actions, risk?

33

Success and Failure factors of an FMEA

Source: QS9000 FMEA 4th edition, 2008

Success factors:

• Support by top management

• Involving specialists of different

departments, customer and

supplier

• Ability to work in a team

• Ability to communicate

• Knowledge of the FMEA method

• Scheduled meetings and enough

time

Failure factors:

• Preparation of the project is not

appropriate

• Missing goals

• Poor knowledge of the method

• The top management is not

supporting

• No action tracking

• The rules of team work are not

defined or not applied

• The team members are not

active

[What are the success factors of an FMEA?]

BME FACULTY OF TRANSPORTATION ENGINEERING AND VEHICLE ENGINEERING

Wahl, István

BUDAPEST UNIVERSITY OF TECHNOLOGY AND ECONOMICS