STANDARD
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FMECA (FAILURE MODES THEIR EFFECTS AND CRITICALITY CRITICALITY ANALYSIS) ANALYSIS) VISA RESPONSABLE(S) NOM : SERVICE : DATE : SIGNATURE :
Classement prévu : 01 01 - 33 - 200 / - - A Respons Res ponsabl able e du doc docume ument nt
Sce
N° Té Tél
F. SCH SCHWA WARTZ RTZ
65810
53133
C. CARUEL
65850
57218
Pilote(s) technique(s)
Date de mise à jour :
22/05/00
Normalisation Renault Automobiles Automobiles Service 65810 Section Normes et Cahiers des Charges
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RENAULT
This document is to be considered as a whole, the parts of which must not be separated. © RENAULT 2000. No duplication permitted without the consent of the issuing department. No circulation permitted without the consent of RENAULT.
FIRST ISSUE December 1986
---
REVISIONS Nov ember 2000
- - A Complete rev ision. This issue issue originates originates from draft draft NC 1999 0171 0171 / - - B.
REFERENCED DOCUMENTS Quality Rule
:
Q00 41 C.
CNOMO Standard
:
E41.50.530.N.
© RENAULT RENAULT 2000
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RENAULT
This document is to be considered as a whole, the parts of which must not be separated. © RENAULT 2000. No duplication permitted without the consent of the issuing department. No circulation permitted without the consent of RENAULT.
FIRST ISSUE December 1986
---
REVISIONS Nov ember 2000
- - A Complete rev ision. This issue issue originates originates from draft draft NC 1999 0171 0171 / - - B.
REFERENCED DOCUMENTS Quality Rule
:
Q00 41 C.
CNOMO Standard
:
E41.50.530.N.
© RENAULT RENAULT 2000
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RENAULT CONTENTS
Page GLOSSARY
5
1. FIELD OF APPLICAT ION
6
2. DEFINIT IONS
7
3. BASIC PRINCIPLE
8
4. DETAILED PROCEDURE
11
4.1. STEP 1: INITIALIZATION
11
4.1.1. Selecting the subjects to be dealt with
11
4.1.2. Organizing the FMECA study
12
4.2. STEP 2: ANALYSING
13
4.2.1. Preparing the FMECA
13
4.2.2. Identifying potential failures
14
4.3. STEP 3: EVALUATING - DECIDING
17
4.3.1. Evaluation principle
18
4.3.2. Rating degrees
19
4.3.3. Criticality calculation
19
4.3.4. Hierarchy grading
19
4.3.5. Deciding which are the priority corrective actions
20
4.4. STEP 4: FINDING SOLUTIONS
21
4.5. STEP 5: FOLLOW-UP
22
4.6. STEP 6: APPLICATION
23
4.7. STEP 7: VERIFICAT ION - KNOWLEDGE TRANSFER
23
4.7.1. Verification principle
23
4.7.2. Knowledge transfer
25
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RENAULT CONTENTS (continued) ANNEX 1 SYNTHESIS SHEET (FORMAT A4)
27
ANNEX 2 CHOOSING THE SUBJECTS TO BE DEALT WITH FOR THE PRODUCT FMECA
28
ANNEX 2 (continued) CHOOSING THE SUBJECTS TO BE DEALT WITH FOR THE PROCESS FMECA
29
ANNEX 2 (continued) CHOOSING THE SUBJECTS TO BE DEALT WITH FOR THE FLOW FMECA
30
ANNEX 3 LIST OF BASIC DATA AND FUNCTIONAL ANALYSIS TO BE CONDUCTED PER TYPE OF FMECA
31
ANNEX 4 PRESENTATION OF THE ANALYSIS GRILLE
32
ANNEX 5 RATING SCALES
33
ANNEX 6 RATING SCALES
35
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RENAULT GLOSSARY
FMECA
:
Failure Modes, their Effects and Criticality Analysis.
AMPPP3 : :
Accord de Montage Prototype Produit / Process phase 3. Product / Process Prototype Assembly Go-Ahead, phase 3
APV
:
Après-Vente. After-Sales
CdC
:
Cahier des Charges. Product Specifications
DDHA
:
Direction de la Détection, Hiérarchisation et Affectation des incidents clients. Customer Incident Detection, Hierarchy and Allocation
DLI
:
Département Logistique Industrielle. Industrial Logistics Department
DPLI
:
Direction de la Production et de la Logistique Industrielle. Industrial Production and Logistics Department
GFE
:
Groupe Fonction Elémentaire. Development Team
RPI
:
Risk Priority Index.
K‰
:
Cases per thousand.
LUQ
:
Liste Unique Qualité. Quality Reference List
PDCA
:
Plan, Do, Check, Act.
PIMOL
:
Panne Immobilisante. Off-road Vehicle Breakdown
RO
:
Réalisation d'Outillage. Tooling Definition
ROP
:
Réalisation d'Outillage Programme. Programme Tooling Definition
SdF
:
Sûreté de Fonctionnement. Operating Dependabiity
S‰
:
Résultat d'enquête Sofres. Sofres Survey Result
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RENAULT
1.
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FIELD OF APPLICATION Failure Modes, their Effects and Criticality Analysis (FMECA) is a product reliability preventive analysis method used to determine and correct failures on a system and/or item. the FMECA is applicable: -
-
-
to the AUTOMOBILE PRODUCT during its development phase at the Engineering Centre, Production Department and Process Department and whenever the Product or Production Process is modified. to the PRODUCTION FACILITIES during the facility design phase. to physical FLOW and information faciliti es during the operating mode development phase.
For each stage, Quality rule Q00 41 C: "Vehicle Project Milestones", indicates the intermediary objectives to be achieved f or the various types of FMECA: -
-
-
status of FMECA studies, results obtained, knowledge transfer of analyses,
in coherency with the PRODUCT/PROCESS pair development. In the project context, the FMECA status and the results obtained are determinative items used by the Quality Department for the purposes of NOTIFICATION and APPROVAL. It is the responsibility of the Operational Departments and Suppliers to adhere to this standard.
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2.
DEFINITIONS FMECA Failure Modes, their Effects and Criticality Analysis is a rigorous and preventive method aimed at determining, then in evaluating the potential failures on a system and/or item. The investigation results in the grading of such failures in order to take a decision on what measures should be taken. A follow-up chart and schedule for the implementation of such corrective actions is defined. Application of the corrective measures is checked in the field. Each study is the subject of knowledge transfer to be used as a diagnostic support and for the benefit of future projects.
PRODUCT FMECA The object of this analysis is the design and definition of the automobile product, which is examined during its development stages, prior to Tooling Go-Ahead, to ensure that the technological solution chosen meets the quantified performance specifications and industrial constraints. Potential failures have consequences for the motorist and/or his/her environment.
PROCESS FMECA The object of the analysis is the design of the industrial production process (manufacturing and control) of the automobile product, which is examined during the various envisaged production operations: manufacture, control, handling, etc., irrespective of the technology used, in order to ensure that the industrial process under study will enable the volume production of a product in accordance with the requirements specified on the drawings. The improvement may concern the product, the process or both. Potential failures may have consequences for the motorist and/or his/her environment.
PRODUCTION FACILITY FMECA The object of the analysis is the production tool, machine, robot, machining assembly, tooling, etc., which is examined during its design, to ensure that, during operation, it will satisfy the objectives of availability, product conformity and safety required in the specifications of the facility. Potential failures have consequences for the facility user, i.e. the automobile product manufacturer.
NOTE:
The production facility FMECA is conducted in accordance with CNOMO standard E41.50.530.N. It is not detailed in this standard.
FLOW FMECA The object of this analysis is the physical flow of the product, its packaging and the flow of information relative to the operation and utilisation of an installation. Potential failures have consequences for the Manufacturer and/or Operator and for the Industrial Logistics Department.
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3.
BASIC PRINCIPLE 1)
THE FMECA CAN BE USED BY ALL TO PROMOTE QUALITY AND RELIABILITY BY ADOPTING PREVENTIVE MEASURES TO MEET THE REQUIREMENTS OF THE AUTOMOBILE CUSTOMER In the context of Customer-Supplier relations, we all have a task to accomplish, whether individually or as a group: .
.
To accomplish this task "n", we need to avail of quantified input data emanating from the Supplier responsible for task "n -1". As an output, we must supply results conforming to the objective in order to satisfy our direct Customer, who is then charged with accomplishing task "n+1".
The FMECA is a quality and reliability promotion tool that contributes to the accomplishment of task "n". By its very implementation, it serves to validate its own designated task or to optimize such a task before handover to the direct Customer (figure 1).
Added value
Task n
Task n-1 INPUT
F M E C A
Task n+1 TASK
optimize
Figure 1 - Validating the specific task by working in a preventive manner on potential risks
Each task in this chain of requirements are also examined with a view to satisfying the endCustomer, i.e. the motorist. FMECA studies are scheduled to ensure they are completed before the key project decision dates.
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RENAULT 2)
"IMAGINING NEGATIVELY": 3 steps (figure 2) Step 1: The design of a product or service is always conducted in a positive manner. A service is provided to a customer in order to satisfy such customer. This service is then broken down into technical solutions, components, characteristics to ensure that the whole is operational and pleasing to the customer. Step 2: The FMECA draws on our critical faculties to form the most negative scenario possible: "what could happen to prevent this service being ensured and to what extent will the Customer be affected?" We then list the potential causes of failure liable to prevent the service being ensured. Step 3: The FMECA procedure is in no way just a simple critical evaluation of the product or process. Its main advantage is that it focuses on the search for corrective solutions in order to optimize product and production design in a predictive manner.
1
Design in positive manner
2
Imagine failures
3
Correct potential failures
1
Positive
2
Negative
3
Figure 2 3)
THE EFFICIENCY OF THE FMECA SYSTEM IS BASED ON 3 QUALITIES: COMPETENCE, CREATIVITY AND RIGOUR Competence and creativity are cultivated through the exploration of the subject in question within the framework of a multi-disciplinary working group, the members of which share their respective experience and skills in order to promote the creativity necessary to determine potential failures, however unlikely their occurrence. Rigour is developed by the methodical and full implementation of the whole FMECA procedure subdivided into 7 steps (see figure 3 below).
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SIGNIFICATION - Scope -
STEPS
Formalise the subject on a synthesis sheet indicating :
1 - INITIALIZE
- the choice of subject and its limits, - membership of the group,
1
- schedule,
WHO
- Coordinator - Requester - Decision maker - Engineering Dept (RENAULT, Partner or Supplier)
- result follow-up.
2 - ANALYSE 2 3 -EVALUATE
3
DECIDE
RESULT 4 - SEARCH FOR
4
- Present the FMECA and the functional analysis of requirement. - Imagine potential failures and their consequences for the customer using the analysis sheet - Evaluate and grade the potential failures according to predefined scales. - Decide to implement action plans for RPIs that are above the threshold.
Search for corrective solutions. This action is conducted outside the FMECA group
- Multi-disciplinary group and coordinator
- Multi-disciplinary group and coordinator
- Product and/or process designer
SOLUTIONS
5
5 - FOLLOW-UPAnalyse and evaluate the corrective solutions until the RPIs drop below the thresholds
- Multi-disciplinary group and coordinator
Apply the corrective solutions selected. This action is conducted outside the FMECA group on the ground
- Action pilot (GFE, designer ...) RENAULT internal or external
Check the efficiency of the measures taken
- Coordinator - Requester - Multi-disciplinary group
RESULT 6 -APPLY 6
7 - CHECK 7
Close the FMECA(signature).
KNOWLEDGE TRANSFER
Transfer knowledge by archiving the study in a database.
- Coordinator/Requester
RESULT
Figure 3
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4.
DETAILED PROCEDURE FMECA implementation consists in methodically following the procedure in 7 steps, an approach conducive to exhaustively determining what the potential failures are and how they might be prevented. Each step is described below.
4.1.
STEP 1: INITIALIZATION
Initialization consists in "revealing the problem", then in managing it over time. This first step is crucial for the ultimate success of the study. It is formalized through the completion of the synthesis sheet (annex 1).
4.1.1.
Selecting the subjects to be dealt with
Systematic implementation of the FMECA is conducive to validating what has already been mastered, thereby avoiding unnecessary expenditure for the Company. On the other hand, wherever there is a hint or certainty of risk, innovations, lack of knowledge or major stakes for the Company, the FMECA procedure should be deployed and focused on the priorities. Exploit and enrich existing FMECAs on similar subjects.
The project manager (vehicle, system, component, production facility, etc.) and the Quality Manager determine which subjects are at risk once the main general design and production principles have been defined (figure 4 and annex 2).
Identify all subjects with potential risks : recurrent problem
carryover item
innovative item
local risk
Process feedback Single Quality List (LUQ)
FMECA according to risk
Operating dependability + FMECA
FMECA
Figure 4 - Subject choice principle
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4.1.2.
Organizing the FMECA study
The party requesting the study (project manager or task "n" manager), internal or external to RENAULT and the FMECA coordinator must complete the "synthesis sheet", which serves as a contract between the requester and the group; it comprises: -
-
-
-
-
-
The type of FMECA (product, process, flow, etc.). The vehicle, component, scope of the study and key dates: request, tooling definition, quality milestone, volume production. The objective (K ‰, S ‰, PIMOL, durability, target non-conformity rate, etc.) and the motive behind the study (see annex 1). The name of the requester (subject manager) and of the decision maker (critical choice and decision maker). The field of application (product, process references, etc.). The membership of the group (5 to 6 persons): .
.
-
-
-
-
1 FMECA-trained coordinator. Participants (Engineering Centre, Process Department, Manufacturing Department, etc.) skilled on and responsible for the subject (indicate function).
The FMECA schedule in 7 steps according to the project milestone date. The result indicating the resolution of the potential risks. The location where the FMECA is archived, while in progress and once completed. The status of the study according to: .
.
.
the schedule, the clearance of potential risks (step 5), the verification of the results (step 7).
It is the responsibility of the requester to manage the FMECA. S/he shall sign the synthesis sheet in order to close the provisional study. -
4 key-points: a project-related product and process FMECA is conducted according to the PDCA cycle. the 4 key-points are scheduled by the FMECA study requester according to the project milestone dates (figure 5).
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RENAULT Contract
P
Tooling
D
AMPPP3
Volume Production
C
A
Figure 5 P
The product and process FMECA subjects are identified (step 1 - initialiser).
D
Potential failures are analysed and evaluated; RPIs over the threshold are the subject of an action plan and the curative actions are validated (steps 2, 3, 4, 5 and 6).
C
The identified risks are cleared for the ROP. The necessary confirmations are performed for the AMPPP3 (step 7).
A
A loop is made to bridge the gap between the potential failures cleared during the FMECA and the proven failures liable to be noticed in after-sales. The objective is to improve the efficiency of the FMECA process
4.2.
STEP 2: ANALYSING
Analysis consists in investigating the conceivable high-risk points identified as such through experience. This search is always structured according to a functional analysis.
4.2.1.
Preparing the FMECA
The purpose of this initial phase is to enable the working group to achieve the same level of knowledge of the subject and to prompt the specialists to discuss the same subject. The functional analysis comprises (see annex 3): -
the functional analysis of the requirement in order to list, characterize and grade all service functions of the system to be studied, together with the life cycle phases. The functional analysis of the requirement (stated in the functional specifications) is an FMECA prerequisite. The FMECA group extracts the items necessary for the estimated risk study. These items are adjoined with the FMECA study.
-
-
technical functional analysis used to explain the operational aspect of the envisaged solution, its organisation for all life cycle phases studied. This analysis is displayed in the form of block diagrams. The operating conditions, qualified and quantified, are listed. The block diagram is a product of the design phase or is drawn up by the FMECA group. the description of the industrial process envisaged for the volume manufacture of the product. The industrial process is defined in a manufacturing and control plan. The technical sheets and the description of the operating mode are used as input data. These data are displayed on a process diagram (or synoptic diagram, or flow chart). The input and output conditions (Customer-Supplier relation) are established.
The implementation of a functional analysis is mandatory to enable the members of the group to avail of an identical vision of the subject and reveal the exhaustive list of effects, modes, causes of potential failures together with the envisaged detection methods.
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4.2.2.
Identifying potential failures
The purpose of this second phase is to highlight the potential failures, whether conceivable or known, on the system under study. The failures are indicated in the form of qualitative and quantitative criteria as follows:
Potential failure mode: The potential failure mode: this is the manner in which the system stop operating or operate abnormally.
Potential failure modes are apprehended in the following manner: -
-
-
-
-
The operation no longer exists. The operation no longer stops. The operation is disturbed (totally, partially over time). The operation is untimely. The operation ...
Notes: the potential failure mode is expressed in physical terms: -
-
The potential failure mode is the product of the operating conditions (block diagram included). The potential failure mode shall be completed, whenever possible, by quantified criteria.
Potential cause of failure: The potential cause of failure is an initial anomaly liable to prompt the potential f ailure mode.
Failure mode
Manner in which the system does not function
© RENAULT 2000
Failure CAUSE
• initial
cause - causal chain - . . .. . .. . - . . .. . .. .
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RENAULT Notes: -
during the product FMECA: .
.
.
-
for each potential failure mode, seek the product characteristic or characteristics at the source of the potential failure (explore: the material, geometry, dimensioning, etc.). To imagine the causes, systematically explore all bodies and contacts in the block diagram). For a potential failure mode, imagine 5 to 7 potential causes.
during the process FMECA: .
.
Imagine the product-cause (characteristic of non-conforming product) liable to generate the potential failure mode. Then search for the causal chain relative to the process causes, i.e. "which process parameters are liable to prompt the product-cause". For a product-cause, imagine 5 to 7 process-causes.
Effect of potential failure: During the product and process FMECA: The effect of the potential f ailure is defined by 2 parameters: -
-
on the one hand, it is relative to a disturbed service function , on the other, it represents dissatisfaction of the automobile customer .
It is the potential failure mode that creates the disturbed function.
EFFECT of potential failure Consequence for the customer Dissatisfaction of automobile customer
Service function disturbed
mode
Service function disturbed: Manner in which the system does not operate totally .
.
.
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Potential failure
partially ...
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RENAULT Notes: -
-
Disturbed functions are expressed according to the potential failure mode and the functional analysis of the requirement. To exhaust all possibilities, imagine: .
.
.
.
.
.
-
there is no service function, there is a loss of service function, there is untimely activation of the service function, the service function is downgraded (with time, mileage, etc.), the service function is poorly interpreted, ...
For the product and process FMECA, the consequences for the automobile Customer are expressed according to the table in annex 5.
For the flow FMECA, the Customers are the manufacturer and the central production departments (DLI) (see annex 6).
Detection: Detection is the system envisaged to prevent the potential failure cause (and/or potential failure mode), that has supposedly occurred, from reaching the Customer. During the product and process, the relevant Customer is Customer (n + 1). During the flow FMECA, the Customers are the manufacturer and the Industrial Logistics Department.
Potential failure MODE Manner in which the system does not operate
Potential failure CAUSE •
Initial cause: causal chain ....... ....... -
-
-
DETECTION What has been envisaged to prevent the initial f ailure cause (and/or potential mode) from reaching Customer Client n + 1.
Notes: -
-
-
-
Under the column "detection", enter the envisaged detections (and not those to be anticipated). Give priority to "theoretical" detections (calculations, chains of dimensions, digital simulations and reinstallations, reviews, etc.) as opposed to "physical" detections (prototypes, test benches, vehicle tests, manufacturing quality control, non-assemblability, etc.). Indicate, as much as possible, the envisaged detections (qualify and quantify the parameters). During the product and process FMECA, for economic reasons, the relevant Customer (Customer n + 1) is the customer who comes immediately after the analysed activity.
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RENAULT Analysis grille: This is used to record:
the references of the subject, the names of the analysts, the dates of analysis, evaluation and follow-up.
-
The aspects of the subject to be dealt with.
-
The list of potential failures and the detections envisaged.
-
NOTE:
The grille is on paper format (A3) or electronic format (see annex 4).
Synthesis
Client satisfait
Design = "Create positively" Service to be ensured: Functions
Technical solution Operation
Service not endured
Solution malfunction
Customer dissatisfied
Potential failure mode
EFFET potentiel de défaillance
Components : Characteristics (to be specified to be manufactured Components : Characteristics inadapted or not in conformity Potential failure cause
FMECA = "Imagine negatively"
4.3.
STEP 3: EVALUATING - DECIDING
Evaluation consists in quantifying the potential failures and the envisaged detection in order to assist the requester, decision maker and those participating in the study, to define the high-priority corrective actions. Evaluation is performed once the whole analysis is complete. A scale establishes the limits defining which risk is acceptable and which is not.
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4.3.1.
Evaluation principle
The quantification is based on the chain of events leading to the perception of a failure by the Customer and to the consequences for such customer (see figure 5). For a potential failure cause to effectively bring about a given potential failure mode at the end Customer's, 3 conditions must be met: 1.
The potential failure cause is assumed to be present. At this event, a probability P1 may be assigned.
2.
If the potential failure cause is assumed to be present, it must lead to the potential failure mode considered. The probability assigned to this event is a conditional probability indicated as P2/1.
3.
If the potential failure cause-mode is assumed to be present, to reach Customer n + 1, it must pass the envisaged detections. The probability of non-detection is called P3. If P is the probability of reaching the end Customer, then: P = P1 x P2/1 x P3
P1
CAUSE
P2/1
MODE
DETECTION
P3 EFFECT (end customer)
CUSTOMER n+ 1
Figure 5 - Chain of events
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4.3.2.
Rating degrees
The rating is based on 3 degrees and on pre-established scales, i.e.
Gravity degree G: this is the evaluation of the effect of each potential failure as perceived by the end-customer.
-
Frequency degree F: is defined according to a pre-established scale and corresponds to the product of P1 x P2/1. In assigning the frequency degree, these 2 probabilities should be taken into account.
-
Non-detection degree D: is defined according to a pre-established scale and corresponds to P3.
-
Scales: product and process FMECA: the rating varies from 1 to 10 (annex 5).
-
flux FMECA: the rating varies from 1 to 4 for F and D and from 1 to 5 pour G (annex 6).
-
4.3.3.
Criticality calculation
With each association of "potential failure effect, potential failure mode, potential failure cause and detection", calculate the product of the 3 degrees: gravity, frequency, non-detection. The result is the R isk P riority I ndex, otherwise known as criticality index.
RPI = G x F x D. The evaluation is estimated by the members of the group according to databases and, by default, their knowledge and experience. Probabilities P1, P2/1, P3, the rating degrees and the RPI are recorded and preserved on analysis sheets.
4.3.4.
Hierarchy grading
To obtain an overall image of the risk on the system studied, the RPIs are illustrated in the form of a histogram. This illustration facilitates the monitoring of improvements later on.
Product and process FMECA
Flow FMECA Gravity G
GRAVITY G
1à 4
1à 7 8 et 9
CORRECTIVE ACTIONS
CORRECTIVE ACTIONS
5
IPR
10 1
10
50
100
1000 RPI
1
80
THSH THSH THSH
16
5 Thresh
Thresh
Figure 6 © RENAULT 2000
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4.3.5.
Deciding which are the priority corrective actions
The purpose of this decision is to implement all resources in order to: attain the quality - reliability - durability objective (refer to the FMECA initialization sheet),
-
optimize the quality achievement cost.
-
Decision in terms of objective: Corrective actions are undertaken for all RPIs that overstep a previously fixed limit.
FMECA TYPE
CORRECT IVE ACT ION TO BE UNDERTAKEN FOR:
Product and process
Flow
RPI > 10
if G = 10
RPI > 50
if G = 8 and 9
RPI ≥ 100
if G = 1 to 7
RPI > 5
if G = 5
RPI > 16
if G = 1 to 4
Important: It is the responsibility of the FMECA requester to define the thresholds for his/her own study by reference to: the standard,
-
quality - reliability - durability objectives of the project (without such, the standard is applied).
-
A reduction in the RPI may be obtained by focusing on the F
PROBABILITY DEGREE
× D
product factors.
FMECA
product and process
flow
It is not possible act directly on the It is not possible to act directly on Customer the consequences for the automobile (manufacturer and central production Customer department)
G
FOCUS ON THE FREQUENCY: F
P1 P2/1 P1 and P2/1
D
© RENAULT 2000
P3
-
-
-
Reduce failure causes (act on the product definition and/or industrial process). Reinforce product robustness. Combine the 2 actions.
Improve or implement a detection (watch out for cost !).
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RENAULT Optimizing quality achievement costs : At this stage of the FMECA, the cost objective is handled in 2 ways: -
-
Reduce the costs of excess quality. Between 2 solutions with the same level of estimated quality, opt for the least costly by taking into account expenditure and processing.
For all corrective actions decided upon, draw up a formalized plan on the analysis sheet: -
-
Enter the measures recommended to reduce the RPI (focus on P 1 and/or P2/1 and/or P 3). Enter the name of the action manager (department) and the date of presentation of the proposed corrective solution.
Important point: The revaluation of the RPI should not be performed at this stage but at step 5. Action plan Recommended measure
4.4.
Manager Department Lead-time
STEP 4: FINDING SOLUTIONS
The search for corrective solutions is usually conducted outside the FMECA group. The corrective solutions should be defined and formalized (modified drawing, manufacturing process modified, adjoining test result, etc.) before being submitted to the FMECA group at step 5.
NOTE:
The FMECA requester shall authorize and support the search for corrective solutions.
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4.5.
STEP 5: FOLLOW-UP
Follow-up consists in analysing and evaluation, as above (§ 4.2. and 4.3.), the corrective solutions proposed (figure 6).
Search for corrective solutions step 4
Follow-up date
Present corrective solutions Analyse potential failures (complete or review analysis table)
Evaluate new items Eliminate obsolete probabilities and degrees and add new degrees and probabilities
Adjust the indicators
RPI
> threshold
< threshold Step 6
Figure 6 - Procedure This potential failure correction stage is continued until all RPIs at risk drop below the established thresholds (figure 7). RPI number > threshold
calender initial status
check 1 check n milestone date
Figure 7 - Resolution curve IMPORTANT: The follow-up of corrective actions is crucial for the success of this analysis tool. It is the responsibility of the study requester to ensure that the FMECA advances through the progress schedule and that the risks are cleared.
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4.6.
STEP 6: APPLICATION
The corrective solutions, validated during follow-up, are implemented. Examples: -
-
-
-
-
-
-
-
specification of a new technical solution, implementation of the definition modification, validation of a calculation result, simulation, validation of a test result, modification of a manufacturing plan, procedure, tooling, etc., specification of a provisional surveillance plan, modification of operating and processing modes, ...
E
M
C C
F A
C
Before Highlighting of potential failures
F M E C A
and after correction Application of corrective measures and development of a product in conformity with expectations
Figure 8
4.7.
STEP 7: VERIFICATION - KNOWLEDGE TRANSFER
4.7.1.
Verification principle
Verification serves to achieve the objectives defined upon drawing up the "synthesis sheet". It is conducted in two stages: 1 - At the milestone date, to ensure that the corrective actions are in place and effective. 2 - During volume production, to estimate the efficiency of the FMECA study with respect to proven failures during manufacture and in after-sales.
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4.7.1.1.
Milestone date verification
Depending on the results, a decision is taken on the subsequent measures to be taken on the project in question (figure 9).
CHECK step 7
EFFICIENT SOLUTION
no
RESULT TRANSMITABLE TO CUSTOMER n + 1
RESULT NOT TRANSMITABLE TO CUSTOMER n + 1
ACTION PLAN
Projrct continuation
Figure 9 - Decision making
The members of the FMECA group, on the basis of the development file: -
-
formally check that the corrective solutions are in place, confirm by measurement, whenever possible, the hypotheses selected for the predicted evaluation.
For example: implementation of facility capability test to determine the real P1 level, verification of the accuracy of a chain of dimensions and related calculations, verification of the throughput time, work in process, etc.).
NOTE:
The FMECA is the property of the group, each member of which shall respect the undertakings and each modification to the FMECA file shall be the subject of concerted consultation.
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The v erification is conducted before the project decision milestone date, or, before the date of transfer of task "n" to the internal Customer(n + 1). The verification result is co-signed in a result note adjoined to the FMECA file. It constitutes a Quality Assurance File item. The study requester decides on the termination of the FMECA by signing the synthesis sheet.
4.7.1.2. -
Verification during volume production
During manufacture: the FMECA file is used to define part of the process audit reference system. On the one hand, it is used to check the continuity of corrective actions and, on the other, the efficiency of the FMECA study by comparing the potential failures with the real failures in the process.
-
During after-sales: by comparing the proven failures in after-sales (DDHA list) and the potential failures as imagined during the FMECA study, it is possible to judge the efficiency of the study. For a system subject to an FMECA study, during volume production, there should be no failure beyond the company quality - reliability objectives (as a priority, check that G = 8, 9 and 10). Otherwise, it is necessary to seek the cause of the FMECA non-efficiency and to remedy such, for example by: .
.
.
4.7.2.
the further training of the coordinator, optimize the content of the FMECA standard, make the Quality Assurance acknowledgement indicators more stringent.
Knowledge transfer
The content of the FMECA is a written memory for the Company: -
-
-
-
to be used in future projects (as such or as a complement), during the process audit at the operating phase, upon changes to the product or process (phase II, production centre demultiplication, etc.), in the event of a dispute between the Customer and Supplier, or for legal purposes.
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Accordingly, a file shall be compiled and archived in paper or electronic form, comprising:
FMECA product
process
flow
X
X
X
specification or its reference,
X
X
drawings, diagrams or their references,
X
X
manufacturing plan or its reference,
X
X
The synthesis sheet. The information on the subject under study and the modifications: -
-
-
-
X
operating and processing modes.
The functional analysis: -
-
-
-
function investigation,
X
X
block diagram,
X
X
X
X
process chart,
X
flowchart.
The analysis, evaluation and corrective action sheets.
X
X
X
The result notes.
X
X
X
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ANNEX 1 SYNTHESIS SHEET (FORMAT A4) Product FMECA Process FMECA
FMECA SYNTHESIS SHEET
Other FMECA: Vehicle:
Date of request:
Component:
Milestone date: Volume production date:
Scope: Objectives of the study:
Causes of the study:
REQUESTER: M.
Dept.
DECISION MAKER: M.
Dept
Limits of study:
PARTICIPANTS: Permanent MM.
Temporary Dept. and function
MM.
Dept. and function
COORDINATOR: M. P L A N N I N G
Weeks Forecast Finished Legend
Meeting: R
Follow-up: S
Verification: V
steps 2 and 3
step 5
step 7
Initial B I L A N
Dept.
Date: TOTAL G = 10, Nbr RPI > 10 G = 8 and 9, of RPI RPI > 50 G de 1 to 7, RPI ≥ 100
Follow-up
Milestone date: J
Nbre d'IPR ≥ seuil
dates initial
suivi
suivi
jalon
Archival location:
Decision at end of study : potential risks have been cleared.
Date: Signature of requester:
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ANNEX 2 CHOOSING THE SUBJECTS TO BE DEALT WITH FOR THE PRODUCT FMECA
Système system complexe : boîtier papillon motorisé, -- Complex : motor-driven throttle unit, siège à mémoire, memory seat, ... ... Multitechnologique : prétentionneur : -- Multi-technology: pretensioner mécanique + électronnique + ... (mechanical +electronic + ...) Complexité Product du produit : complexity
- Simple system : door closing mechanism, ... - Simplified technology: plastic injection and metallic insert, ... - Mono-technology : stamping, painting, ...
Carryover known failure. Different environment Reconduit without sans défaillance connue. Environnement or ouoperating conditionsconditions. d'utilisation différents. Carryover greater than objective Reconduit with avecfailures défaillances supérieures à l'objectif or oufailures défaillances unknown. inconnues. Productou or Produit technical solution solution : technique
New Contrainte constraint or nouvelle carryover ou reconduite :
Concepteur Product dudesigner produit :
Modified
Product FMECA on product compatibility with new data Use feedback (LUQ) and/or product FMECA Product FMECA relative to modifications Operating dependability then product FMECA
Innovative (keyless vehicle)
Operating dependability then product FMECA
Regulations
Product FMECA
Safety
Product FMECA
New supplier or supplier with partial experience of product
Product FMECA
List of proven failures (after-sailes) and or quality (LUQ)
Existing product FMECA
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Product FMECA
New
Multi-disciplinary suppliers
Feedback
Operting dependability study then product FMECA on functions or subsystems with serious undesirable incident
Operating dependability then product FMECA Process feedback
To be confirmed or completed for product carryover
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ANNEX 2 (continued) CHOOSING THE SUBJECTS TO BE DEALT WITH FOR THE PROCESS FMECA
- Multi-technology process : stamping + bodywork + painting + fitting, ... Process complexity - Process with simplistic technology : assembly, welding, ... - Full part development process
Carryover without known failure. Different environment or operating conditions. Carryover with failures greater than objective or unknown failures. Process or technical solution
Process designer
Modified
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Process FMECA
Process FMECA on product compatibility with new data Use feedback (quality) and/or process FMECA process FMECA relative to modifications
New
Operating dependability then process FMECA
Innovative (laser welding)
Operating dependability then process FMECA
New supplier or supplier with partial experience of process Multi-technology suppliers
Feedback
Operating dependability then process FMECA on functions or subsystems subject to serious undesirable event
Existing process FMECA
Process FMECA
Operating dependability then process FMECA
To be confirmed or completed for carryover processes
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ANNEX 2 (continued) CHOOSING THE SUBJECTS TO BE DEALT WITH FOR THE FLOW FMECA
CONDITION
F L U X
CONDUCTING A FLOW PERFORMANCES (volume to FMECA be produced, production sequence, product conformity) Decision Objective Known and on target
NO
Unknown
YES
Improve the envisaged operating or processing mode.
New operating or processing mode
YES
Validate the envisaged operating or processing mode.
Modified mode
YES
Analyse the modified part.
Mode with risks of a production blockage
YES
Analyse the potential risk part.
Carryover of an existing operating or processing mode (for a vehicle, future component or new installation)
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ANNEX 3 LIST OF BASIC DATA AND FUNCTIONAL ANALYSIS TO BE CONDUCTED PER TYPE OF FMECA
INPUT DATA
FMECA
TYPE OF ANALYSIS TO BE USED PRODUCT
PROCESS
YES
YES
YES
YES
Functional analysis of requirements (utilisation function, Performance or adaptation function, estimation, functional specifications constraint function and value criteria) Drawings of systems studied Plans: -manufacturing - control - ... with references Operating and processing mode
Functional analysis of design (block diagram) Process diagram (or manufacturing and control flowchart)
Functional analysis of flow
FLOW
YES
YES
and Use existing flow diagram or if non-existent plot one
YES
There shall be as many block diagrams as there are different life cycle phases for the subject
studied. As a rule, one or two block diagrams generally suffice to determine the product operation.
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ANNEX 4 PRESENTATION OF THE ANALYSIS GRILLE Product FMECA, process FMECA and flow FMECA (format A3)
Failure Modes, their Effects and Criticality Analysis Component ..........
1
Vehicle ..........
FMECA
N°
Dates
Potential failure
and/or
Effect
process Customer
Disturbed function
consequence
6
14 3
2
References: Function
Analysts:
7
8
4
5
Action plan
Mode
Cause
(P2/1)
(P1)
9
10
Detection G F D (P3)
11
I RecommP R ended
Mngr
Result
measures Time Measure taken
12
13 14
15
14
16
Legend: 1:
Product designation.
2:
Specify: product, process or flow FMECA.
3:
Name of FMECA participants and coordinator.
4:
Dates of document origin and modifications.
5: Page No.. 6:
No. used as a line marker for each potential failure cause.
7:
Functions studied (product) or manufacturing operation descriptions (process), flow management points.
8:
Disturbed function and consequences for the customer.
11: Indicate the provisions taken to prevent the cause (and/or mode) that has supposedly occurred, to reach customer n+1. Also indicate in this column, the probability v alue P 3. 12: Calculate the level of criticality (RPI) by reference to the scales: G: gravity degree according to gravity scale. F: frequency degree according to scale and probability product P1 x P2/1. D: non-detection degree according to probability degree P 3 RPI = G x F x D
13: Indicate the measures envisaged to reduce the RPI (adjust P1 and/or P2/1 and/or P3). 9: The potential failure mode indicates the manner in which the system does not operate. 14: Name of action manager and time to present Also enter in this column the probability value: P proposed corrective solution. 2/1. 15: Record the corrective measure presented upon 10: The potential cause of failure relative to the analysis and evaluation (stage 5). product is the initial anomaly that generated the 16: Calculate the new RPI after analysis and potential failure mode. The causal chain, is the evaluation of the corrective solution proposed. string of events that preceded the appearance of the cause-product. Also enter in this column, the probability value: P 1.
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ANNEX 5 RATING SCALES
Product and Process FMECA - Gravity degree(G)
G
Consequences for the motorist
Service function disturbed
The customer is not capable of detecting this potential failure.
The minimal nature of the disturbed service function does not cause any perceptible effect with regard to the performance of the vehicle or its equipment.
2-3
The potential failure constitutes a slight inconvenience for the customer.
The minimal nature of the disturbed service function does not cause and notable interference with the performance of the vehicle or its equipment.
4-5
The potential failure upsets or disturbs the.
The disturbed service function, with preincident signs, causes a slight degradation to the performance of the vehicle or its equipment
6-7
The potential failure displeases the customer. Repair costs are moderate.
The disturbed service function, without any pre-incident signs, causes notable degradation to the performance of the vehicle or its equipment.
8
The potential failure greatly annoys the customer. Repair costs are higher .
The disturbed service function, with or without pre-incident signs, causes the loss of a function, without necessarily putting the vehicle off the road.
9
The potential failure is a major grievance for the customer: off-the-road breakdown.
The disturbed causes a vehicle off-road breakdown.
10
The disturbed function causes a potential failure relative to safety or a failure out-ofconformity with applicable regulations .
1
Notes: -
-
-
-
If in doubt when choosing between 2 degrees, the FMECA group will always opt for the higher degree. G = 10 is exclusively reserved to potential failures with an impact on safety or regulations. G = 9 is exclusively reserved to potential failures causing a vehicle off-road breakdown (ex: battery failure, etc). G = 8 is reserved for potential failures causing high repair costs .
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ANNEX 5 (continued) RATING SCALES (continued)
Scales used in the product and process FMECA
F
PROBABILITY OF OCCURRENCE P1 x P2/1
1
[
0
to 3/100 000
2
[
3/100 000 to
3
[
1/10 000
4
[
5
D
PROBABILITY OF REACHING CUSTOMER N+1: P3
[
1
[
0
to
1%
[
1/10 000
[
2
[
1%
to
4%
[
to
3/10 000
[
3
[
4%
to
9%
[
3/10 000
to
1/1 000
[
4
[
9%
to
16 %
[
[
1/1 000
to
3/1 000
[
5
[
16 %
to
25 %
[
6
[
3/1 000
to
1/100
[
6
[
25 %
to
36 %
[
7
[
1/100
to
3/100
[
7
[
36 %
to
49 %
[
8
[
3/100
to
10/100
[
8
[
49 %
to
64 %
[
9
[
10/100
to
30/100
[
9
[
64 %
to
81 %
[
10
[
30/100
to
100 %
]
10
[
81 %
to
100 %
]
Note: During the product FMECA, it is sometimes more difficult to estimate P 1 and P3, in which case the designer may use the qualitative scale below:
Qualitative scales that can be used during the product FMECA
F
EVALUATION CRITERIA
D
EVALUATION CRITERIA
1
Characteristics and solutions already upgraded, same environment and same utilisation.
1
Validation on vehicle (5 x 150 000 km) and endurance test followed by a component analysis.
3
Characteristics and solutions already upgraded, however environment and utilisation different.
3
Test on bench and/or vehicle.
5
Characteristic defined on drawing, however reliability not proven.
5
Chains of dimensions and calculations, digital simulation, dimensioning calculations, mock-up, ...
7
A volume production reference exists, however it is poorly defined or not known.
7
Reinstallation (at nominal, digital), drawing review, ...
10
Characteristic not defined on drawing, or not known or interpretable.
10
Without detection or what is envisaged is inefficient.
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ANNEX 6 RATING SCALES
Flow FMECA Gravity degree (G)
G
Consequences for users Product
et/ou
In conformity
Volume
Order
et/ou
1
Without consequence
In conformity
In conformity
2
Inconvenienced
Non conforming rework on line
Small loss of volume (1)
3
Unhappy
Non conforming rework off line
Medium loss of volume (1) Order moderately disturbed (vehicle cycling indicator(1))
4
Very unhappy
The non-conformity reaches the internal customer
High loss of volume (1)
5
Catastrophic
The non-conformity may reach the automobile customer
Order slightly disturbed (vehicle cycling indicator (1))
Order highly disturbed (vehicle cycling indicator(1))
Production stoppage
(1) The % of volume loss and cycling are defined at the beginning of the FMECA in conjunction with the manufacturer and the Central Production Department (DPLI).
Frequency degree (F)
F
Occurrence probability (P1 x P2/1) Note: in the absence of P1 and P2/1, occurrence is indicated in days.
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1
Less than once a month
2
Once a month once from [6 days to 20 days]
3
Once a week Once from [2 days to 5 days]
4
Once or n times a day
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