201002ASQ0511ProcessFailureModeEffectsAnalysis

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PFMEAProcess Failure Mode and Effects

AnalysisJames Davis, General Dynamics



Jam es Dav is, GDLS Sl id e Nu m ber : 2

Purpose

The purpose of this presentation is to

share the benefits of a detailed ProcessFlow Diagram, conducted during aProcess Failure Mode and Effects

Analysis, that will ensure productquality in the manufacturing/assemblyprocess.



Jam es Dav is, GDLS Sl id e Nu m ber : 3

Introduction




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Most COMMON Types of FMEA's

Design (Potential) Failure Modes andEffects Analysis-DFMEA• Focus is on potential design- related failures

and their causes.

Process (Potential) Failures Modes and

Effects Analysis-PFMEA

• Focuses is on potential process failures andtheir causes.



Value of FMEA's

Aids in improving designs for products andprocess Increased safety

Enhances Customer Satisfactiono Better Quality

o Higher Reliability

Contributes to cost savingsDecreases warranty costs

Decreases waste, non-value added operations



PFMEA's

Focus is on potential process –relatedfailures and their causes.Main drive is to understand the process through theidentification of as many potential failures as possible.

o e.g. Incorrect material used

PFMEA typically assumes that the design

is sound.Development of Recommended Actions is

targeted at eliminating the Root Cause ofthe potential failures.



PFMEA

Three Parts:

Process Flow Diagram (PFD)Process Failure Mode and Effects

Analysis (PFMEA)Process Control Plan (PCP)



Product Definition:Key Product Characteristics, DFMEA

Process Definition:Process Flow Diagram (PFD),

Failure Mode Analysis:PFMEA

Control Strategy:Control Plan,Error proofing

Customer Requirements:

Manufacturing:Work Instructions & Process Monitoring

Information Flow

SOR, Vehicle Tech Specs,System Technical Specs

Product and Process Characteristics

DFMEA/PFMEA I f ti


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DFMEA/PFMEA Information

Interrelationships

DFMEA

Design FMEA

Process Flow

Diagram

PFMEA

Process FMEA

Boundary (Block)

Diagram, P- Diagram,

Etc.

Design Verification

Plan & Report

(DVP&R)

Process Control

Plan


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Process Flow Diagrams

The Process FlowDiagram provides alogical (visual)depiction of theprocess that is beinganalyzed.



Jam es Dav is, GDLS Sl id e Nu m ber : 1 212

The SAE/AIAG PFMEA guidelines describe twomethods of defining process functions.

Either or both may be used.Process Functions may be described in terms of:

The product features/characteristics that arecreated

or

The process actions that are performed

Process functions should be identified in detailas necessary to provide information for the

PFMEA to develop effective Process Controls

Process Function / Requirement




Consider a simple operation to drill a hole in ametal part

The product characteristics & requirements are: Hole size: 4.00 mm +/- 0.13

Hole Location:X = 28.0 mm +/- 0.2

Y = 15.0 mm +/- 0.2

Perpendicular to surface, no burrs, etc.

The process operation must create theseproduct characteristics and meet therequirements


X

Y

4.00




To drill the correct hole size in thespecified location, the process must:

Position and hold the part Align the part fixturing

with the drill position Assure the correct drill

bit size is used Set and control drill speed Anticipate tool wear and

schedule preventive maintenance

If the Function/Requirement is defined in

the PFMEA as “Drill Hole” could any ofthese be missed?





Process Flow Diagram (PFD)

Process Flow Diagram is the foundation The process must be defined step by step, including

interfaces

The PFD provides the structure to document what productcharacteristics and requirements (OUTPUTS) are affectedby a given operation and how these characteristics andsources of variation are controlled (INPUTS)

PFD is a graphical representation of every possible path apart can take through the anticipated manufacturingprocess

A well defined PFD establishes the foundation for thePFMEA

Helps in developing equipment specifications. How will the process control non-conforming material? How and when will inspections be performed, what is

required?

How and when will parts be re-introduced into theprocess?




Process Flow Diagram (PFD)

Hidden Factories: Interfacing Processes

Quality Audits Product/tooling Changeovers

Rework Processes Part Ident./Labeling

Alternative Processes TeardownScrap Gauging Stations

Part Buffers Reject Handling

Part Movement

Interface process issues affect quality performance

o Rework and scrap parts bypass process controlso Mixed parts in the manufacturing process at changeovers

Need for common systems Part of the overall Quality Strategy must include

o Common content, common format, common approach

Quality strategy must extend to suppliers

o Considered an extension of the Total Quality processes




SAE J1739 March 2009




Micro Level PFD Example




Process Characteristics

PFD Feeds PFMEA




PFD Feeds PFMEAIdentify the Function(s)

Function is a description of what theProcess does to meet the requirements

Related to process specification and productcharacteristics

Comes from the PFD operation description column

Functions can be described as:Do this operation…

To this part or material…

With this tooling or equipment…




PFD Feeds PFMEA




Linkage to PFMEA




PFMEA Example continued..




Sources and Types of Manufacturing Variation

Source of Variation Types of Variation Typical Process Controls

OperatorOperator Skill,Ergonomic Factors

Training, instructions, visual aids, feedbacklayout, motion analysis, human factors

Component /

Material

Incoming raw material, purchased

parts, previous operations

Supplier management, internal controls, error

proofing

Equipment /Machine

Machine capability, adjustment,wear over time

Equipment specifications, closed-loopmachine controls, preventive maintenance

EnvironmentTemperature, humidity, dust, noise Climate control, air filtration, clean room,

sound insulation

Methods & Systems Sequence, procedure, layoutIndustrial Engineering techniques,Lean Flow analysis

Set Up(for stableprocesses)

Initial set up or adjustment

Process specification, first / last piece check,automated controls

ToolWear over time, breakage,tool-to-tool differences

Predictive maintenance, detection error-proofing, tooling specifications

MaintenanceRepair, replacement, reassembly,adjustment

Instructions, error-proofing, machinequalification, production trial run

Fixture / PalletPosition tolerance, adjustment,wear over time

Predictive maintenance, prevention anddetection error-proofing




PCP will be based on the previousactivities in PFD and PFMEA.

Review the PFMEA informationdeveloped & supplied and use to identify:

Specific controls that may be needed due to the

information added Identify which controls are Product or Process

o Note any Special Characteristics

o Identify evaluation methods, frequency and ControlMethods

o Note Reaction Plans (particularly related to NC parts)

Process Control Plan

Process Control Plan Example





Part/ ProcessNumber

Process Name / Operation Description

Machine,Device, Jig,

Tools for Mfg.

CharacteristicsSpecialChar.Class.

Methods

ReactionPlan

No. Product ProcessProduct / Process

Specification / Tolerance

EvaluationMeasurement

Technique

SampleControl Method

Size Frequency

300 Initiate weld sequence /

Perform TIG weld offrame parts.

Robotic Armcontroller.TIG welders.

Weld beadsper designspecification.

Tube welds meetpull test withfailure in parentmaterial.

Pull testusing testfixture 20-1.

1 pc. Per shift. Hydraulic pull testinstruction TI21-01

Process monitoringform PMF-20-01

Quarantinematerialsince lastgood pulltest.

Good welds,no visibledefects.

yes Weld appearancemeets visualstandard.

Operatorevaluation toVisual StdTB20-VS1

100% Eachpiece. Visual inspection OWI#20-01. Remove partand send torepair.

Weld voltage yes 24 Volts AC+/- 2.0 volts

MachineControl

100% Each weldcycle.

Closed-loop machinecontrol.

Scrap part &Re-startwelder.

Weld voltage yes 24 Volts AC+/- 2.0 volts

Visual Onceeach

Shift startorchange-over or

maint.event.

Set-up OWI #20-02 &Form PMF-20-02

Periodicmaintenance per PM-

WI #20.

Scrapcurrent part.Shut down.Notify

maintenance.

Inert gas flowrate

yes 5 cubic feet / min.+/- 0.5 cfm

Visual twice Per shift. Operator cleans gascup twice per shiftPM-WI-20. Processmonitoring form PMF-20-01

Notifymaintenance.

Inert gas flowrate

yes 5 cubic feet / min.+/- 0.5 cfm

Visual ofverification

of FlowMeter

Onceeach

Shift startor

change-over ormaint.event

Set-up OWI #20-02 &Form PMF-20-02.

EquipmentCalibration Procedure#368

Quarantinematerial

since lastgood pulltest.Notifymaintenance.

Form 818-1 (Rev 12Apr02)

CONTROL PLAN Control Plan No:

Part Number/Latest Change Level Key Contact/Phone Date (Orig.) Date (Rev.)

Customer Part Number CoreTeam

Customer Engineering Approval/Date (If Req'd.)

Part Name/Description Supplier/Plant Approval/Date Customer Quality Approval/Date (If Req'd.)

Supplier/Plant Supplier Code Other Approval/Date (If Req'd.) Other Approval/Date (If Req'd.)

Prototype Pre-Launch Production






Initiate weld sequence / Confirm Wire feed rate

Initiate weld sequence / Confirm Weld voltage

Initiate weld sequence / Perform TIG weld offrame parts.

Initiate weld sequence / Confirm Inert Gas flowrate

Scrap part &Re-startwelder

Closed-loop machinecontrol.

Each weldcycle.

100%MachineControl

300 mm / minute+/- 10 mm / min.

yesWeld wirefeed rate

Scrap part

& Re-startwelder

Closed-loop machine

control.

Each weld

cycle.

100%Machine

Control

24 Volts AC

+/- 2.0 volts

yesWeld voltage

Notifymaintenance.

Operator cleans gascup twice per shiftPM-WI-2500. Processmonitoring form PMF-

20-10

Per shift.twiceVisual5 cubic feet / min.+/- 0.5 cfm

yesInert gas flowrate

Removepart andsend torepair.

Visual inspection OWI#20-010.

Eachpiece.

100%Operatorevaluation toVisual StdTB20-VS1.

Weld appearancemeets visualstandard.

yesGood welds, novisible defects.

Scrap currentpart.Shut down.Notifymaintenance.

Set-up OWI #20-020 &Form PM-20-020

Predictivemaintenancepinch roller replace @180 days.

Shift startor change-over ormaint.event

100%Operatorsetup checkandverification

300 mm / minute+/- 10 mm / min.

yesWeld wirefeed rate

Quarantinematerialsince lastgood pulltest.Notifymaintenance.

Set-up OWI #20-02 &Form PM-00-02.Equipment CalibrationProcedure #368


Onceeach

Visualverification ofFlow Meter

5 cubic feet / min.+/- 0.5 cfm

yesInert gas flowrate

Scrapcurrentpart.Shut down.Notifymaintenance.

Set-up OWI #20-02 &Form PM-20-02Periodic maintenanceper PM-WI #20.


Onceeach

Visual24 Volts AC+/- 2.0 volts

yesWeld voltage

Quarantinematerialsince lastgood pulltest.

Hydraulic pull testinstruction TI41-01

Process monitoringform PM-20-010

Per shift.1 pc.Pull testusing testfixture 20-1.

Tube welds meetpull test with failurein parent material.

Weld beads perdesignspecification.

Robotic ArmTIG weldersand controllers.

300.

.

Robotic ArmTIG welders

Initiate weld sequence / Close and latch curtain

300

FrequencySize

Reaction

PlanControl Method

SampleEvaluation

MeasurementTechnique

Product / Process

Specification / Tolerance

ProcessProductNo.

MethodsSpecialChar.

Class.

CharacteristicsMachine,

Device, Jig,Tools for Mfg.

Process Name /

Operation Description

Part/ ProcessNumber

C S di S li A




Case Studies – Supplier A

Not ISO Certified, Primarily Defense business base Sole Source - Unique Technology No Process Flow

Operator work instruction for 100 piece componento 20 process steps on a single piece of paper (included machining)

o Building the component relied on Tribal Knowledge

Diagramming the Process Flow 20 steps turned into 951 steps to produce the component

22 manufacturing related issues (from DFMEA) wereincorporated in the PFD/PFMEA

Supplier A used PFD - FMEA to Develop work instructions

Determine the requirement to developed training programsfor assemblers / machinists, QC personnel

Develop safety program / training

C St di S li B




Case Studies – Supplier B

ISO Certified, Primarily Defense business base

Sole Source - Unique Design

“Fair” Documented Process Flow

Relied on a combination of operator knowing what shouldbe done next with operator work instructions.

o However it did allow for repeatable assembly of component with

skilled employee Diagramming the Process Flow

270 step PFD became 1,170 steps

o

FMEA analysis determined: work instructions that neededimprovement and new work instructions were required

Supplier B used PFD- FMEA to

Update work instructions to error proof build process

C St di S li C




Case Studies – Supplier C

ISO Certified, Defense/Civil business base

Well Documented Process Flow

Operator work instructions allowed for repeatable assembly

Error Proofing allows for assembly with “average”employees

Diagramming the Process Flow

263 step PFD became 268 steps

32 manufacturing related issues (from DFMEA) wereincorporated in the PFD/PFMEA

o FMEA analysis determined: work instructions that neededimprovement and new work instructions were required

Supplier C used PFD- FMEA to

Update work instructions

C St di S li D




Case Studies – Supplier D

ISO Certified, Aerospace business base Very Small Company

2 Master Assemblers (1 of which was the Assembly & TestManager)

Unique Technology “Fair” Documented Process Flow

Relied on a combination of operator knowing what should be done nextwith broad operator work instructions.

o However it did allow for repeatable assembly of component with highly

skilled employee Diagramming the Process Flow

5 page PFD became 22 pages

FMEA analysis determined: work instructions needed improvementto allow for production of more than 1 component at a time

Supplier D used PFD - FMEA to Develop work instructions with boundary photos Recall non-compliant parts Determine the requirement to developed training programs for

assemblers, QC personnel Develop detailed ATP




Recapping

Process Flow Diagram“What does the process do?

Control Plan“What needs to be controlled/monitored?”

“How do we react to problems?”

PFMEA“What could go wrong?”

“Could we prevent or detect?”

Operator Instructions & Monitoring“What am I supposed to do?”

“How am I supposed to do it?”“Where am I supposed to record it?”

References




References

AIAG FMEA Fourth Edition June 2008

SAE J1739 March 2009

Vocabulary




Vocabulary

AIAG FMEA Fourth Edition Published June 2008 SAE FMEA J1739 Published March 2009 PFD, Process Flow Diagram

PFMEA, Process Failure Modes and EffectsAnalysis PCP, Process Control Plan

Documents

201002ASQ0511ProcessFailureModeEffectsAnalysis