error proofing techniques

8/8/2019 Error Proofing Techniques

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ERROR

PROOFING

TECHNIQUES

SUBMITTED TO:- GAURI MADAM

BY GROUP NO:- 4


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ERROR TRACKERS

DISHA 7511ANIKET 7516

DEEPALI 7518

PRIYANKA 7522

MEGHA 7525

MAHADEV 75__ VINAY 7564


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Definition: FMEA

failure modes and effects analysis

engineering technique used to define,

identify, and eliminate known and/or

potential failures, problems, and errors

from the system, design, or process before

they reach the customer


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Causes of errorschedule pressures

oversight

lack of testingchanging requirements

lack of structure

miscommunications

lack of prototypingincomplete CR

dependence on experience

dimension error


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Incomplete:taskspecified

butnotperformed

comprehensively

Omission:task

notperformed

Inadequate:tasknotspecified

comprehensively

Incorrect:

taskasspecified

resultsinerrors

Misperformed:

taskperformed

Incorrectly+++++++


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Type of FMEA How it works/what it does

Type of FMEA How it works/what it does

System FMEA Use VOC's to assign risks to thefailure of a system function

Design FMEA Looks at components of the

system

Assembly ProcessFMEA

Looks at impact of failures ofthe

manufacturing and assembly

process on the final system

Human Error FMEA Narrows process FMEA to lookat human mistakes and

omissions

in manufacturing


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Design Process FMEA

Similarto Assembly Process FMEA

question-basedanalysis

quickeranalysis

Analyzeandimprovethe

organizations design ordevelopmentprocess rather

thanaspecificproduct

?Process can be continuously improved to optimize

performance for many products

Decomposeproblemintodesign tasks instead of

Subassemblies++


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The 4 ComponentsofZDQ

ZDQfunctionsbycombiningfourelementarycomponents:

1. PointofOriginInspection

2. 100 % Audit Checks

3. Immediate Feedback

4. Poka-Yoke


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Inspection

The3basicapproachestoinspectionofprocessedproductare:

Judgement/StandardInspection

InformativeInspection

PointofOriginInspection

Thefirsttwoapproachesarewidelyusedandconsidered

traditional.

Only PointofOriginInspectionactuallyeliminates

defects.


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Focusonprevention,notdetection.

Oneofthe 4 basicelementsofZDQ.

DiffersfromJudgementandInformative:

Catcheserrors

Givesfeedbackbeforeprocessing

Noriskofmakingmoredefectiveproduct

DetectError

Feedback/Corrective Action

Processwith Zero Defects

Bycombining Checkand Dointhe ZDQapproach;the Doingiscontrolledsoit

cannotbewrong100% ofthetime!

Mayinclude: Switchesthatdetectmiss-fedparts

Pinsthatpreventmiss-feeding

Warninglights

Soundsignals


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ZDQ/Checkand Do/PointofOrigin

Inspection


Checkforoptimumprocessconditions

beforeprocessingisdoneanderrorscanbe

made.

Instantfeedback.

Correctionsmadebeforedefectsoccur.


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100% Audit Checks

PointofOriginInspectiononeverypiece.

Thesecondofthe 4 basicelementsofZDQ.

Differsfrom SQC inspection:

Doesnotrelyonsampling

Preventsdefects

Doesnotassumedefectswillstatisticallyoccur

100% Auditcheckseverythingontheline!

Zero Defects


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Quick Feedback

Errorcorrectionassoonaspossible

Thethirdofthe 4 basicelementsofZDQ.

Differsfromtraditionalinspectionapproachesthat:

Correctproblemsaftertheprocess

Addresstheproblemwhenerrorsarealreadydefects

Insomecasesneveridentifyanerrorhasoccurred

ZDQsendstheoperatorasignalandalarmsthe

personthatanerrorhashappened!

ZDQInspections = Immediate Feedback


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Poka-yoke

Mistake-proofingsystems

Thefourthofthe 4 basicelementsofZDQ.

Doesnotrelyonoperatorscatchingmistakes

Inexpensive PointofOrigininspection

Quickfeedback100% ofthetime

The machine shut

down. We must have

made an error!

BEEP!

BEEP!

BEEP!Most Poka-yokedevicesaresensoror jigdevices

thatassure100% complianceallthetime!


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The SevenGuidelinesto Poka- Yoke Attainment

1.) Quality Processes - Design Robustqualityprocessestoachievezerodefects.

2.) UtilizeaTeamEnvironment- leveragetheteamsknowledge,experience to

enhancetheimprovementefforts.

3.) EliminationofErrors -Utilizearobustproblemsolvingmethodologytodrivedefectstowardszero.

4.) Eliminatethe Root CauseofTheErrors-Usethe5Whysand2 Hsapproach

5.) DoIt RightThe FirstTime- Utilizingresourcestoperformfunctionscorrectlythe

firsttime.

6.) EliminateNon-Value Added Decisions- Dontmakeexcuses-justdoit!

7.) ImplementanIncremental ContinualImprovement Approach-implement

improvementactionsimmediatelyandfocusonincrementalimprovements;efforts

donothavetoresultina100% improvementimmediately.


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Poka-yoke

Whatis Poke-yoke?

A method that uses sensor or other devices for catching errors

that may pass by operators or assemblers.

Poka-yokeeffectstwokeyelementsofZDQ:

Identifying the defect immediately (Point of Origin Inspection)

Quick Feedback for Corrective Action

How effective the system is depends on where it is used: Point of Origin orHow effective the system is depends on where it is used: Point of Origin or

Informative Inspection.Informative Inspection.

Poka-yokedetectsanerror,givesa

warning,andcanshutsdownthe

process.


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Twotypesoferrorproofingdevices

POKA-YOKE

Control - eliminatesthepossibilityofa

mistaketooccur (automaticmachine

shutdown)

Warning - signalsthatamistakecanoccur(blinkinglight,alarm,etc.)


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Poka-yoke

Poke-yokeand PointofOriginInspections( Proactive Approach):

A fully implemented ZDQ system requires Poka-yoke

usage at or before the inspection points during the

process.

Poka-yokewillcatchtheerrors

beforeadefectivepartis

manufactured100% ofthetime.


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SomeexamplesofPOKA-YOKEdevices

Attachedgascap

Gaspumpnozzle

Polarizedelectricalplugandsocket

Discbrakepadwarningnoise


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Poka-yoke

Poka-yokeandInformativeInspection( Reactive Approach):

Checkoccursimmediatelyaftertheprocess.

Canbeanoperatorcheckattheprocessorsuccessivecheckatthenext

process.

Not100% effective,willnoteliminatealldefects.

Effectiveinpreventingdefectsfrombeingpassedtonextprocess.

Although not as effective as the Sourceinspection approach, this methodology

is more effective than statistical

sampling and does provide feedback in

reducing defects.


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Poka-yoke SystemsGovernthe Process

Two Poka-Yoke Systemapproachesareutilizedin

manufacturingwhichleadtosuccessful ZDQ:

1. Control Approach

Shutsdowntheprocesswhenanerroroccurs.

Keepsthe suspectpartinplace

when anoperationisincomplete.

2. Warning Approach

Signalstheoperatortostoptheprocess andcorrecttheproblem.


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Control System

Takeshumanelementoutoftheequation;does not

dependonanoperatororassembler.

Hasahighcapabilityofachievingzerodefects.

Machinestopswhenanirregularityisdetected.Theremusthavebeen

anerrordetected;themachineshutdownby

itself!


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Warning System

Sometimesanautomaticshutoffsystemisnotanoption.

A warningoralarmsystemcanbeusedtogetanoperators

attention.

Belowleftisanexampleofanalarmsystemusingdials,lightsand

soundstobringattentiontotheproblem.

Colorcodingisalsoaneffectivenonautomaticoption.

BEEP!

BEEP!

BEEP!

Imgladthealarm

wentoff,nowIm

notmaking

defects!


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Methodsfor Using Poka-yoke

Poka-yokesystemsconsistofthreeprimary

methods:

1. Contact

2. Counting3.Motion-Sequence

Eachmethodcanbeusedinacontrol

systemorawarningsystem.

Eachmethodusesadifferentprocess

preventionapproachfordealingwithirregularities.


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ContactMethod

A contact method functions by detecting whether a sensing

device makes contact with a part or object within the process.

Missingcylinder;pistonfully

extendedalarmsounds

ContactMethodusinglimit

switchesidentifiesmissing

cylinder.

Anexampleof aphysicalcontact

methodislimitswitchesthatare

pressedwhencylindersaredriveninto

apiston. Theswitchesareconnected

topistonsthatholdthepartinplace.

Inthisexample,acylinderismissing

andthepartisnotreleasedtothe

nextprocess.

Cannotproceed

tonextstep.

Cylinderpresent


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Physical Contact Devices

Limit Switches

Toggle Switches


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Energy Contact Devices

Photoelectricswitchescanbe

usedwithobjectsthatare

translucentortransparent

dependingupontheneed.

Transmissionmethod:twounits,

onetotransmitlight,theotherto

receive.

Reflectingmethod:PEsensor

respondstolightreflectedfrom

objecttodetectpresence.

Light

Transmitter Receiver

Object

Ifobjectbreaksthetransmission,themachineissignaledtoshutdown.


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Contact Device

Anexampleofacontact

deviceusingalimit

switch. Inthiscasethe

switchmakescontact

withametalbarb

sensingitspresence. If

nocontactismadethe

processwillshutdown.


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ContactMethods

Donothavetobehightech!

Passivedevicesaresometimesthebestmethod. Thesecanbeas simpleas

guidepinsorblocksthatdonotallowpartstobeseatedinthewrongposition

priortoprocessing

Takeadvantageofpartsdesignedwithanunevenshape!

A workpiecewithaholeabumporanunevenendisaperfectcandidatefora

passive jig. Thismethodsignalstotheoperatorrightawaythatthepartisnotin

properposition.


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CountingMethod

Usedwhenafixednumberofoperationsarerequiredwithinaprocess,orwhena

producthasafixednumberofpartsthatareattachedtoit.

A sensorcountsthenumberoftimesapartisusedoraprocessiscompletedand

releasesthepartonlywhentherightcountisreached.

Intheexampletotherightalimitswitchis

usedtodetectandcountwhentherequired

amountofholesaredrilled. Thebuzzersoundsalertingtheoperatorthatthe

appropriateamountofstepshavebeen

takenintheprocess.


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CountingMethod

Anotherapproachistocountthenumberofpartsorcomponentsrequiredto

completeanoperationinadvance. Ifoperatorsfindspartsleftoverusingthis

method,theywillknowthatsomethinghasbeenomittedfromtheprocess.

Ihaveanextra

part. Imusthave

omittedastep!


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Motion-SequenceMethod

Thethirdpoka-yokemethodusessensorstodetermineifamotionorastepina

processhasoccurred.Ifthestephasnotoccurredorhasoccurredoutofsequence,

thethesensorsignalsatimerorotherdevicetostopthemachineandsignalthe

operator.

Thismethodusessensorsandphoto-electricdevicesconnectedtoatimer. Ifmovementdoes

notoccurwhenrequired,theswitchsignalsto

stoptheprocessorwarntheoperator.


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Motion-SequenceMethodInordertohelpoperatorsselecttherightpartsfortherightstepinaprocessthe

sequencingaspectofthemotion-stepmethodisused. Thisisespeciallyhelpfulwhenusingmultiplepartsthataresimilarinsizeandshape.

Inthisexample,eachstepofthemachinecycleiswiredtoanindicatorboardanda

timer. Ifeachcycleofthemachineisnotperformedwithintherequired timeand

sequence,theindicatorlightforthatstepwillbeturnedonandthemachinewill

stop.

IndicatorBoardMachine


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TypesofSensing Devices

Sensingdevicesthataretraditionallyusedinpoka-yoke

systemscanbedividedintothreecategories:

1. Physicalcontactdevices

2. Energysensingdevices

3. Warning Sensors

Eachcategoryofsensorsincludesabroadrangeofdevicesthatcanbeuseddependingontheprocess.


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Physical Contact Sensors

Thesedevicesworkby

physicallytouching

something. Thiscanbea

machinepartoranactual

piecebeing

manufactured.

Inmostcasesthese

devicessendanelectronic

signalwhentheyare

touched. Dependingon

theprocess,thissignalcanshutdowntheoperation

orgiveanoperatora

warningsignal.


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Touch Switch

Usedtophysicallydetectthepresenceorabsenceofanobject

oritem-preventsmissingparts.

Usedtophysicallydetecttheheightofapartordimension.


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Energy Sensors

Thesedevicesworkby

usingenergytodetect

whetherornotandefect

hasoccurred.

Fiberoptic

Photoelectric

Vibration


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Warning Sensors

Warningsensorssignalthe

operatorthatthereisa

problem. Thesesensorsuse

colors,alarms,lightstoget

theworkersattention!

Thesesensorsmaybeused

inconjunctionwithacontact

orenergysensortogetthe

operatorsattention.

Color Code

Lights

Lightsconnectedto

Microswitches &

timers

error proofing techniques

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