AnAn EfficientEfficient CNCCNC ProgrammingProgramming ApproachApproachBasedBased onon GroupGroup TechnologyTechnologyManocherManocher Djassemi,Djassemi, Dept.Dept. ofof IndustrialIndustrial andand EngineeringEngineering Technology,Technology, MurrayMurray StateState University,University, Murray,Murray, Kentucky,Kentucky, USAUSA

AbstractAbstract ManyMany studiesstudies andand reportsreports supportsupport thethe significantsignificant impactimpact ofof

thethe applicationapplication ofof groupgroup technologytechnology onon variousvarious aspectsaspects ofof productproduct designdesign andand manufacturing.manufacturing. TheThe factfact thatthat groupgroup tech­tech­nologynology isis thethe commoncommon solutionsolution toto similarsimilar problemsproblems isis thethe mainmain sourcesource ofof suchsuch impact.impact. InIn thisthis paper,paper, oneone ofof thethe lessless frequent­frequent­lyly utilizedutilized featuresfeatures ofof GNGGNG technologytechnology knownknown asas parametricparametric partpart programmingprogramming isis usedused toto implementimplement thethe commoncommon solutionsolution featurefeature ofof groupgroup technologytechnology inin processingprocessing aa setset ofof similarsimilar parts.parts. UsingUsing threethree partpart families,families, thethe advantagesadvantages ofof blendingblending thethe conceptconcept ofof groupgroup technologytechnology andand parametricparametric programmingprogramming forfor CNCCNC machiningmachining operationsoperations areare illustrated.illustrated. TheThe efficiencyefficiency improvementimprovement duedue toto thethe useuse ofof parametricparametric programmingprogramming inin termsterms ofof numbernumber ofof setupssetups andand sizesize ofof programprogram isis discussed.discussed.

Keywords:Keywords: GroupGroup Technology,Technology, ComputerComputer NumericalNumerical Control,Control, ParametricParametric PartPart ProgrammingProgramming

IntroductionIntroduction GroupGroup TechnologyTechnology (GT)(GT) isis aa broadbroad conceptconcept thatthat

usesuses conunonconunon attributesattributes toto reducereduce redundantredundant workwork inin designdesign andand manufacturingmanufacturing andand resultsresults inin shortershorter productproduct developmentdevelopment andand productionproduction time.time. ThisThis GTGT feature-shorterfeature-shorter productproduct developmentdevelopment andand produc­produc­tiontion time-providestime-provides aa significantsignificant advantageadvantage forfor man­man­ufacturersufacturers byby enablingenabling themthem toto respondrespond fasterfaster toto mar­mar­ketket demand/changesdemand/changes andand runrun productionproduction moremore eco­eco­nomicallynomically inin today'stoday's highlyhighly competitivecompetitive manufactur­manufactur­inging environment.environment.

AA significantsignificant amountamount ofof researchresearch andand casecase studiesstudies inin groupgroup technologytechnology showsshows thatthat GTGT improvesimproves produc­produc­tivitytivity inin oneone oror moremore aspects.aspects. II ,2,2 TheThe applicationapplication ofof GTGT coverscovers areasareas asas diversediverse asas design,design, processprocess planning,planning, tooling,tooling, scheduling,scheduling, partpart programming,programming, andand materialmaterial handling.handling. InIn allall cases,cases, GTGT isis usedused toto findfind aa commoncommon solutionsolution toto aa setset ofof similarsimilar problems,problems, thatthat is,is, design­design­inging similarsimilar productsproducts oror processingprocessing similarsimilar parts.parts. Likewise,Likewise, OTOT isis usedused toto classifyclassify partpart designs,designs, allow­allow­inging thethe efficientefficient groupinggrouping ofof similarsimilar designsdesigns thatthat cancan bebe manufacturedmanufactured onon thethe samesame machinemachine oror machinemachine cell.cell. First,First, thethe approachapproach avoidsavoids duplicationduplication ofof datadata inin

reduc­aa database;database; andand second,second, itit resultsresults inin significantsignificant reduc­

tiontion inin bothboth numbernumber andand varietyvariety ofofCADCAD files,files, processprocess plans,plans, andand NCNC partpart programs.programs. ManyMany companiescompanies inin thethe USUS andand EuropeEurope havehave adoptedadopted OTOT forfor standardizationstandardization ofof designdesign andand productionproduction techniques?techniques?

ThisThis studystudy isis focusedfocused onon thethe implementationimplementation ofof thethe GTGT conceptconcept toto aa specificspecific aspectaspect ofof computer-aidedcomputer-aided manufacturing,manufacturing, thatthat is,is, numericalnumerical controlcontrol (NC)(NC) pro­pro­gramminggramming ofof machiningmachining andand turningturning centers.centers. TheThe commoncommon solutionsolution forfor similarsimilar problemsproblems (CSSP)(CSSP) fea­fea­tureture ofof GTGT andand thethe parametricparametric programmingprogramming capabil­capabil­ityity ofof computercomputer numericalnumerical controlcontrol (CNC)(CNC) machinesmachines willwill bebe usedused toto developdevelop aa singlesingle NCNC programprogram forfor eacheach partpart family.family. ForFor CNCCNC machinemachine users,users, thethe combina­combina­tiontion ofof CSSPCSSP andand parametricparametric programmingprogramming approachesapproaches isis expectedexpected toto createcreate thethe opportunityopportunity toto generategenerate NCNC codescodes andand operateoperate CNCCNC machinesmachines withwith greatergreater efficiency.efficiency. CNCCNC machiningmachining oror turningturning centerscenters lendlend themselvesthemselves toto thethe CSSPCSSP conceptconcept inin twotwo ways:ways: commoncommon toolingtooling andand commoncommon programmingprogramming forfor aa familyfamily ofof parts.parts. WhenWhen aa familyfamily ofof partsparts isis processedprocessed onon thesethese machines,machines, tooltool indexingindexing andand loading/unloadingloading/unloading areare performedperformed lessless frequentlyfrequently becausebecause mostmost partsparts cancan bebe machinedmachined byby aa setset ofof commoncommon tools.tools. Similarly,Similarly, thethe parametricparametric program­program­mingming featurefeature ofof modernmodern CNCCNC machinesmachines allowsallows aa commoncommon programprogram toto bebe usedused forfor machiningmachining aa numbernumber ofof similarsimilar parts.parts.

ConsideringConsidering thethe potentialpotential benefitsbenefits ofof suchsuch anan applicationapplication forfor groupgroup technologytechnology andand CNCCNC machinemachine users,users, aa studystudy toto linklink thethe parametricparametric programmingprogramming techniquetechnique toto OTOT systemsystem isis appropriate.appropriate. UsingUsing threethree examples,examples, thethe efficiencyefficiency improvementimprovement duedue toto thethe jointjoint applicationapplication ofof thethe twotwo technologiestechnologies isis discusseddiscussed inin thethe followingfollowing sections.sections.

ParametricParametric PartPart ProgrammingProgramming Traditionally,Traditionally, separateseparate partpart programsprograms areare writtenwritten forfor

individualindividual partsparts withinwithin aa partpart family;family; thenthen thethe pro­pro­gramsgrams areare loadedloaded toto thethe machinemachine controllercontroller oneone byby one.one.

MostMost CNCCNC machinesmachines havehave aa specialspecial featurefeature knownknown asas parametricparametric programming,programming, alsoalso referredreferred toto asas macro,4macro,4 inin whichwhich aa partpart programprogram cancan bebe writtenwritten usingusing variablesvariables andand parametricparametric expressionsexpressions toto representrepresent thethe machinemachine axisaxis positionposition (x,(x, y,y, z,z, a,a, etc.),etc.), feed,feed, andand speedspeed functions.functions.ss SimilarSimilar toto computercomputer programmingprogramming lan­lan­guagesguages suchsuch asas PascalPascal oror C,C, computer-relatedcomputer-related featuresfeatures suchsuch asas variables,variables, arithmetic,arithmetic, logiclogic statements,statements, andand loopinglooping cancan bebe implementedimplemented inin aa parametricparametric program.program. ThisThis programmingprogramming featurefeature allowsallows thethe useruser toto loadload aa singlesingle partpart programprogram forfor aa familyfamily ofof partsparts toto thethe CNCCNC controller.controller. TheThe partpart programprogram isis thenthen calledcalled upup forfor machiningmachining aa similarsimilar partpart oror similarsimilar featurefeature onon differ­differ­entent parts.parts. TheThe processprocess involvesinvolves aa simplesimple entryentry ofof para­para­metermeter valuesvalues intointo thethe machinemachine controller.controller. ForFor example,example, severalseveral cylindricalcylindrical partsparts maymay havehave twotwo commoncommon para­para­meters,meters, suchsuch asas diameterdiameter andand overalloverall length.length. AA singlesingle parametricparametric partpart programprogram cancan bebe calledcalled upup fi'omfi'om aa mainmain programprogram forfor machiningmachining suchsuch aa groupgroup ofof similarsimilar parts.parts. UponUpon loadingloading thethe mainmain program,program, thethe valuesvalues ofof thethe twotwo parametersparameters areare entered;entered; thenthen thesethese valuesvalues areare trans­trans­ferredferred toto parametricparametric subprograms.subprograms. ThisThis approachapproach couldcould minimizeminimize thethe numbernumber ofof programprogram changeovers,changeovers, reducereduce thethe redundantredundant codescodes inin thethe partpart program,program, andand shortenshorten thethe lengthlength ofof thethe program.program.

MethodologyMethodology InIn thisthis study,study, threethree partpart familiesfamilies areare consideredconsidered toto

investigateinvestigate thethe effectseffects ofof blendingblending CSSPCSSP andand para­para­metricmetric programmingprogramming inin improvingimproving thethe efficiencyefficiency ofof CNCCNC operations.operations. TheThe efficiencyefficiency improvementimprovement isis determineddetermined basedbased onon twotwo factors:factors: (a)(a) numbernumber ofof pro­pro­gramgram changeoverschangeovers andand (b)(b) numbernumber ofof NCNC filesfiles andand sizesize ofof partpart program.program. AsAs thethe numbernumber ofof partpart typestypes withinwithin aa partpart familyfamily increases,increases, thethe numbernumber ofofprogramprogram changeoverschangeovers oror setupssetups isis expectedexpected toto increase.increase. TheThe numbernumber ofof NCNC filesfiles andand thethe sizesize ofof thethe partpart programprogram cancan havehave aa significantsignificant effecteffect onon filefile managementmanagement andand memorymemory spacespace whenwhen thethe numbernumber ofof partpart typestypes withinwithin aa partpart familyfamily isis relativelyrelatively high.high. BasedBased onon thethe afore­afore­mentionedmentioned factors,factors, anan efficiencyefficiency improvementimprovement (EI)(EI) measuremeasure isis defineddefined asas follows:follows:

n-ln-l (I~I(I~I Nln)-PNln)-PEI==-*W+� *(1-W)*(1-W)EI==-*W+ II II

nn (1:,;'(1:,;' NJn)NJn)

wherewhere

n� isis thethe partpart familyfamily sizesizen NNi�i isis thethe numbernumber ofof NCNC instructionsinstructions (lines)(lines) inin thethe

conventionalconventional NCNC programprogram forfor aa partpart typetype ii inin thethe familyfamily

PP isis thethe numbernumber ofof NCNC instructionsinstructions (lines)(lines) inin thethe parametricparametric programprogram forfor thethe samesame partpart familyfamily

WW isis thethe weightweight factorfactor

TheThe methodologymethodology consistsconsists ofof thethe followingfollowing steps:steps:

StepStep 1.1. DevelopDevelop CADCAD filesfiles forfor thethe threethree partpart families.families.

StepStep 2.2. GenerateGenerate NCNC codescodes usingusing CAD/CAMCAD/CAM soft­soft­wareware66 forfor thethe parts'parts' CADCAD files.files.

StepStep 3.3. WriteWrite aa singlesingle parametricparametric programprogram forfor eacheach partpart family.7family.7

StepStep 4.4. CompareCompare thethe twotwo typestypes ofof partpart programsprograms developeddeveloped inin stepssteps 22 andand 33 usingusing thethe EIEI measure.measure.

TheThe weightweight factor,factor, W,W, isis empiricallyempirically determineddetermined usingusing aa BridgeportBridgeport CNCCNC millmill andand aa PC.PC. ItIt waswas observedobserved thatthat thethe ratioratio betweenbetween thethe timestimes toto changechange programs,programs, includingincluding clearingclearing thethe controlcontrol memory,memory, andand locatinglocating aa programprogram toto programprogram downloadingdownloading timetime fromfrom aa PCPC toto CNCCNC isis roughlyroughly 4:14:1 (W(W ==== 80%).80%). ThisThis indicatesindicates thatthat forfor thethe casescases studiedstudied here,here, thethe effecteffect ofof programprogram lengthlength onon EIEI isis notnot asas significantsignificant asas thethe effecteffect ofof machinemachine stoppagestoppage forfor programprogram changingchanging (see(see TableTable 1).1).

AnalysisAnalysis ofof ResultsResults PartPart familyfamily II consistedconsisted ofof fivefive partsparts (n(n ==== 5),5), asas

illustratedillustrated inin FigureFigure 1.1. AA singlesingle parametricparametric partpart pro­pro­gramgram forfor machiningmachining thisthis partpart familyfamily isis shownshown inin thethe Appendix.Appendix.

TheThe numbersnumbers ofof instructionsinstructions inin conventionalconventional NCNC programsprograms forfor individualindividual partpart typestypes werewere 66,66, 37,37, 132,132, 104,104, andand 132.132. TheThe numbernumber ofof executableexecutable NCNC instruc­instruc­tionstions inin thethe correspondingcorresponding parametricparametric programprogram waswas 4545 lines.lines. TheThe overalloverall EIEI duedue toto applicationapplication ofof para-para-

TableTable 11 ProgramProgram ChangeoverChangeover andand DownloadingDownloading TimesTimes (seconds)(seconds)

PartPart FamilyFamily IIII IIIIII

ChangeoverChangeover timetime 4040 3535 27�27 DownloadingDownloading timetime 1111 88 8�8

FigureFigure 11 FigllreFigllre 33 ParIParI FamilyFamily II PartPart FamilyFamily IIIIII

PartPart familyfamily IIII consistedconsisted ofof fourfour partsparts (Figure(Figure 2).2). TheThe numbernumber ofof NCNC instructionsinstructions forfor individualindividual partpart typestypes werewere 27,27, 53,53, 8,8, andand 3434 lineslines forfor thisthis group.group. TheThe numbernumber ofNCofNC instructionsinstructions inin thethe correspondingcorresponding para­para­metricmetric programprogram waswas 2525 lineslines (see(see thethe Appendix).Appendix). TheThe useuse ofof parametricparametric programmingprogramming resultedresulted inin aa 64%64% improvementimprovement inin programmingprogramming efficiency.efficiency. WhenWhen aa largerlarger numbernumber ofof similarsimilar partsparts (n(n == 15)15) werewere includedincluded byby changingchanging thethe valuevalue ofof thethe parameters,parameters, includingincluding externalexternal radius,radius, thickness,thickness, diameterdiameter ofof centercenter pocket,pocket, andand numbernumber ofofholes,holes, thenthen thethe EIEI improvedimproved fromfrom 64%64% toto 78%.78%.

FigureFigure 22 PartPart familyfamily IIIIII consistedconsisted ofof fourfour partsparts (Figure(Figure 3).3).PartPart FamilyFamily IIII

TheThe numbernumber ofof NCNC instructionsinstructions inin thethe conventionalconventional partpart programprogram remainedremained atat 5353 forfor allall partpart types.types. TheThe

metricmetric programmingprogramming waswas 74%.74%. However,However, ifif thethe num­num­ numbernumber ofof NCNC instructionsinstructions inin thethe correspondingcorresponding para­para­berber ofofpartpart typestypes inin thethe partpart familyfamily growsgrows andand thethe newnew metricmetric programprogram waswas 2525 lines.lines. TheThe useuse ofof parametricparametric partpart membersmembers areare differentdifferent fromfrom thethe oldold onesones onlyonly inin programmingprogramming resultedresulted inin aa 64%64% improvementimprovement inin pro­pro­termsterms ofof valuesvalues ofof specifiedspecified parametersparameters inin thethe pro­pro­ gramminggramming efficiencyefficiency forfor thisthis partpart family.family. ByBy changingchanging gram,gram, suchsuch asas diameterdiameter andand overalloverall length,length, thenthen EIEI thethe valuevalue ofof fourfour parameters,parameters, includingincluding length,length, width,width, yieldsyields greatergreater efficiencyefficiency inin programmingprogramming thethe CNCCNC thickness,thickness, andand numbernumber ofof slots,slots, additionaladditional partsparts maymay bebe machine.machine. ForFor example,example, forfor 1515 partpart typestypes (n(n ;=:;=: 15)15) thethe includedincluded inin thisthis group.group. IncreasingIncreasing thethe numbernumber ofof partpart EIEI increasesincreases fromfrom 75%75% toto 85%.85%. typestypes toto 1515 improvedimproved thethe EIEI fi:omfi:om 64%64% toto 85%.85%.

TableTable 22 SummarySummary ofof NumericalNumerical ResultsResults

No.No. ofof Avg.Avg. No.No. ofof No.No. ofof EfficiencyEfficiency EfficiencyEfficiency PartPart InstructionInstruction InstructionInstruction inin ImprovementImprovement ImprovementImprovement

No.No. ofof TypesTypes No.No. ofof LinesLines perper ParametricParametric (EI)(EI) (EI)(EI) PartPart ProgramProgram (n)(n) PartPart ProgramProgram PartPart FamilyFamily ProgramProgram n=5n=5 n=15*n=15*

II 55 55 9494 4545 54%54% 85%85% IIII 44 44 3030 2525 25%25% 78%78% IIIIII 44 44 5353 2424 53%53% 85%85%

*The*The numbernumber ofof partpart typestypes inin eacheach familyfamily increasedincreased byby 1515 byby changingchanging thethe valuevalue ofof parameters.parameters.

TableTable 22 summarizessummarizes thethe comparisoncomparison resultsresults ofof thethe twotwo methodsmethods ofNCofNC programmingprogramming appliedapplied toto thethe threethree partpart familiesfamilies underunder study.study.

ConclusionConclusion TheThe resultsresults ofof thisthis studystudy supportsupport thethe findingsfindings ofof

manymany otherother reportsreports andand studiesstudies regardingregarding thethe effectseffects ofof adoptingadopting groupgroup technologytechnology inin improvingimproving thethe effi­effi­ciencyciency ofof manufacturingmanufacturing operations.operations. TheThe parametricparametric programmingprogramming approachapproach waswas usedused asas aa meansmeans toto implementimplement thethe commoncommon solutionsolution forfor similarsimilar problemsproblems (CSSP)(CSSP) featurefeature ofof groupgroup technologytechnology inin CNCCNC machin­machin­inging operationsoperations wherewhere therethere areare somesome similaritiessimilarities amongamong thethe parts.parts. TheThe numericalnumerical resultsresults showedshowed anan improvementimprovement inin efficiencyefficiency ofof NCNC programmingprogramming afterafter applyingapplying thethe parametricparametric programmingprogramming approachapproach toto threethree partpart families.families. SuchSuch improvementimprovement isis moremore signif­signif­icanticant whenwhen thethe numbernumber ofof partpart typestypes 'within'within aa partpart familyfamily isis relativelyrelatively high.high. ItIt isis recommendedrecommended thatthat GTGT usersusers adoptadopt parametricparametric programmingprogramming forfor largelarge partpart familiesfamilies oror wheneverwhenever therethere isis aa growinggrowing trendtrend inin thethe sizesize ofof thethe partpart familyfamily toto minimizeminimize programprogram changeoverschangeovers andand thethe numbernumber ofof similarsimilar NCNC files.files. AA thresholdthreshold valuevalue forfor partpart familyfamily sizesize cancan bebe deter­deter­minedmined basedbased onon aa cost-benefitcost-benefit analysisanalysis consideringconsidering thethe timetime forfor programprogram changeoverchangeover andand thethe timetime toto writewrite thethe NCNC programprogram inin conventionalconventional andand parametricparametric fash­fash­ions.ions.

InIn today'stoday's competitivecompetitive economy,economy, manufacturingmanufacturing companiescompanies havehave nono alternativealternative otherother thanthan takingtaking advantageadvantage ofof thethe newnew technologiestechnologies inin improvingimproving thethe efficiencyefficiency ofof theirtheir operation.operation. ParametricParametric program­program­mingming asas thethe best-keptbest-kept secretsecret ofof modernmodern CNCCNC machinesmachines55 isis alreadyalready atat thethe machinemachine tooltool users'users' dis­dis­posal.posal. SurveysSurveys onon successfulsuccessful applicationsapplications ofofparaparamet­met­ricric partpart programmingprogramming inin groupgroup technologytechnology facilitiesfacilities wouldwould bebe anan appropriateappropriate extensionextension toto thisthis study.study.

AppendiXAppendiX

ParametricParametric PartPart ProgramsPrograms

00010001 (PART(PART FAMILYFAMILY I)I) G20G20 GOGO TOlOlT0101 G97G97 SlS00SlS00 M3M3 G96G96 S1200S1200 (CHECK(CHECK RIGHTRIGHT SHOULDER)SHOULDER)

(PI0(PI0 EXTERNALEXTERNAL DIAMETERDIAMETER OFOF BAR)BAR) (P11(P11 LENGTHLENGTH OFOF RIGHTRIGHT SHOULDER)SHOULDER) (P13(P13 SHOULDERSHOULDER DIAMETER)DIAMETER) IFIF PP1111=0=0 GOTOGOTO N3N3 GOGO X[PI0]+.1X[PI0]+.1 Z.1Z.1 (MACHINING(MACHINING RIGHTRIGHT

SHOULDER)SHOULDER) G71G71 PIPI Q2Q2 1010 KOKO RORO D.05D.OS N1N1 GOGO XX [P13][P13] G1G1 ZOZO ZZ [-Pll][-Pll] XX [P10][P10] N2N2

oo N3N3 THREAD)�(CHECK(CHECK THETHE THREAD) (P12(P12 PASSES)�## OFOF PASSES) (P13(P13 DIAMETER)�MAJORMAJOR DIAMETER) (P14(P14 THREADS/INCH)�## OFOF THREADS/INCH) (PIS(PIS LENGTHLENGTH OFOF THREAD)THREAD) IFIF P12=0P12=0 GOTOGOTO N4N4 GOGO T0202T0202 (MACHINING(MACHINING THETHE UNCUNC THREAD,THREAD,

H=.6495P)H=.6495P) GOGO Z.5Z.S P6=0P6=0 WHILEWHILE P6P6 LTLT [P12][P12] P6=P6+1P6=P6+1 GOGO X[P13-[P6*[[.6495/P14]/P12]]]X[P13-[P6*[[.6495/P14]/P12]]]

Z[-P15] EOOSEOOSG32G32 Z[-P1S] GOGO X[P13]X[P13]GOGO Z.lZ.lWENDWENDN4N4 (CHECK(CHECK LEFTLEFT SHOULDER)SHOULDER)(P16(P16 DISTANCEDISTANCE FROMFROM RIGHTRIGHT FACEFACE TO)TO)(SHOULDER)(SHOULDER)(P17(P17 OVERALLOVERALL LENGTHLENGTH OFOF PART)PART)(P18 DIAMETERDIAMETER OFOF LEFTLEFT SHOULDER)SHOULDER)(PISN3N3 IFIF P16=P17P16=P17 GOTOGOTO N10N10GOGO T0303T0303 (MACHTI"fING(MACHTI"fING LEFTLEFT SHOULDER)SHOULDER)GOGO X[PlO]X[PlO]Z[-P16]Z[-P16]G71G71 P5 Q6Q6 1010 KOKO RORO D.OSD.OSPS N5N5GOGO X[P18]X[P18]G1G1 Z[-P16]Z[-P16]Z[-P17]Z[-P17]X[P18]X[P18]N6N6N10N10GOGO T0404T0404 (CUTOFF(CUTOFF THETHE PART)PART)GOGO X[P10]+.1X[P10]+.1

Z[-PI7]Z[-PI7] GlGl XOXO GlGl X[PlO]+lX[PlO]+l M5M5 M30M30

00020002 (PART(PART FAMILYFAMILY II)II) HOLES)�(PlO(PlO ## OFOF HOLES)

CIRCLE)�(Pll(Pll RADIUSRADIUS OFOF HOLEHOLE CIRCLE) DIAMETER)�(P12(P12 EXTERNALEXTERNAL DIAMETER)

PART)�(P13(P13 THICHNESSTHICHNESS OFOF PART) INCREMENT)�(PI4(PI4 ZZ INCREMENT)

(PISO(PISO RADIUS)�CENTERCENTER POCKETPOCKET RADIUS) (P(P 155155 WIDTH)�CUTCUT WIDTH)

YO�G92G92 X[PX[P 11]11] YO SS10001000 M03M03 DD 11 CONTOUR)�(EXTERNAL(EXTERNAL CONTOUR) M06M06 TOITOI G43G43 HI�HI GOGO 20�20 GOGO YO�X[-PI2]X[-PI2] YO

FIS�GG11 2[2[-P13]-P13] FIS G02G02 X[P12]X[P12] YOYO R[PI2]R[PI2] F80�F80 X[-PI2]�X[-PI2] GOGO 2.1�2.1

GOGO XOXO YOYO POCKET)�(CENTER(CENTER POCKET) F20�F20 G24G24 Z[-P13]Z[-P13] Q[PI4]Q[PI4] FlO�FlO

M06M06 T02T02 PATTERN)�(BOLT(BOLT HOLEHOLE PATTERN) GOGO YO�X[PIl]X[PIl] YO G8lG8l Z[-P13]Z[-P13] R.lR.l F20�F20 GOGO AAOAAO ABOABO R[Pll]�R[Pll]

AB[360/PlO]�AAOAAO AB[360/PlO] P6=O�P6=O

[[PIO]-I]�WHILEWHILE P6P6 LTLT [[PIO]-I] P6=P6+1�P6=P6+1

AA[[360/[PlO]]*P6]�GOGO AA[[360/[PlO]]*P6] AB[[360/[PlO]]*[P6+1]]AB[[360/[PlO]]*[P6+1]] R[Pll]R[Pll] F20F20

WENDWEND MOSMOS M30M30

00030003 (PART(PART FAMILYFAMILY III)III) (PlO(PlO ## OFOF SLOTS)SLOTS) (PU(PU THICKNESSTHICKNESS OFOF PART)PART) (P12(P12 LENGTHLENGTH OFOF PART)PART) (P13(P13 WIDTHWIDTH OFOF PART)PART) (P14(P14 ## OFOF PASSESPASSES ININ Z)Z)

(PIS(PIS SLOTS)�DEPTHDEPTH OFOF SLOTS) G54�G54TOITOI M6�M6

M3�SlOOOSlOOO M3GOGO XOXO YOYO ZO�ZO P6==0�P6==0WHILEWHILE P6P6 LTLT [P14]�[P14] P6==P6+1�P6==P6+1GlGl Z[-[PlllP14]*P6]Z[-[PlllP14]*P6] F5�F5Y[P13]Y[P13] FSO�FSO P7=0�P7=0WHILEWHILE P7P7 LTLT [[PlO]]�[[PlO]] P7==P7+1�P7==P7+1

*P7]�GG11 X[[PX[[P l2/[[Pl2/[[P110]+0]+1]]1]]*P7] 091�091 Y[-P15]�Y[-P15] Y[PlS]�Y[PlS] 090�090 WEND�WEND X[P12]�X[P12] YO�YO XO�XOGOGO Z.l�Z.l WEND�WEND M30�M30

References:References: 1.1. J.1.J.1. Burbidge,Burbidge, "Change"Change toto GroupGroup Technology:Technology: ProcessProcess OrganizationOrganization isis

Obsolete;'Obsolete;' Int'lJournalInt'lJournal a/Productiona/Production ResearchResearch (v30,(v30, 1992),1992), pp1209-1220.pp1209-1220. 2.2. A.M.A.M. Ktieg1er,Ktieg1er, "GT"GT ImprovesImproves Flow,Flow, CutsCuts Costs,"Costs," AmericanAmerican MachinistMachinist

(Mar.(Mar. 1984).1984). 3.3. C.C. MosierMosier andand 1.1. Taube,Taube, "The"The FacetsFacets ofof GroupGroup TechnologyTechnology andand TheirTheir

Impac(sImpac(s onon Implementation-AImplementation-A State-of-the-ArtState-of-the-Art Survey,"Survey," OMEGA,OMEGA, lnt'llnt'l JOl/rnalJOl/rnal ofMgmt.ofMgmt. ScienceScience (v13,(v13, n5,n5, 1985),1985), pp381-391.pp381-391.

4.4. PJ.PJ. Amic,Amic, ComputerComputer NumericalNumerical ControlControl ProgrammingProgramming (Englewood(Englewood Cliffs:Cliffs: Prentice-Hall,Prentice-Hall, 1997),1997), p226.p226.

5.5. M.M. Lynch,Lynch, ManagingManaging CompllterCompllter NumericalNumerical ControlControl Opera/iolls:Opera/iolls: HowHow toto GetGet thethe MostMost OutOut o/YOUI"o/YOUI" eNCeNC MachineMachine ToolsTools (Dearborn,(Dearborn, MI:MI: SocietySociety ofof Mfg,Mfg, Engineers,Engineers, 1995).1995).

6.6. eNCeNC Software,Software, Inc.,Inc., "MasterCAM"MasterCAM MillMill Applica(ionApplica(ion Manua]"Manua]" (Holland,(Holland, CT:CT: 1993).1993).

7.7. MiltronicsMiltronics Mfg.Mfg. Co.,Co., "Centurion"Centurion VV OperationOperation Manual,Manual, VersionVersion 1.3"1.3" (Chanhassen,(Chanhassen, MN:MN: Dec.Dec. 1990).1990).

Author'sAuthor's BiographyBiography ManochcrManochcr DjassemiDjassemi receivedreceived aa BSlEBSlE fromfrom thethe UniversityUniversity ofof ScienceScience andand

TechnologyTechnology inin Tehran,Tehran, Iran,Iran, andand anan MSMS andand PhDPhD fromfrom thethe UniversityUniversity ofof Wisconsin-Milwaukee.Wisconsin-Milwaukee. HeHe isis anan assistantassistant professorprofessor inin thethe Dept.Dept. ofIndustrialofIndustrial andand EngineeringEngineering TechnologyTechnology atat MurrayMurray StateState University.University. HeHe hashas alsoalso taughttaught inin thethe industrialindustrial studiesstudies departmentdepartment atat thethe UniversityUniversity ofof Wisconsin­Wisconsin­Platteville.Platteville. Dr.Dr. DjassemiDjassemi hashas fivefive yearsyears ofof industrialindustrial experienceexperience andand isis aa cer­cer­tifiedtified manufacturingmanufacturing engineer.engineer. HisHis primaryprimary areasareas ofof teachingteaching andand researchresearch areare conventionalconventional andand CNCCNC machinemachine tools,tools, robotics,robotics, CAD/CAM,CAD/CAM, groupgroup tech­tech­nology,nology, andand cellularcellular manufacturing.manufacturing.