Group Technology and Cellular Manufacturing2

7/23/2019 Group Technology and Cellular Manufacturing2

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Group TechnologyGroup Technologyand Cellularand Cellular

ManufacturingManufacturing

Eng. Ahmed Al AfeefyEng. Ahmed Al Afeefy


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What is Group TechnologyWhat is Group Technology

(GT)(GT)?? GT is a theory of management based on theGT is a theory of management based on the

principle that similar things should be doneprinciple that similar things should be done

similarlysimilarly

GT is the realization that many problems areGT is the realization that many problems aresimilar and that by grouping similarsimilar and that by grouping similar

problems a single solution can be found to aproblems a single solution can be found to a

set of problems thus sa!ing time and e"ortset of problems thus sa!ing time and e"ort

GT is a manufacturing philosophy in #hichGT is a manufacturing philosophy in #hichsimilar parts are identi$ed and groupedsimilar parts are identi$ed and grouped

together to ta%e ad!antage of theirtogether to ta%e ad!antage of their

similarities in design and productionsimilarities in design and production&&


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'mplementing GT'mplementing GT

Where to implement GTWhere to implement GT

*lants using traditional batch production*lants using traditional batch production

and process type layoutand process type layout

'f the parts can be grouped into part'f the parts can be grouped into part

familiesfamilies

+o# to implement GT+o# to implement GT

'dentify part families'dentify part families ,earrange production machines into,earrange production machines into

machine cellsmachine cells

--


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Types of ayoutTypes of ayout

In most of todays factories it is possible todivide all the made components into families

and all the machines into groups, in such a way

that all the parts in each family can be

completely processed in one group only.

The three main types of layout are:

Line (product Layout

!unctional Layout

"roup Layout //


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ineine(product)(product)ayoutayoutIt involves the arrangements of machines in one line, depending on

the se#uence of operations. In product layout, if there is a more thanone line of production, there are as many lines of machines.

Line Layout is used at present in simple process industries, in

continuous assembly, and for mass production of components

re#uired in very large #uantities.

00


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1unctional ayout1unctional ayout

In !unctional Layout, all machines of thesame type are laid out together in the same

section under the same foreman. $ach foreman

and his team of wor%ers speciali&e in oneprocess and wor% independently. This type of

layout is based on process speciali&ation.

22


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Group ayoutGroup ayout

In "roup Layout, each foreman and his teamspeciali&e in the production of one list of parts

and co'operate in the completion of common

tas%. This type of layouts based on componentspeciali&ation.

33


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The 4i"erence bet#een group and functionalThe 4i"erence bet#een group and functional

layoutlayout::

55


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arge manufacturing system canarge manufacturing system can

be decomposed into smallerbe decomposed into smaller

subsystems of part families basedsubsystems of part families basedon similarities inon similarities in

6.6. design attributesdesign attributesandand

&.&. manufacturing featuresmanufacturing features

77

'dentifying *art'dentifying *art

1amilies1amilies


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4esign Attributes84esign Attributes8 part con$gurationpart con$guration (round or(round or

prismatic)prismatic)

dimensional en!elopedimensional en!elope (length to(length todiameter ratio)diameter ratio)

surface integritysurface integrity (surface roughness,(surface roughness,

dimensional tolerances)dimensional tolerances) material typematerial type

ra# material statera# material state (casting, forging,(casting, forging,

bar stock, etc.)bar stock, etc.) 6969


1amilies1amilies


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*art Manufacturing 1eatures8*art Manufacturing 1eatures8 operations and operation se:uencesoperations and operation se:uences

(turning, milling, etc.)(turning, milling, etc.)

batch sizesbatch sizes machine toolsmachine tools

cutting toolscutting tools

#or% holding de!ices#or% holding de!ices

processing timesprocessing times

6666


1amilies1amilies


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Group technologyGroup technologyemphasisemphasis

on part families based onon part families based on

similarities in designsimilarities in designattributes and manufacturingattributes and manufacturing

thereforetherefore GTGTcontributes tocontributes to

the integration of CA4 andthe integration of CA4 and

CAM.CAM.

6&6&


1amilies1amilies


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*art 1amilies*art 1amiliesA part family is a collection having

similar:

6-6-

Three methods for identifying parts

families

Visual inspection

Classication and coding

Production ow analysis


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1orming *art 1amilies ;1orming *art 1amilies ;

6.


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incorrect resultsincorrect results

human errorhuman error

di"erent =udgment by di"erentdi"erent =udgment by di"erent

peoplepeople

ine>pensi!eine>pensi!e

least sophisticatedleast sophisticated

good for small companies ha!inggood for small companies ha!ing

smaller number of partssmaller number of parts6060


6.


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&. Classi$cation and Coding&. Classi$cation and CodingCoding8Coding8

The process of assigning symbols to theThe process of assigning symbols to the

parts. Where the symbols representparts. Where the symbols represent

design attributes of partsdesign attributes of partsmanufacturing features of parts or bothmanufacturing features of parts or both

Classi$cation8Classi$cation8

The process of categorization of a setThe process of categorization of a setof parts into part familiesof parts into part families

6262


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A GT code is a string of charactersA GT code is a string of characters

capturing information about an itemcapturing information about an item

Three main types of coding systemsThree main types of coding systems

structure8structure8

Mono?code or hierarchical structureMono?code or hierarchical structure

*oly?code or chain?type structure*oly?code or chain?type structure Mi>ed?mode structureMi>ed?mode structure


Classi$cation and CodingClassi$cation and Coding

6363


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Mono?codeMono?code

6565


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A monocodeA monocode(hierarchical code)(hierarchical code)pro!ides a large amount ofpro!ides a large amount of

information in a relati!ely smallinformation in a relati!ely small

number of digitsnumber of digits @seful for storage and retrie!al of@seful for storage and retrie!al of

design?related information such asdesign?related information such as

part geometry material si!epart geometry material si!eetc.etc.

it is dicult to capture informationit is dicult to capture information

on manufacturing se:uences inon manufacturing se:uences in 6767

Mono?codeMono?code


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*oly?code*oly?code

The code symbols are independent of eachThe code symbols are independent of each

otherother

Each digit in speci$c location of the codeEach digit in speci$c location of the code

describes a uni:ue property of the #or%describes a uni:ue property of the #or%piecepiece

; it is easy to learn and useful init is easy to learn and useful in

manufacturing situations #here themanufacturing situations #here the

manufacturing process ha!e to bemanufacturing process ha!e to be

describeddescribed

; the length of a poly?code may becomethe length of a poly?code may become

e>cessi!e because of its unlimitede>cessi!e because of its unlimited &9&9


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*olycode*olycode

&6&6


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*olycode*olycode

&&&&


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]]Mi>ed?modeMi>ed?mode[[The OPITZThe OPITZ

classification systemclassification system::

it is ait is a mi"edmi"ed(hybrid) coding system(hybrid) coding system de!eloped byde!eloped by #PT$%#PT$% Technical Technical

@ni!ersity of Aachen 6739@ni!ersity of Aachen 6739

it is #idely used in industryit is #idely used in industry it pro!ides a basic frame#or% forit pro!ides a basic frame#or% for

understanding the classi$cation andunderstanding the classi$cation andcoding processcoding process

it can be applied to machined partsit can be applied to machined partsnon?machined parts (both formed andnon?machined parts (both formed andcast) and purchased partscast) and purchased parts

it considers bothit considers both designdesignandandmanufacturingmanufacturinginformationinformation &-&-


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Mi>ed?modeMi>ed?mode

&orm code:

1ocus on part geometry dimensions and features rele!ant topart design

'upplementary code

'ncludes information rele!ant to manufacturing such as ra#material tolerance and surface roughness

'econdary code

'ntended to identify the production operation type and se:uence.

't can be designed by the user $rm to ser!e its o#n needs &/&/


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Basic tructure of the D*T'Basic tructure of the D*T'

&0&0


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Basic tructure of the D*T'Basic tructure of the D*T'

ystemystem

&2&2

C d (di i )1 C d (di it 6 0)


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1orm Code (digits 6 ; 0)1orm Code (digits 6 ; 0)

&3&3

("ample: Optiz part coding System


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("ample: Optiz part coding System

F Given the rotational part design below determine the formcode in the #pti! parts classication and coding system)

'olution

F Length-to-diameter ratio: *+, - .)/ ,igit . - .

F External shape: both ends stepped with screw thread on one end

,igit 0 - /

F Internal shape:part contains a through hole ,igit 1 - .

F Plane surface machining: none

,igit 2 - 3

F Auxiliary holes, gear teeth, etc: none

,igit / - 3 &5&5


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E>ampleE>ample

*art class8*art class8

,otational part 4 H 7.7/.5 I &.9 based on the pitch,otational part 4 H 7.7/.5 I &.9 based on the pitch

circle diameter of the gear so the $rst digit H 6circle diameter of the gear so the $rst digit H 6 E>ternal shape8E>ternal shape8

The part is stepped on one side #ith a functional groo!eThe part is stepped on one side #ith a functional groo!eso the second digit is -so the second digit is -

'nternal shape8'nternal shape8

The third digit is 6 because of the through holeThe third digit is 6 because of the through hole *lain surface machining8*lain surface machining8 The fourth digit is 9 because there is no plain surfaceThe fourth digit is 9 because there is no plain surface

machiningmachining Au>iliary holes and gear teeth8Au>iliary holes and gear teeth8

The $fth digit is 2 because there are spur gear teethThe $fth digit is 2 because there are spur gear teeth

on the parton the part &7&7

1 i * t 1 ili1 i * t 1 ili


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Classi$cation and Coding8Classi$cation and Coding8

*roduction -. 1lo# Analysis (*1A)*roduction -. 1lo# Analysis (*1A) *1A is a method for identifying part families*1A is a method for identifying part familiesand associated machine groupings basedand associated machine groupings based

on the re:uired manufacturing processeson the re:uired manufacturing processes

need for each partneed for each part

-9-9


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election of Classi$cation andelection of Classi$cation and

Coding ystemsCoding ystems4e$ne your ob=ecti!es reasons and users4e$ne your ob=ecti!es reasons and users Try to get consensus so that the classi$cation and codingTry to get consensus so that the classi$cation and coding

system is useful in design purchasing manufacturing :uality etc.system is useful in design purchasing manufacturing :uality etc.

,obustness and E>pandability,obustness and E>pandability

Can it #or% #ith the current product and accommodate un%no#nCan it #or% #ith the current product and accommodate un%no#n

future products and applications.future products and applications.

Automation and EciencyAutomation and Eciency

's it easy to get information in and out in a timely manner and is's it easy to get information in and out in a timely manner and is

the coding system able to handle present and future products.the coding system able to handle present and future products.

implicity and @ser 'nterfaceimplicity and @ser 'nterface Will people use itWill people use it

CostCost

As an engineering decision #ith far reaching impact #hatJs theAs an engineering decision #ith far reaching impact #hatJs the

true costtrue cost

-6-6


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BEKE1'T D1 G,D@*BEKE1'T D1 G,D@*

TEC+KDDGLTEC+KDDGL't a"ects all areas of a company including8't a"ects all areas of a company including8

engineeringengineering e:uipment speci$catione:uipment speci$cation facilities planningfacilities planning process planningprocess planning production controlproduction control :uality control:uality control tool designtool design purchasingpurchasing ser!iceser!ice

-&-&



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TEC+KDDGLTEC+KDDGL

ome of the #ell?%no#n tangible andome of the #ell?%no#n tangible andintangible bene$ts of implementing GT 8intangible bene$ts of implementing GT 8

6.6.Engineering designEngineering design

F ,eduction in ne# parts design,eduction in ne# parts design

F ,eduction in the number of dra#ings,eduction in the number of dra#ings

through standardizationthrough standardization

F ,eduction of number of similar parts easy,eduction of number of similar parts easy

retrie!al of similar functional parts andretrie!al of similar functional parts and

identi$cation of substitute partsidenti$cation of substitute parts

----



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TEC+KDDGLTEC+KDDGL

&. ayout planning&. ayout planning

,eduction in production oor space,eduction in production oor spacere:uiredre:uired

,educed material?handling e"ort,educed material?handling e"ort

-/-/



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TEC+KDDGLTEC+KDDGL

-. peci$cation of e:uipment tools-. peci$cation of e:uipment tools=igs and $>tures=igs and $>tures

tandardization of e:uipmenttandardization of e:uipment 'mplementation of cellular'mplementation of cellular

manufacturing systemsmanufacturing systems

igni$cant reduction in up?front costsigni$cant reduction in up?front costsincurred in the release of ne# partsincurred in the release of ne# partsfor manufacturefor manufacture

-0-0



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TEC+KDDGLTEC+KDDGL

/. Manufacturing8/. Manufacturing8process planningprocess planning

,eduction in setup time and,eduction in setup time andproduction timeproduction time

Alternati!e routing leading toAlternati!e routing leading toimpro!ed part routingimpro!ed part routing

,eduction in number of machining,eduction in number of machiningoperations and numerical controloperations and numerical control(KC) programming time(KC) programming time

-2-2



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TEC+KDDGLTEC+KDDGL

0.0. Manufacturing8 production controlManufacturing8 production control

,educed #or%?in?process in!entory,educed #or%?in?process in!entory

Easy identi$cation of bottlenec%sEasy identi$cation of bottlenec%s 'mpro!ed material o# and reduced'mpro!ed material o# and reduced

#arehousing costs#arehousing costs

1aster response to schedule changes1aster response to schedule changes

'mpro!ed usage of =igs $>tures pallets'mpro!ed usage of =igs $>tures pallets

tools material handling andtools material handling and

manufacturing e:uipmentmanufacturing e:uipment

-3-3


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TEC+KDDGLTEC+KDDGL

2. Manufacturing8 :uality control2. Manufacturing8 :uality control

,eduction in number of defects leading to,eduction in number of defects leading to

reduced inspection e"ortreduced inspection e"ort ,educed scrap generation,educed scrap generation Better output :ualityBetter output :uality

'ncreased accountability of operators and'ncreased accountability of operators andsuper!isors responsible for :ualitysuper!isors responsible for :ualityproduction ma%ing it easier to implementproduction ma%ing it easier to implementtotal :uality control concepts.total :uality control concepts.

-5-5



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TEC+KDDGLTEC+KDDGL

3.3.

*urchasing*urchasing

Coding of purchased part leading toCoding of purchased part leading tostandardized rules for purchasingstandardized rules for purchasing

Economies in purchasing possible becauseEconomies in purchasing possible becauseof accurate %no#ledge of ra# materialof accurate %no#ledge of ra# materialre:uirementsre:uirements

,educed number of part and ra# materials,educed number of part and ra# materials impli$ed !endor e!aluation proceduresimpli$ed !endor e!aluation procedures

leading to =ust?in?time purchasingleading to =ust?in?time purchasing

-7-7



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TEC+KDDGLTEC+KDDGL

5.5.Customer ser!iceCustomer ser!ice

Accurate and faster cost estimatesAccurate and faster cost estimates Ecient spare parts managementEcient spare parts management

leading to better customer ser!iceleading to better customer ser!ice

o#er lead timeso#er lead times

/9/9

C ll l M f t iC ll l M f t i


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Cellular ManufacturingCellular ManufacturingCellular manufacturingCellular manufacturing

is an application of group technology in manufacturing inis an application of group technology in manufacturing in

#hich all or a portion of a $rmJs manufacturing system has#hich all or a portion of a $rmJs manufacturing system has

been con!erted into cellsbeen con!erted into cells

A manufacturing cellA manufacturing cell

is a cluster of machines or processes located in closeis a cluster of machines or processes located in close

pro>imity and dedicated to the manufacturing of a familypro>imity and dedicated to the manufacturing of a familyof partsof parts

Why cellular manufacturing8Why cellular manufacturing8

,educe setup times8 By using part family tooling and ,educe setup times8 By using part family tooling and

se:uencingse:uencing ,educe o# times8 By reducing setup and mo!e times and,educe o# times8 By reducing setup and mo!e times and

#ait time for mo!es and using smaller batch sizes#ait time for mo!es and using smaller batch sizes

,educe in!entories,educe in!entories

,educe lead time,educe lead time /6/6


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Cell 4esignCell 4esign

4esign of cellular manufacturing system4esign of cellular manufacturing system

is a comple> e>ercise #ith broadis a comple> e>ercise #ith broad

implications for an organization.implications for an organization.

TheThe cell design processcell design processin!ol!esin!ol!es

issues related to bothissues related to both systemsystem

structurestructure(tructural 'ssues)(tructural 'ssues) andandsystem operationsystem operation(*rocedures 'ssues)(*rocedures 'ssues)

/&/&

C ll 4 iC ll 4 i


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StructuralStructuralissues includeissues include88 election of part families andelection of part families and

grouping of parts into familiesgrouping of parts into families

election of machine and processelection of machine and process

populations and grouping of these intopopulations and grouping of these into

cellscells

election of tools $>tures and palletselection of tools $>tures and pallets

election of material?handlingelection of material?handling

e:uipmente:uipment

Choice of e:uipment layoutChoice of e:uipment layout

/-/-


C ll 4 iC ll 4 i


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Procedures Issues include:Procedures Issues include:

4etailed design of =obs4etailed design of =obs Drganization of super!isory and supportDrganization of super!isory and support

personnel around the cellular structurepersonnel around the cellular structure 1ormulation of maintenance and inspection1ormulation of maintenance and inspection

policiespolicies 4esign of procedures4esign of procedures for productionfor productionplanningplanning scheduling, controlscheduling, control and and acquisitionacquisitionof related software and hardwareof related software and hardware

Modi$cation of cost control and re#ardModi$cation of cost control and re#ardsystemssystems

Dutline of procedures for interfacing #ith theDutline of procedures for interfacing #ith theremaining manufacturing system (in terms ofremaining manufacturing system (in terms of#or% o# and information #hether#or% o# and information #hether

computer controlled or not)computer controlled or not) ////



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E!aluation of Cell 4esignE!aluation of Cell 4esign

4ecisions4ecisions

The e!aluation of design decisions canThe e!aluation of design decisions can

be categorized as related to eitherbe categorized as related to either the system structurethe system structure

oror

the system operationthe system operation..

/0/0


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Typical considerations related toTypical considerations related to thethesystem structuresystem structureinclude8include8

E:uipment and tooling in!estment (lo#)E:uipment and tooling in!estment (lo#)

E:uipment relocation cost (lo#)E:uipment relocation cost (lo#) Material?handling costs (lo#)Material?handling costs (lo#)

1loor space re:uirements (lo#)1loor space re:uirements (lo#)

E>tent to #hich parts are completed inE>tent to #hich parts are completed ina cell (high)a cell (high)

1le>ibility (high)1le>ibility (high)

/2/2


4ecisions4ecisions


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E!aluations of cell system design areE!aluations of cell system design areincomplete unless they relate to theincomplete unless they relate to the

operation of the systemoperation of the system..

A fe# typical performance !ariablesA fe# typical performance !ariablesrelated torelated to system operationsystem operationare8are8 E:uipment utilization (high)E:uipment utilization (high) Wor%?in?process in!entory (lo#)Wor%?in?process in!entory (lo#)

Nueue lengths at each #or%stationNueue lengths at each #or%station(short)(short)

Oob throughput time (short)Oob throughput time (short)

Oob lateness (lo#)Oob lateness (lo#) /3/3



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Cell 1ormation ApproachesCell 1ormation Approaches

.) 4achine 5 Component Group.) 4achine 5 Component Group

AnalysisAnalysis::

Machine - Component Group AnalsisMachine - Component Group Analsisis based onis based onproduction !o"production !o"

analysisanalysis

/5/5

M hi C tM hi C t


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!roduction "ow analsis!roduction "ow analsisin!ol!es fourin!ol!es four

stages8stages8

tage 68tage 68 #achine classi$cation#achine classi$cation..

Machines are classi$ed on the basisMachines are classi$ed on the basis

of operations that can be performedof operations that can be performed

on them. A machine type number ison them. A machine type number isassigned to machines capable ofassigned to machines capable of

performing similar operations.performing similar operations.

/7/7

Machine ? ComponentMachine ? Component

Group AnalysisGroup Analysis

M hi C tM hi C t


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tage &8tage &8 %hec&ing parts list and%hec&ing parts list and

production route informationproduction route information))

1or each part information on the1or each part information on the

operations to be underta%en and theoperations to be underta%en and the

machines re:uired to perform each ofmachines re:uired to perform each of

these operations is chec%ed thoroughly.these operations is chec%ed thoroughly.


stagesstages::

0909



hi


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tage -8tage -8 'actory !o" analysis'actory !o" analysis))

This in!ol!es a micro?le!elThis in!ol!es a micro?le!el

e>amination of o# of componentse>amination of o# of components

through machines. This in turnthrough machines. This in turn

allo#s the problem to be decomposedallo#s the problem to be decomposed

into a number of machine?componentinto a number of machine?component

groups.groups.


stagesstages::

0606



Machine ComponentMachine Component


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tage /8tage /8 #achine-component group#achine-component group

analysisanalysis))

An intuiti!e manual method isAn intuiti!e manual method issuggested to manipulate the matri> tosuggested to manipulate the matri> to

form cells. +o#e!er as the problemform cells. +o#e!er as the problem

size becomes large the manualsize becomes large the manual

approach does not #or%. Thereforeapproach does not #or%. Thereforethere is a need to de!elop analyticalthere is a need to de!elop analytical

approaches to handle large problemsapproaches to handle large problems

systematically.systematically.


stagesstages::

0&0&





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E>ample8 Consider a problem of / machinesE>ample8 Consider a problem of / machines

and 2 parts. Try to group them.and 2 parts. Try to group them.

achines 1 2 3 4 5 6

M1 ) ) )

M2 ) ) )

M3 ) ) )

M4 ) ) )

Components

0-0-





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achines 2 4 6 1 3 5

M1 ) ) )

M2 ) ) )

M3 ) ) )

M4 ) ) )

Components

0/0/



olutioolutio

nn


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,an% Drder Clustering,an% Drder Clustering

AlgorithmAlgorithm

(an& Order %lustering Algorithm(an& Order %lustering Algorithm

is a simple algorithm used to formis a simple algorithm used to form

machine-part groupsmachine-part groups

0000


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tep 68 Assign binary #eight andtep 68 Assign binary #eight and

calculate a decimal #eight for eachcalculate a decimal #eight for each

ro# and column using the follo#ingro# and column using the follo#ingformulas8formulas8

*ecimal we

*ecimal we bp+ n p

ight for row i , b

ight for column + ,

ipm'p

p,)

m

p,)

n

2

2

0202


AlgorithmAlgorithm


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tep &8 ,an% the ro#s in order oftep &8 ,an% the ro#s in order ofdecreasing decimal #eight !alues.decreasing decimal #eight !alues.

tep -8 ,epeat steps 6 and & for eachtep -8 ,epeat steps 6 and & for eachcolumn.column.

tep /8 Continue preceding steps untiltep /8 Continue preceding steps untilthere is no change in the position ofthere is no change in the position of

each element in the ro# and theeach element in the ro# and the

column.column. 0303


AlgorithmAlgorithm

an r er us er ngan r er us er ng


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E>ample8E>ample8

Consider a problem of 0 machines and 69 parts. TryConsider a problem of 0 machines and 69 parts. Try

to group them by usingto group them by using#ank $rder Clustering#ank $rder ClusteringAlgorithm.Algorithm.

achines 1 2 3 4 5 6 7 8 9 10

M1 ) ) ) ) ) ) ) ) )

M2 ) ) ) ) )

M3 ) ) ) )

M4 ) ) ) ) ) )

M5 ) ) ) ) ) ) ) )

Components

Table .

0505

an r er us er ngan r er us er ngAlgorithmAlgorithm


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achines 1 2 3 4 5 6 7 8 9 10 Decimalequivalent

M1 ) ) ) ) ) ) ) ) ) )--

M2 ) ) ) ) ) /0)

M3 ) ) ) ) 012

M4 ) ) ) ) ) ) /00

M5 ) ) ) ) ) ) ) ) )-3-

29 28 27 26 25 24 23 22 21 206inary weight

Components

Table 0

0707


AlgorithmAlgorithm

% d l i


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4inaryweight

achines 1 2 3 4 5 6 7 8 9 10

24 M5 ) ) ) ) ) ) ) )

23 M1 ) ) ) ) ) ) ) ) )

22 M3 ) ) ) )

21 M4 ) ) ) ) ) )

20 M2 ) ) ) ) )

Decimal

equivalent

32 3 3 3 32 3- 32 31 )) ))

29 28 27 26 25 24 23 22 21 20

6inary weight

Components

Table 1

2929


AlgorithmAlgorithm

% D d Cl i


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4inaryweight

achines 1 5 7 2 3 4 8 6 9 10 Decimalequivalent

24 M5 ) ) ) ) ) ) ) ) )-3-

23 M1 ) ) ) ) ) ) ) ) ) )-)5

22 M3 ) ) ) ) 5--

21 M4 ) ) ) ) ) ) )36

20 M2 ) ) ) ) ) ))0

Decimalequivalent

32 32 32 3 3 3 31 3- )) ))

29 28 27 26 25 24 23 22 21 20

6inary weight

Components

Table 2

2626


AlgorithmAlgorithm

, % D d Cl t i,an% Drder Clustering


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,D clustering oscillations indicating need ofmachine replication (happens oftenP)

*resence of Dutliers andor


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The ,DC pro!ides a simple analyticalThe ,DC pro!ides a simple analytical

techni:ue that can be easilytechni:ue that can be easily

computerizedcomputerizedThe ,DC has fast con!ergence andThe ,DC has fast con!ergence and

relati!ely lo# computation timerelati!ely lo# computation time

depending on the matri> sizedepending on the matri> size

The fact that ,DC uses binary !aluesThe fact that ,DC uses binary !alues

#ill impose restrictions on the size of#ill impose restrictions on the size of

the matri> that can be sol!edthe matri> that can be sol!ed2-2-


AlgorithmAlgorithm



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Most computers ha!e a ma>imum ofMost computers ha!e a ma>imum of&&/5/5?6 for integer representation #hich?6 for integer representation #hich

means that the ma>imum number ofmeans that the ma>imum number of

ro#s and columns is limited to /3 andro#s and columns is limited to /3 andcolumns is limited to /3columns is limited to /3

The algorithm results depend on theThe algorithm results depend on the

initial matri> arrangementinitial matri> arrangement

The algorithm collects positi!e entriesThe algorithm collects positi!e entries

(6s) in the top left?hand corner lea!ing(6s) in the top left?hand corner lea!ing

the rest of the matri> disorganizedthe rest of the matri> disorganized

2/2/


AlgorithmAlgorithm


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Cluster 'denti$cationCluster 'denti$cation


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These mas%ed columns and ro#s areThese mas%ed columns and ro#s are

placed in a bloc% and remo!ed from theplaced in a bloc% and remo!ed from the

matri> remo!ed from the matri>.matri> remo!ed from the matri>.

Then the process of mas%ing starts againThen the process of mas%ing starts againand another bloc% is identi$ed.and another bloc% is identi$ed.

This #ill continue until all the entries inThis #ill continue until all the entries in

the matri> are assigned in bloc%s and allthe matri> are assigned in bloc%s and all

separable bloc%s are identi$edseparable bloc%s are identi$ed

2222


Algorithm (C'A)Algorithm (C'A)



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Algorithm (C'A)Algorithm (C'A)("ample:

tep 6.elect any ro# i of the incidence matri> anddra# a horizontal line hi through it.

,o# - of the matri> is selected randomly and ahorizontal line h- is dra#n.



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Algorithm (C'A)Algorithm (C'A)tep &.1or each entry of 6 crossed by the horizontalline h-

dra# a !ertical line !=.

Three !ertical lines !& !2 and !3 are dra#n



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Algorithm (C'A)Algorithm (C'A)tep -.1or each entry of 6 crossed once by a !erticalline !=

dra# a horizontal line. A horizontal line h2 is dra#n

through all the crossed?once entries of the matri>8

Cluster 'denti$cation AlgorithmCluster 'denti$cation Algorithm


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gg(C'A)(C'A)

tep /.The preceding steps are repeated until no morecrossed once entries are left.

All the crossed?t#ice entries are grouped in a bloc% andremo!ed from the matri>.

*arts & 2 3 and machines - 2 are grouped in one bloc%.



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(C'A)(C'A)

The grouped parts and machines are remo!ed from thematri>



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3&3&


Algorithm (C'A)Algorithm (C'A)tep 08The abo!e procedure is repeated for the

remaining matri> entries until all entries are grouped



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3-3-


Algorithm (C'A)Algorithm (C'A)

The resulting matri> is as follo#s8

Arranging 4achines in a GT Cell


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F After part5machine grouping have been identied bycell formation approaches the ne"t problem is toorgani!e the machines into the most logical

arrangement)

F 7ollier 4ethod) This method uses the sums of ow&rom and To each machine in the cell) The methodcan be outlined as follows

) *e+elop the 'rom-o chart from part routing data Thedata contained in the chart indicates numbers of partmoves between the machines in the cell)

*etermine the 'romand osums for each machineThis is accomplished by summing all of the &romtrips

and Totrips for each machine) The &romsum for a machine is determined by adding the entries

in the corresponding row)

The Tosum is found by adding the entries in the correspondingcolumn)

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. Assign machines to the cell /ased on minimum 'romArranging 4achines in a GT Cell


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. Assign machines to the cell /ased on minimum 'rom or o sums The machine having the smallest sum isselected)

$f the minimum value is a Tosum then the machine is placed atthe beginning of the se8uence)

$f the minimum value is a &romsum then the machine is placedat the end of the se8uence)

Tie brea9er

$f a tie occurs between minimum

To

sums or minimum

&rom

sums then the machine with the minimum &rom+To ratio isselected)

$f both Toand &romsums are e8ual for a selected machine it ispassed over and the machine with the ne"t lowest sum isselected)

$f a minimum To sum is e8ual to a minimum &rom sum thenboth machines are selected and placed at the beginning and endof the se8uence respectively

0 (eformat the 'rom-o chart After each machine has been

selected restructure the &rom5To chart by eliminating the rowand column corres ondin to the selected machine and3030

("ample of Arranging 4achines in a GT Cell


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F 'uppose that four machines . 0 1 and 2 have beenidentied as belonging in a GT machine cell) An analysisof /3 parts processed on these machines has been

summari!ed in the &rom5To chart presented below)Additional information is that /3 parts enter themachine grouping at machine 1 03 parts leave afterprocessing at machine . and 13 parts leave aftermachine 2) ,etermine a logical machine arrangementusing 7ollier method)

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("ample of Arranging 4achines in a GT CellF &irst iteration


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F &irst iteration

3333

("ample of Arranging 4achines in a GT CellF 'econd iteration with machine 1 removed


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F 'econd iteration with machine 1 removed)

3535


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("ample of Arranging 4achines in a GT Cell


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F The ow diagram for machine cell in the ("ample isshown below) &low of parts into and out of the cellshas also been included

5959

lli h d+ lli M th d


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+ollier Method+ollier Method

5656

lli h d+ lli M th d


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+ollier Method+ollier Method

5&5&

+ lli M h d & E l+ lli M th d & E l


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+ollier Method & E>ample+ollier Method & E>ample

esulting machine se8uence 1 ; 0 ; . ; 2

Documents

Group Technology and Cellular Manufacturing2