facility layout
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Production Plant Layout (1)Production Plant Layout (1)
• Facility Layout Problem: design problemFacility Layout Problem: design problem– locations of activitieslocations of activities– dimensionsdimensions– configurationsconfigurations
• No overall algorithm existsNo overall algorithm exists
Design problem
Greenfield Location of one new machine
Production Plant Layout (2)Production Plant Layout (2)
• Reasons:Reasons:– new productsnew products– changes in demandchanges in demand– changes in product designchanges in product design– new machines new machines – bottlenecksbottlenecks– too large bufferstoo large buffers– too long transfer timestoo long transfer times
Production Plant Layout (2)Production Plant Layout (2)
DesignDesign
Layout
Product
Logistics Process
Production Plant Layout (3)Production Plant Layout (3)
• Goals (examples):Goals (examples):– minimal material handling costsminimal material handling costs– minimal investmentsminimal investments– minimal throughput timeminimal throughput time– flexibilityflexibility– efficient use of spaceefficient use of space
Production Plant Layout (4)Production Plant Layout (4)
• Restrictions:Restrictions:– legislation on employees working legislation on employees working
conditionsconditions– present building (columns/waterworks)present building (columns/waterworks)
• Methods:Methods:– Immer: The right equipment at the right Immer: The right equipment at the right
place to permit effective processingplace to permit effective processing– Apple: Short distances and short timesApple: Short distances and short times
Goals Production Plant LayoutGoals Production Plant Layout
• Plan for the preferred situation in the Plan for the preferred situation in the futurefuture
• Layout must support objectives of the facilityLayout must support objectives of the facility
• No accurate data No accurate data layout must be flexible layout must be flexible
Selection
Search
Analysis
Systematic Layout PlanningSystematic Layout Planning Muther (1961) Muther (1961)
0 Data gathering
10 Evaluation
4 Space requirements
5 Space available
6 Space relationship diagram
1 Flow 2 Activities
3 Relationship diagram
7 Reasons to modify
8 Restrictions
9 Layout alternatives
0 - Data gathering (1)0 - Data gathering (1)• Source: product designSource: product design
– BOMBOM– drawingsdrawings– ““gozinto” (assembly) chart, see fig 2.10gozinto” (assembly) chart, see fig 2.10– redesign, standardization redesign, standardization simplifications simplifications
machines
product design
sequence of assembly operations
layout (assembly) line
0 - Data gathering (2)0 - Data gathering (2)
• Source: Process designSource: Process design– make/buymake/buy– equipment usedequipment used– process timesprocess times
operations process chart operations process chart (fig 2.12)(fig 2.12)
assembly chartassembly chart
operations operations
precedence diagramprecedence diagram(fig 2.13)(fig 2.13)
0 - Data gathering (3)0 - Data gathering (3)
• Source: Production schedule designSource: Production schedule design– logistics: where to produce, how much logistics: where to produce, how much
product mixproduct mix– marketing: demand forecast marketing: demand forecast
production rateproduction rate– types and number of machinestypes and number of machines– continuous/intermittentcontinuous/intermittent– layout layout schedule schedule
1/2 - Flow and Activity Analysis1/2 - Flow and Activity Analysis
• Flow analysis:Flow analysis:– Types of flow patternsTypes of flow patterns– Types of layoutTypes of layout
flow analysis approachesflow analysis approaches
• Activity relationship analysisActivity relationship analysis
1/2 - Flow analysis and activity 1/2 - Flow analysis and activity analysisanalysis
Flow analysisFlow analysis
• quantitative measure of movements quantitative measure of movements between departments:between departments:material handling costsmaterial handling costs
Activity analysisActivity analysis
• qualitative factorsqualitative factors
Flow analysisFlow analysis
• Flow of materials, equipment and Flow of materials, equipment and personnelpersonnel
Raw material Finished product
layout facilitates this flowlayout facilitates this flow
Types of flow patternsTypes of flow patterns
P = receivingP = receivingS = shippingS = shipping
R S
R S
R
S
long line
• Horizontal transportHorizontal transport
LayoutLayout
volumes of productionvolumes of production
variety of productsvariety of products
• volumes: what is the right measure of volumes: what is the right measure of volume from a layout perspective?volume from a layout perspective?
• variety variety high/low commonality high/low commonality
layout typelayout type
Types of layoutTypes of layout
• Fixed product layoutFixed product layout
• Product layoutProduct layout
• Group layoutGroup layout
• Process layoutProcess layout
Fixed product layoutFixed product layout
• Processes Processes product (e.g. shipbuilding) product (e.g. shipbuilding)
Product layout (flow shop)Product layout (flow shop)
• Production line according to the Production line according to the processing sequence of the productprocessing sequence of the product
• High volume productionHigh volume production
• Short distancesShort distances
Process layout (Job shop)Process layout (Job shop)
• All machines performing a particular All machines performing a particular process are grouped together in a process are grouped together in a processing departmentprocessing department
• Low production volumesLow production volumes
• Rapid changes in the product mixRapid changes in the product mix
• High interdepartmental flowHigh interdepartmental flow
Group layoutGroup layout
• Compromise between product layout Compromise between product layout and process layoutand process layout
• Product layouts for product families Product layouts for product families cells (cellular layout)cells (cellular layout)
• Group technologyGroup technology
Production volume and product variety Production volume and product variety determines type of layoutdetermines type of layout
group layout process layout
product variety
production volume
product layout
Layout determinesLayout determines
• material handlingmaterial handling
• utilization of space, equipment and utilization of space, equipment and personnel (table 2.2)personnel (table 2.2)
Flow analysis techniquesFlow analysis techniques
• Flow process charts Flow process charts product layout product layout
• From-to-chart From-to-chart process layouts process layouts
Activity relationship analysis Activity relationship analysis
• Relationship chart (figure 2.24)Relationship chart (figure 2.24)
• Qualitative factors (Qualitative factors (subjective!subjective!))
• Closeness rating (A, E, I, O, U or X)Closeness rating (A, E, I, O, U or X)
3 - Relationship diagrams3 - Relationship diagrams
• Construction of relationships diagrams: Construction of relationships diagrams: diagrammingdiagramming
• Methods, amongst others: CORELAPMethods, amongst others: CORELAP
Relationship diagram (1)Relationship diagram (1)
• Spatial picture of the relationships Spatial picture of the relationships between departmentsbetween departments
• Constructing a relation diagram often Constructing a relation diagram often requires compromises. requires compromises. What is closeness? 10 or 50 meters?What is closeness? 10 or 50 meters?
• See figure 2.25See figure 2.25
Relationship diagram (2)Relationship diagram (2)
PremisePremise:: geographic geographic proximityproximity reflects the reflects therelationshipsrelationships
Sometimes other solutions:Sometimes other solutions:– e.g. X-rating because of noise e.g. X-rating because of noise acoustical acoustical
panels instead of distance separationpanels instead of distance separation– e.g. A rating because of communication e.g. A rating because of communication
requirement requirement computer network instead of proximitycomputer network instead of proximity
Graph theory based approachGraph theory based approach
• close close adjacent adjacent
• department-nodedepartment-node
• adjacent-edgeadjacent-edge
• requirement: graph is planar requirement: graph is planar (no intersections)(no intersections)
• region-faceregion-face
• adjacent faces: share a common edgeadjacent faces: share a common edge
graphgraph
Primal graph Primal graph dual graph dual graph
• Place a node in each face Place a node in each face
• Two faces which share an edge – join Two faces which share an edge – join the dual nodes by an edgethe dual nodes by an edge
• Faces dual graph correspond to the Faces dual graph correspond to the departments in primal graph departments in primal graph block layout (plan) e.g. figure 2.39block layout (plan) e.g. figure 2.39
Graph theoryGraph theory
• Primal graph planar Primal graph planar dual graph dual graph planarplanar
• Limitations to the use of graph theory: Limitations to the use of graph theory: it may be an aid to the layout designerit may be an aid to the layout designer
CORELAPCORELAP
• Construction “algorithm” Construction “algorithm”
• Adjacency!Adjacency!
• Total closeness rating = sum of Total closeness rating = sum of absolute values for the relationships absolute values for the relationships with a particular department.with a particular department.
jiji rTCR
CORELAP - stepsCORELAP - steps
1.1. sequence of placements of sequence of placements of departmentsdepartments
2.2. location of departmentslocation of departments
CORELAP – step 1CORELAP – step 1
• First department: First department:
• Second department: Second department: – X-relation X-relation “last placed department” “last placed department”– A-relation with first. If noneA-relation with first. If none E-relation E-relation
with first, etceterawith first, etcetera
iiTCRmax
CORELAP – step 2CORELAP – step 2
• Weighted placement valueWeighted placement value
1st
8
1
2 3
7 6
5
4
2nd
4 - Space requirements4 - Space requirements
• Building geometry or building site Building geometry or building site space availablespace available
• Desired production rate, distinguish:Desired production rate, distinguish:– Engineer to order (ETO)Engineer to order (ETO)– Production to order (PTO)Production to order (PTO)– Production to stock (PTS)Production to stock (PTS)
marketing forecast marketing forecast productions quantities productions quantities
4 - Space requirements4 - Space requirements
Equipment requirements:Equipment requirements:
• Production rate Production rate number of machines number of machines requiredrequired
• Employee requirementsEmployee requirements
rate
machine operators
machines employees
assembly
Space determinationSpace determination
Methods:Methods:1. Production center1. Production center
2. Converting2. Converting
4. Standards4. Standards
5. Projection5. Projection
4 - Space determination (1)4 - Space determination (1)
1. Production center1. Production center• for manufacturing areasfor manufacturing areas• machinemachinespace requirementsspace requirements
2. Converting2. Converting• e.g. for storage arease.g. for storage areas• present space requirement present space requirement space space
requirementsrequirements• non-linear function of production quantitiynon-linear function of production quantitiy
# machines per operator
# assembly operatorsSpace requirements
4 - Space determination (2)4 - Space determination (2)
4.4. Space standardsSpace standards– standardsstandards
5.5. Ratio trend and projectionRatio trend and projection– e.g. direct labour hour, unit producede.g. direct labour hour, unit produced
– Not accurate!Not accurate!– Include space for: Include space for:
packaging, storage, maintenance, offices, aisles, packaging, storage, maintenance, offices, aisles, inspection, receiving and shipping, canteen, tool inspection, receiving and shipping, canteen, tool rooms, lavatories, offices, parkingrooms, lavatories, offices, parking
factor
space
Deterministic approach (1)Deterministic approach (1)
• n’ = # machines per operator (non-integer)n’ = # machines per operator (non-integer)• a = concurrent activity timea = concurrent activity time• t = machine activity timet = machine activity time• b= operatorb= operator
ba
tan
'
Deterministic approach (2)Deterministic approach (2)
bam
taTc
• TTcc = cycle time = cycle time• a = concurrent activity timea = concurrent activity time• t = machine activity timet = machine activity time• b = operator activity timeb = operator activity time• m = # machines per operatorm = # machines per operator
Deterministic approach (3)Deterministic approach (3)
m
TmCCmTC c
21)(
• TC(m) = cost per unit produced as a function of mTC(m) = cost per unit produced as a function of m• CC11 = cost per operator-hour = cost per operator-hour• CC22 = cost per machine-hour = cost per machine-hour
• Compare TC(n) and TC(n+1) for n < n’ < n+1Compare TC(n) and TC(n+1) for n < n’ < n+1
Designing the layout (1)Designing the layout (1)
• Search phaseSearch phase• Alternative layoutsAlternative layouts• Design process includesDesign process includes
– Space relationship diagramSpace relationship diagram– Block planBlock plan– Detailed layoutDetailed layout– Flexible layoutsFlexible layouts– Material handling systemMaterial handling system– PresentationPresentation
Designing the layout (2)Designing the layout (2)
• Relationship diagram + space Relationship diagram + space
space relationship diagram space relationship diagram
(see fig 2.56)(see fig 2.56)
• Different shapesDifferent shapes
9 – Layout alternatives9 – Layout alternatives
• Alternative layouts by shifting the Alternative layouts by shifting the departments to other locations departments to other locations
block plan, also shows e.g. columns block plan, also shows e.g. columns and positions of machines and positions of machines (see fig 2.57)(see fig 2.57)
selection
detailed design
detailed design
selectionor
Flexible layoutsFlexible layouts
• Future Future
• Anticipate changesAnticipate changes
• 2 types of expansion: 2 types of expansion: 1.1. sizessizes
2.2. number of activitiesnumber of activities
Material handling systemMaterial handling system
• Design in parallel with layoutDesign in parallel with layout
• PresentationPresentation– CAD templates 2 or 3 dimensionalCAD templates 2 or 3 dimensional– simulationssimulations– ““selling” the layout (+ evaluation)selling” the layout (+ evaluation)
10 Evalution (1)10 Evalution (1)
Selection and implementationSelection and implementation• best layoutbest layout
– cost of installation + operating costcost of installation + operating cost– compare compare futurefuture costs for both the new and the old costs for both the new and the old
layoutlayout
• other considerationsother considerations– selling the layoutselling the layout– assess and reduce resistanceassess and reduce resistance
• anticipate amount of resistance for each alternativeanticipate amount of resistance for each alternative
10 Evalution (2)10 Evalution (2)
• Causes of resistance:Causes of resistance:– inertiainertia– uncertaintyuncertainty– loss of job contentloss of job content– ……
• Minimize resistance byMinimize resistance by– participationparticipation– stagesstages
ImplementationImplementation
• InstallationInstallation– planningplanning
• Periodic checks after installationPeriodic checks after installation
Systematic Layout PlanningSystematic Layout Planning0 Data gathering
10 Evaluation
Analysis
Search
Selection
4 Space requirements
5 Space available
6 Space relationship diagram
1 Flow 2 Activities
3 Relationship diagram
7 Reasons to modify
8 Restrictions
9 Layout alternatives
Systematic Layout PlanningSystematic Layout Planning0 Data gathering
10 Evaluation
Analysis
Search
Selection
4 Space requirements
5 Space available
6a Space relationship diagram
1 Flow 2 Activities
3 Relationship diagram
7 Reasons to modify
8 Restrictions
9 Layout alternatives
6b Analytical analyses
Automatic Guided Vehicles (AGV’s)Automatic Guided Vehicles (AGV’s)
• Unmanned vehicle for in-plant transportation on Unmanned vehicle for in-plant transportation on manufacturing and assembly areasmanufacturing and assembly areas
• Two types of guidanceTwo types of guidance– free rangingfree ranging
• dead reckoning + lasers or transpondersdead reckoning + lasers or transponders
– path restrictedpath restricted• induction wires in the floorinduction wires in the floor
• AGV AGV fork lift truck with RF-communicationfork lift truck with RF-communication
Design and operational control of an Design and operational control of an AGV systemAGV system
• AGV systemAGV system– track layouttrack layout– number of AGVsnumber of AGVs– operational controloperational control
• Traffic control: zonesTraffic control: zones
max. throughput max. throughput capacitycapacity
Track layoutTrack layout• infrastructureinfrastructure
• location of pick-up and drop-off stationslocation of pick-up and drop-off stations
• buffer sizesbuffer sizes– congestion/blockingcongestion/blocking
• tandem configurationtandem configuration
Determination of number of AGVsDetermination of number of AGVs
h
timetravelemptytotaltvAGVs i j
ijij
)min(#
5 x
6 x
4 x LP-problem(i.e. a classical TP)
Operational transportation controlOperational transportation control
Job controlJob control(routing and scheduling of transportation tasks)(routing and scheduling of transportation tasks)
Traffic controlTraffic controlTraffic rulesTraffic rules• Goal: minimize empty travel + waiting timeGoal: minimize empty travel + waiting time
• Single load:Single load: Performance indicators:Performance indicators:- Throughput- Throughput- Throughput times- Throughput times
Operational controlOperational control
• production control production control transportation controltransportation control– flow shopflow shop– job shopjob shop
• centralized controlcentralized control– all tasks are concurrently consideredall tasks are concurrently considered
• or decentralized controlor decentralized control– FEFS: AGV looks for work (suited for tandem configuration)FEFS: AGV looks for work (suited for tandem configuration)
• think-aheadthink-ahead– combine tasks to routescombine tasks to routes
• or no think-aheador no think-ahead
Relations between the issuesRelations between the issues
Combination 1 Combination 1 Separated/no think-aheadSeparated/no think-ahead
• centralized controlcentralized control• on-line priority rules:on-line priority rules:
1.1. transportation task assignmenttransportation task assignmenttasks wait, ortasks wait, or
2.2. idle vehicle assignmentidle vehicle assignmentidle vehicles waitidle vehicles wait
Ad 1: push/pull (JIT), e.g. FCFS, MOQRSAd 1: push/pull (JIT), e.g. FCFS, MOQRS Push Push sometimes “shop locking” sometimes “shop locking”
Ad 2: NV, LIVAd 2: NV, LIV
Combination 3 Combination 3 Separated/think-ahead (1)Separated/think-ahead (1)
• Centralized controlCentralized controla. without time windowsa. without time windows
– Only routingOnly routing– Minimize empty travel time by simulated annealing:Minimize empty travel time by simulated annealing:
– 2 options:2 options:• determine optimal route each time a new task determine optimal route each time a new task
arrivesarrivesproblem: a task may stay at the end of the routeproblem: a task may stay at the end of the route
• Periodic controlPeriodic controltime horizon (length?)time horizon (length?)
Combination 3 Combination 3 Separated/think-ahead (2)Separated/think-ahead (2)
• Centralized controlCentralized control
b. with time horizonsb. with time horizons– Simulated annealingSimulated annealing
machine 1
machine 2
machine 3
machine 1
machine 2
machine 3
machine 1
machine 2
machine 3
loaded tripempty trip
loaded tripempty trip
loaded tripempty trip
Combination 4 Combination 4 Integrated/think-aheadIntegrated/think-ahead
AGV’s ~ parallel machinesAGV’s ~ parallel machines
empty travel time ~ change-over timeempty travel time ~ change-over time
transportation time ~ machine timetransportation time ~ machine time
Shop-floor schedulingShop-floor scheduling
Basic conceptBasic concept
Case studyCase study
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