Facility Layout

Production Plant Layout (1)Facility Layout Problem: design problemlocations of activitiesdimensionsconfigurations

No overall algorithm exists

Production Plant Layout (2)Reasons:new productschanges in demandchanges in product designnew machines bottleneckstoo large bufferstoo long transfer timesProduction Plant Layout (2)

Design

Production Plant Layout (3)Goals (examples):minimal material handling costsminimal investmentsminimal throughput timeflexibilityefficient use of space

Production Plant Layout (4)Restrictions:legislation on employees working conditionspresent building (columns/waterworks)Methods:Immer: The right equipment at the right place to permit effective processingApple: Short distances and short times

Goals Production Plant LayoutPlan for the preferred situation in the future

Layout must support objectives of the facility

No accurate data layout must be flexible

Systematic Layout Planning Muther (1961)0 Data gathering

0 - Data gathering (1)Source: product design

BOMdrawingsgozinto (assembly) chart, see fig 2.10redesign, standardization simplifications

0 - Data gathering (2)Source: Process designmake/buyequipment usedprocess timesoperations process chart (fig 2.12)

assembly chart

operations precedence diagram(fig 2.13)

0 - Data gathering (3)Source: Production schedule designlogistics: where to produce, how much product mixmarketing: demand forecast production ratetypes and number of machinescontinuous/intermittentlayout schedule

1/2 - Flow and Activity AnalysisFlow analysis:Types of flow patternsTypes of layout flow analysis approaches

Activity relationship analysis

1/2 - Flow analysis and activity analysisFlow analysisquantitative measure of movements between departments: material handling costsActivity analysisqualitative factors

Flow analysisFlow of materials, equipment and personnel

layout facilitates this flow

Types of flow patternsP = receivingS = shippingHorizontal transport

Layoutvolumes of productionvariety of products

volumes: what is the right measure of volume from a layout perspective?variety high/low commonalitylayout type

Types of layoutFixed product layoutProduct layoutGroup layoutProcess layout

Fixed product layoutProcesses product (e.g. shipbuilding)

Product layout (flow shop)Production line according to the processing sequence of the productHigh volume productionShort distances

Process layout (Job shop)All machines performing a particular process are grouped together in a processing departmentLow production volumesRapid changes in the product mixHigh interdepartmental flow

Group layoutCompromise between product layout and process layoutProduct layouts for product families cells (cellular layout)Group technology

Production volume and product variety determines type of layout

Layout determinesmaterial handlingutilization of space, equipment and personnel (table 2.2)

Flow analysis techniquesFlow process charts product layoutFrom-to-chart process layouts

Activity relationship analysis Relationship chart (figure 2.24)Qualitative factors (subjective!)Closeness rating (A, E, I, O, U or X)

3 - Relationship diagramsConstruction of relationships diagrams: diagrammingMethods, amongst others: CORELAP

Relationship diagram (1)Spatial picture of the relationships between departmentsConstructing a relation diagram often requires compromises. What is closeness? 10 or 50 meters?See figure 2.25

Relationship diagram (2)Premise:geographic proximity reflects the relationshipsSometimes other solutions:e.g. X-rating because of noise acoustical panels instead of distance separatione.g. A rating because of communication requirement computer network instead of proximity

Graph theory based approachclose adjacentdepartment-nodeadjacent-edgerequirement: graph is planar (no intersections)region-faceadjacent faces: share a common edgegraph

Primal graph dual graphPlace a node in each face Two faces which share an edge join the dual nodes by an edgeFaces dual graph correspond to the departments in primal graph block layout (plan) e.g. figure 2.39

Graph theoryPrimal graph planar dual graph planarLimitations to the use of graph theory: it may be an aid to the layout designer

CORELAPConstruction algorithm Adjacency!Total closeness rating = sum of absolute values for the relationships with a particular department.

CORELAP - stepssequence of placements of departmentslocation of departments

CORELAP step 1First department:

Second department: X-relation last placed departmentA-relation with first. If none E-relation with first, etcetera

CORELAP step 2Weighted placement value

4 - Space requirementsBuilding geometry or building site space availableDesired production rate, distinguish:Engineer to order (ETO)Production to order (PTO)Production to stock (PTS)marketing forecast productions quantities

4 - Space requirementsEquipment requirements:Production rate number of machines requiredEmployee requirements

Space determinationMethods:1. Production center2. Converting4. Standards5. Projection

4 - Space determination (1)1. Production centerfor manufacturing areasmachinespace requirements2. Convertinge.g. for storage areaspresent space requirement space requirementsnon-linear function of production quantitiy

4 - Space determination (2)Space standardsstandardsRatio trend and projection e.g. direct labour hour, unit produced

Not accurate!Include space for: packaging, storage, maintenance, offices, aisles, inspection, receiving and shipping, canteen, tool rooms, lavatories, offices, parking

Deterministic approach (1)n = # machines per operator (non-integer)a = concurrent activity timet = machine activity timeb= operator

Deterministic approach (2)Tc = cycle timea = concurrent activity timet = machine activity timeb = operator activity timem = # machines per operator

Deterministic approach (3)TC(m) = cost per unit produced as a function of mC1 = cost per operator-hourC2 = cost per machine-hour

Compare TC(n) and TC(n+1) for n < n < n+1

Designing the layout (1)Search phaseAlternative layoutsDesign process includesSpace relationship diagramBlock planDetailed layoutFlexible layoutsMaterial handling systemPresentation

Designing the layout (2)Relationship diagram + space space relationship diagram (see fig 2.56)

Different shapes

9 Layout alternativesAlternative layouts by shifting the departments to other locations block plan, also shows e.g. columns and positions of machines (see fig 2.57)

Flexible layoutsFuture Anticipate changes2 types of expansion: sizesnumber of activities

Material handling systemDesign in parallel with layoutPresentationCAD templates 2 or 3 dimensionalsimulationsselling the layout (+ evaluation)

10 Evalution (1)Selection and implementationbest layoutcost of installation + operating costcompare future costs for both the new and the old layoutother considerationsselling the layoutassess and reduce resistanceanticipate amount of resistance for each alternative

10 Evalution (2)Causes of resistance:inertiauncertaintyloss of job contentMinimize resistance byparticipationstages

ImplementationInstallationplanningPeriodic checks after installation

Systematic Layout Planning

Systematic Layout Planning

Automatic Guided Vehicles (AGVs)Unmanned vehicle for in-plant transportation on manufacturing and assembly areas

Two types of guidancefree rangingdead reckoning + lasers or transponderspath restrictedinduction wires in the floor

AGV fork lift truck with RF-communication

Design and operational control of an AGV systemAGV systemtrack layoutnumber of AGVsoperational control

Traffic control: zonesmax. throughput capacity

Track layoutinfrastructurelocation of pick-up and drop-off stationsbuffer sizescongestion/blockingtandem configuration

Determination of number of AGVsLP-problem (i.e. a classical TP)

Operational transportation controlJob control(routing and scheduling of transportation tasks)

Traffic controlTraffic rulesGoal: minimize empty travel + waiting time

Single load:Performance indicators: - Throughput - Throughput times

Operational controlproduction control transportation controlflow shopjob shopcentralized controlall tasks are concurrently consideredor decentralized controlFEFS: AGV looks for work (suited for tandem configuration)think-aheadcombine tasks to routesor no think-ahead

Relations between the issues

Combination 1 Separated/no think-aheadcentralized controlon-line priority rules:transportation task assignment tasks wait, oridle vehicle assignment idle vehicles wait

Ad 1: push/pull (JIT), e.g. FCFS, MOQRS Push sometimes shop lockingAd 2: NV, LIV

Combination 3 Separated/think-ahead (1)Centralized controla. without time windowsOnly routingMinimize empty travel time by simulated annealing:

2 options:determine optimal route each time a new task arrives problem: a task may stay at the end of the routePeriodic control time horizon (length?)

Combination 3 Separated/think-ahead (2)Centralized controlb. with time horizonsSimulated annealing

Combination 4 Integrated/think-aheadAGVs ~ parallel machinesempty travel time ~ change-over timetransportation time ~ machine time

Basic concept

Case study