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7/31/2019 05 Facilities Layout
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Session
5FacilityLayout
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Define layout planning and explain its importance
Identify and describe different types of layouts Compare process layouts & product layouts
Describe the steps involved in designing a process
layout
Describe the steps involved in designing a product
layout
Explain the advantages of hybrid layouts
Define the meaning of group technology (cell) layouts
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Higher utilization of space, equipment, and people
Improved flow of information, materials, or people
Improved employee morale and safer working
conditions
Improved customer/client interaction
Flexibility
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Material handling equipment
Capacity and space requirements
Environment and aesthetics
Flows of information
Cost of moving between various work areas
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The objective of layout strategy is to develop a cost-
effective layout that will meet a firms competitive
needs
Layout planning is determining the best physical
arrangement of resources within a facility
Facility resource arrangement can significantly affectproductivity
Two broad categories of operations:
Intermittent processing systems low volume of
many different products Continuous processing systems high volume of a
few standardized products
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Four basic layout types consisting of;
Process layouts Group similar resources together Product layoutsDesigned to produce a specific
product efficiently
Cell layoutsOrganizes people & machines into a
group Fixed-Position layoutsProduct is too large to
move; e.g. a building
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Equipment that perform similar processes are grouped
together
Used when the operations system must handle a wide
variety of products in relatively small volumes (i.e.,
flexibility is necessary)
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Advantages of process layouts include
general purpose & flexible resources
a lower investment in equipment, and
diversity of jobs inherent in a process layout can lead
to increased worker satisfaction.
Disadvantages include
high movement and transportation costs,
more complicated planning and control systems,
longer total processing time,
higher in-process inventory or waiting time,
higher worker-skill requirements, and Space requirements are higher.
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Operations are arranged in the sequence required to
make the product
Used when the operations system must handle a narrow
variety of products in relatively high volumes
Operations and personnel are dedicated to producing one
or a small number of products
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Advantages of product layouts include
lower work-in-process inventories,
shorter processing times,
less material handling,
lower labor skills, and
simple planning and control systems.
Disadvantages include that
a breakdown at one workstation can cause the entire
process to shut down;
a change in product design or the introduction of new
products may require major changes in the layout, limiting flexibility.
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Operations required to produce a particular family
(group) of parts are arranged in the sequence required tomake that family
Used when the operations system must handle a
moderate variety of products in moderate volumes
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The Advantages are:
Reduced work in process inventory workcell is setupto provide one piece flow from machine to machine
Less floor space required because less space is needed
between machines to keep WIP inventory
Reduced direct labor
Heightened sense of employee participation Increased use of equipment and machinery
Reduced investment in machinery and equipment
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Product remains in a fixed position, and the personnel,
material and equipment come to it
Used when the product is very bulky, large, heavy or
fragile
Complicating factors
Limited space at site
Different materialsrequired at different
stages of the project
Volume of materials
needed is dynamic
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Step 1: Gather information:
Space needed, space available, importance ofproximity (closeness) between various units
Step 2: Develop alternative block plans:
Using trial-and-error or decision support tools
Step 3: Develop a detailed layout
Consider exact sizes and shapes of departments and
work centers including aisles and stairways
Tools like drawings, 3-D models, and CAD software
are available to facilitate this process
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Step 1: Gather information like space needed, from-to
matrix, and REL Chart for Recovery First Sports MedicineClinic (total space 3750 sq. ft.)
A
Radiology
400 sq. ft.
B
Laboratory
300 sq. ft.
C
Lobby &
Waiting300 sq. ft.
D
ExaminingRooms
800 sq. ft.
E
Surgery &Recovery
900 sq. ft.
F
PhysicalTherapy
1050 sq. ft.
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TableFrom-To Matrix
for Recovery First
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TableREL Chart for
Recovery First
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Step 2: Develop A New Block Layout Use trial and error with
From-To and REL Charts asa guide
Use computer softwarelike ALDEP or CRAFT
Table : Id Score Computations for Current and Proposed Layouts for Recovery First
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Decision Support Tools
Trial and error method good for simple problems Layout problems are combinatorial,
3x2 office layout has 6! Options (6*5*4*3*2*1 =
720 options)
Computer programs are available decision supporttools
ALDEP (Automated Layout Design Program) based
on REL (Relationship Layout) and CRAFT
(Computerized Relative Allocation of Facilities
Techniques) based on form-to matrix
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There are a number of unique process layouts which
include Warehouse layouts
Office Layouts
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Objective is to optimize trade-offs between handling costs
and costs associated with warehouse space
Maximize the total cube of the warehouse utilize its
full volume while maintaining low material handling costs
Warehouse density tends to vary inversely with the
number of different items stored
Automated Storage and
Retrieval Systems (ASRSs)
can significantly improve
warehouse productivity byan estimated 500%
Dock location is a key
design element
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The usage ofCrossdockingmodifies the traditional
warehouse layouts; more docks, less storage space, andless order picking
Materials are moved directly from receiving to shipping
and are not placed in storage
in the warehouse Requires tight
scheduling and
accurate shipments,
bar code or RFIDidentification used for
advanced shipment
notification as materials
are unloaded
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Human interaction and communication are the primary
factors in designing office layouts
Layouts need to account for physical environment and
psychological needs of the organization
One key layout trade-off is between proximity and
privacy
Open concept offices promote understanding & trust
Flexible layouts incorporating
office landscaping help tosolve the privacy issue in open
office environments
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Product layouts are different than process layouts
Product layouts provide for sequential product
movement that enhances efficiency
Designing product layouts requires consideration of
Sequence of tasks to be performed by each
workstation
Logical order
Speed considerations line balancing
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Step 1: Identify tasks & immediate predecessors
Step 2: Determine the desired output rate
Step 3: Calculate the cycle time
Step 4: Compute the theoretical minimum number of
workstations
Step 5: Assign tasks to workstations (balance the line)
Step 6: Compute efficiency, idle time & balance delay
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Step 1: Identify tasks & immediate predecessors
Wiley 2007
Example 10.4 Vicki's Pizzeria and the Precedence DiagramImmediate Task Time
Work Element Task Description Predecessor (secondsA Roll dough None 50
B Place on cardboard backing A 5
C Sprinkle cheese B 25
D Spread Sauce C 15
E Add pepperoni D 12
F Add sausage D 10G Add mushrooms D 15
H Shrinkwrap pizza E,F,G 18
I Pack in box H 15
Total task time 165
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Step 2: Determine output rate
Vicki needs to produce 60 pizzas per hour
Step 3:Determine cycle time
The amount of time each workstation is allowed to
complete its tasks
Limited by the bottleneck task (the longest task in a
process):
sec./unit60units/hr60
sec/min60xmin/hr60
units/hroutputdesired
sec./daytimeavailable)(sec./unittimeCycle
hourperpizzasorunits/hr,72sec./unit50
sec./hr.3600
timetaskbottleneck
timeavailableoutputMaximum
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Step 4: Compute the theoretical minimum number of
stations TM = number of stations needed to achieve 100%
efficiency (every second is used)
Always round up (no partial workstations) Serves as a lower bound for our analysis
stations3or2.75,
nsec/statio60
seconds165
timecycle
timestaskTM
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Step 5: Assign tasks to workstations
Start at the first station & choose the longest eligibletask following precedence relationships
Continue adding the longest eligible task that fits
without going over the desired cycle time
When no additional tasks can be added within the
desired cycle time, begin assigning tasks to the next
workstation until finished
Workstation Eligible task Task Selected Task time Idle time
A A 50 10
B B 5 5C C 25 35
D D 15 20
E, F, G G 15 5
E, F E 12 48
F F 10 38
H H 18 20
I I 15 5
1
2
3
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Step 6: Compute efficiency and balance delay
Efficiency (%) is the ratio of total productive timedivided by total time
Balance delay (%) is the amount by which the line
falls short of 100%
91.7%100sec.60xstations3
sec.165
NC
t(%)Efficiency
8.3%91.7%100%delayBalance
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Shape of the line (S, U, O, L):
Share resources, enhance communication & visibility,impact location of loading & unloading
Paced versus un-paced lines
Paced lines use an automatically enforced cycle time
Number of products produced
Single
Mixed-model lines
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One of the most popular hybrid layouts uses Group
Technology (GT) and a cellular layout GThas the advantage of bringing theefficiencies of a
product layout to aprocess layout environment
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Process Flows before the Use of GT Cells
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Process Flows after the Use of GT Cells
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Layout planning is organizationally important for an
efficient operations Marketing is affected by layout especially when
clients come to the site
Human resources is affected as layout impacts
people
Finance is involved as layout changes can be costly
endeavors