© Wiley 2007 Chapter 10 Facility Layout. © Wiley 2007 OUTLINE What Is Layout Planning? Types of...
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Transcript of © Wiley 2007 Chapter 10 Facility Layout. © Wiley 2007 OUTLINE What Is Layout Planning? Types of...
© Wiley 2007
OUTLINE
What Is Layout Planning? Types of Layouts Designing Process Layouts Special Cases of Process Layouts Designing Product Layouts Designing Hybrid Layouts
© Wiley 2007
What Is Layout Planning
Layout planning is determining the best physical arrangement of resources within a facility
Facility resource arrangement can significantly affect productivity
Two broad categories of operations: Intermittent processing systems – low volume of
many different products Continuous processing systems – high volume of a
few standardized products
© Wiley 2007
Types of Layouts
Four basic layout types consisting of; Process layouts - Group similar resources
together Product layouts - Designed to produce a
specific product efficiently Hybrid layouts - Combine aspects of both
process and product layouts Fixed-Position layouts - Product is too large
to move; e.g. a building
© Wiley 2007
Process Layouts Process layout unique characteristics
include;
General purpose & flexible resources
Facilities are more labor intensive
Lower capital intensity & automation
Higher labor intensity
© Wiley 2007
Process Layouts - continued Processing rates are slower
Material handling costs are higher
Scheduling resources & work flow is more complex
Space requirements are higher
© Wiley 2007
Product Layouts
Product layout unique characteristics Produce small number of products
efficiently Resources are specialized High capital intensity Low flexibility relative to the market
© Wiley 2007
Product Layouts - continued
Processing rates are faster
Material handling costs are lower
Lower space requirements
© Wiley 2007
Hybrid Layouts Combine elements of both product &
process layouts Maintain some of the efficiencies of
product layouts Maintain some of the flexibility of process
layouts
Examples: Group technology & manufacturing cells Grocery stores
© Wiley 2007
Fixed-Position Layout
Used when product is large Product is difficult or impossible to
move, i.e. very large or fixed All resources must be brought to
the site Scheduling of crews and resources
is a challenge
© Wiley 2007
Designing Process Layouts Step 1: Gather information:
Space needed, space available, importance of proximity 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
© Wiley 2007
Process Layout Steps Step 1: Gather information like space needed, from-to
matrix, and REL Chart for Recovery First Sports Medicine Clinic (total space 3750 sq. ft.)
ARadiology
400 sq. ft.
BLaboratory
300 sq. ft.
CLobby & Waiting
300 sq. ft.
DExamining
Rooms800 sq. ft.
ESurgery & Recovery900 sq. ft.
FPhysical Therapy
1050 sq. ft.
© Wiley 2007
Step 2: Develop a New Block Layout Use trial and error with from-to or REL Charts as a guide Use computer software like ALDEP or CRAFT
© Wiley 2007
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 support tools ALDEP based on REL and CRAFT based on
form-to matrix
© Wiley 2007
Special Cases of Process Layouts
There are a number of unique process layouts which include
Warehouse layouts
Office Layouts
© Wiley 2007
Warehouse Layouts
Warehouse Layout Considerations: Primary decision is where to locate each
department relative to the dock Departments can be organized to minimize “ld”
totals Departments of unequal size require
modification of the typical ld calculations to include a calculation of the “ratio of trips to area needed”
The usage of “Crossdocking” modifies the traditional warehouse layouts; more docks, less storage space, and less order picking
© Wiley 2007
Office Layouts Office Layout Considerations:
Almost half of US workforce works in an office environment
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 to solve the privacy issue in open office environments
© Wiley 2007
Designing Product Layouts 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
© Wiley 2007
Designing Product Layouts - continued
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
© Wiley 2007
Step 1: Identify Tasks & Immediate PredecessorsExample 10.4 Vicki's Pizzeria and the Precedence Diagram
Immediate Task TimeWork Element Task Description Predecessor (seconds
A Roll dough None 50B Place on cardboard backing A 5C Sprinkle cheese B 25D Spread Sauce C 15E Add pepperoni D 12F Add sausage D 10G Add mushrooms D 15H Shrinkwrap pizza E,F,G 18I Pack in box H 15
Total task time 165
© Wiley 2007
Layout Calculations
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./unit 60
units/hr 60
sec/min 60x min/hr 60
units/hroutput desired
sec./day time available)(sec./unit time Cycle
hourper pizzasor units/hr, 72sec./unit 50
sec./hr. 3600
time task bottleneck
time availableoutput Maximum
© Wiley 2007
Layout Calculations (continued)
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
stations 3or 2.75,
nsec/statio 60
seconds 165
time cycle
times taskTM
© Wiley 2007
Layout Calculations (continued)
Step 5: Assign tasks to workstations Start at the first station & choose the longest eligible task
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 finishedWorkstation Eligible task Task Selected Task time Idle time
A A 50 10
B B 5 5
C 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
© Wiley 2007
Last Layout Calculation Step 6: Compute efficiency and balance
delay Efficiency (%) is the ratio of total
productive time divided by total time
Balance delay (%) is the amount by which the line falls short of 100%
91.7%100sec. 60x stations 3
sec. 165
NC
t (%) Efficiency
8.3%91.7%100%delay Balance
© Wiley 2007
Other Product Layout Considerations
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-model line Mixed-model line
© Wiley 2007
Designing Hybrid Layouts One of the most popular hybrid layouts uses
Group Technology (GT) and a cellular layout GT has the advantage of bringing the efficiencies
of a product layout to a process layout environment
© Wiley 2007
Facility Layout Across the Organization
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