© Wiley 2010 1 Chapter 10 – Facility Layout Operations Management by R. Dan Reid & Nada R. Sanders 4th Edition © Wiley 2010
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© Wiley 2010 1
Chapter 10 – Facility Layout
Operations Managementby
R. Dan Reid & Nada R. Sanders4th Edition © Wiley 2010
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Learning Objectives 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
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Learning Objectives – con’t
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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What Is Layout Planning?Layout planning is deciding the best physical
arrangement of all 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
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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 two large to move; e.g. a building
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Process Layouts Process layout unique characteristics
include:
Resources used are general purpose Facilities are less capital intensive Facilities are more labor intensive Resources have greater flexibility Processing rates are slower Material handling costs are higher
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Process Layouts – con’t
Scheduling resources & work flow is more complex
Space requirements are higher
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Product Layouts Product layout unique characteristics are:
Resources are specialized Facilities are capital intensive Processing rates are faster Material handling costs are lower Space requirements for inventory storage are
lower Flexibility is low relative to the market
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Process vs. Product Layouts
Here are the characteristic differences between a process and product layout.
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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
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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
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Designing Process LayoutsStep 1: Gather information:
Space needed, space available, identify closeness measures
Step 2: Develop alternative block plans:Using trial-and-error or decision support tools
Step 3: Develop a detailed layout:Consider exact sizes/shapes of departments and
work centers including aisles and stairwaysTools like drawings, 3-D models, and CAD
software are available to facilitate this process
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Special Cases of Process Layouts
A number of unique process layouts require special attention. We will look at two of these:
Warehouse layouts Office Layouts
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Warehouse LayoutsWarehouse 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
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Office LayoutsOffice 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
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Designing Product Layouts 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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Designing Product Layouts – con’t
Step 1: Identify tasks & immediate predecessorsStep 2: Determine output rateStep 3: Determine cycle timeStep 4: Compute the Theoretical Minimum number
of StationsStep 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 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
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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 60sec/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. 3600time task bottleneck
time availableoutput Maximum
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Layout Calculations con’t 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 60seconds 165
time cycletimes task
TM
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Layout Calculations con’t 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 finished
Workstation Eligible task Task Selected Task time Idle timeA A 50 10B B 5 5C C 25 35D D 15 20
E, F, G G 15 5E, F E 12 48
F F 10 38H H 18 20I I 15 5
1
2
3
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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. 165NC
t (%) Efficiency
8.3%91.7%100%delay Balance
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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 Product Models produced Single Mixed-model lines
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Group Technology (CELL) 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
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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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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
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Facility Layout within OM: How it all fits together
Layout decisions are directly related to issues of product design and process selection (Ch 3).
Job design, as process layouts tend to require greater worker skills than do product layouts (Ch 11).
Degree of automation, as product layouts tend to be more capital intensive and use more automation compared to process layouts (Ch 3).
Layout decisions are also affected by implementation of just-in-time (JIT) systems, which dictate a line flow and the use of group technology (GT) cells (Ch 7).
As layout decisions specify the flow of goods through the facility, they impact all other aspects of operations management.
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Chapter 10 Highlights Layout planning is deciding on the best physical
arrangement of all resources that consumes space within a facility. Proper layout planning is highly important for the efficient running of a business. Otherwise, there can be much wasted time and energy, as well as confusion.
There are four basic types of layouts: process, product, hybrid, and fixed position. Process layouts group resources based on similar processes. Product layouts arrange resources in straight-line fashion. Hybrid layouts combine elements of both process and product layouts. Fixed-position layouts occur when the product is larger and cannot be moved.
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Chapter 10 Highlights – con’t
Process layouts provide much flexibility and allow for the production of many products with differing characteristics. Product layouts, on the other hand, provide greater efficiency when producing one type of product.
The steps for designing process layouts are (1) gather information about space needs, space availability, and closeness requirements of departments; (2) developing a block plan or schematic of the layout; and (3) developing a detailed layout.
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Chapter 10 Highlights – con’t
The steps for designing an product layout are (1) identify tasks that need to be performed and their immediate predecessors; (2) determine output rate; (3) determine cycle time; (4) computing the theoretical minimum number of work stations, (5) assigning tasks to workstations; and (6) computing efficiency and balance delay.
Hybrids layouts have advantages over other layout types because they combine elements of both process and product layouts to increase efficiency.
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Chapter 10 Highlights – con’t
An example of hybrid layouts is group technology or cell layouts. Group technology is the process of crating groupings of products based on similar processing requirements. Cells are created for each grouping of products, resulting in a more orderly flow of products through the facility.
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Chapter 10 Homework Hints
10.8: Assign sites based on number of trips (refer to Example 10.2). There is no strategy regarding which side of the aisle to assign—just nearness to the dock.
10.16: Follow the steps. This is a product layout (assembly line balancing). The book has an example on pages 360-366, which is also on the slides covered in class.
Sample Problem—10.7
dock aisle
Department
Category Trips to/from
dock1 Sports t-shirts 502 Men’s t-shirts 633 Women’s t-shirts 354 Children’s t-shirts 555 Fashion t-shirts 486 Undershirts 60
Sample Problem –10.15
Draw precedence diagram Determine cycle time—demand = 50 units/hr Theoretical minimum no. of work stations Assign tasks to workstations using cycle time Efficiency and balance delay of line? Bottleneck? Maximum output?
Task Imm. predecessor Task time (sec)A None 55B A 30C A 22D B 35E B, C 50F C 15G F 5H G 10
TOTAL 222