Chapter 7
Capacity and Facilities
1
Lecture Outline
•
•
•
•
•
•
Capacity Planning
Basic Layouts
Designing Process Layouts
Designing Service Layouts
Designing Product Layouts
Hybrid Layouts
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Capacity
• Maximum capability to produce
• Capacity planning
• establishes overall level of productive
resources for a firm
• 3 basic strategies for timing of capacity
expansion in relation to steady growth in
demand (lead, lag, and average)
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Capacity Expansion Strategies
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Capacity
• Capacity increase depends on
• volume and certainty of anticipated demand
• strategic objectives
• costs of expansion and operation
• Best operating level
• % of capacity utilization that minimizes unit costs
• Capacity cushion
• % of capacity held in reserve for unexpected
occurrences
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7-5
Economies of Scale
• Unit cost decreases as output volume increases
• fixed costs can be spread over a larger number of
units
• production or operating costs do not increase linearly
with output levels
• quantity discounts are available for material
purchases
• operating efficiency increases as workers gain
experience
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Best Operating Level for a Hotel
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Objectives of Facility Layout
• Minimize material-handling costs
• Utilize space efficiently
• Utilize labor efficiently
• Eliminate bottlenecks
• Facilitate communication and interaction
• Reduce manufacturing cycle time
• Reduce customer service time
• Eliminate wasted or redundant movement
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7-8
Objectives of Facility Layout
• Facilitate entry, exit, and placement of material,
products, and people
• Incorporate safety and security measures
• Promote product and service quality
• Encourage proper maintenance activities
• Provide a visual control of activities
• Provide flexibility to adapt to changing conditions
• Increase capacity
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Basic Layouts
• Process layouts
• group similar activities together according to process
or function they perform
• Product layouts
• arrange activities in line according to sequence of
operations for a particular product or service
• Fixed-position layouts
• are used for projects in which product cannot be
moved
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7-10
Process Layout in Services
Women’s
lingerie
Shoes
Housewares
Women’s
dresses
Cosmetics
and jewelry
Children’s
department
Women’s
sportswear
Entry and
display area
Men’s
department
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7-11
Manufacturing Process Layout
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A Product Layout
In
Out
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Comparison of Product
and Process Layouts
• Description
• Type of process
• Product
• Demand
• Volume
• Equipment
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Product
Process
 Sequential
arrangement of
activities
 Continuous, mass
production, mainly
assembly
 Functional
grouping of
activities
 Intermittent, job
shop, batch
production, mainly
fabrication
 Varied, made to
order
 Fluctuating
 Low
 General purpose
 Standardized,
made to stock
 Stable
 High
 Special purpose
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Comparison of Product
and Process Layouts
Product
• Workers
• Inventory
 Limited skills
 Low in-process, high
finished goods
• Storage space
 Small
• Material handling  Fixed path (conveyor)
• Aisles
 Narrow
• Scheduling
 Part of balancing
• Layout decision  Line balancing
• Goal
 Equalize work at each
station
• Advantage
 Efficiency
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Process
 Varied skills
 High in-process, low
finished goods
 Large
 Variable path (forklift)
 Wide
 Dynamic
 Machine location
 Minimize material
handling cost
 Flexibility
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Fixed-Position Layouts
•
•
•
•
•
•
•
Typical of projects
Fragile, bulky, heavy items
Equipment, workers & materials brought to site
Low equipment utilization
Highly skilled labor
Typically low fixed cost
Often high variable costs
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Designing Process Layouts
• Goal: minimize material handling costs
• Block Diagramming
• minimize nonadjacent loads
• use when quantitative data is available
• Relationship Diagramming
• based on location preference between areas
• use when quantitative data is not available
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Block Diagramming
• Unit load
• quantity in which
material is normally
moved
• Nonadjacent load
• distance farther
than the next block
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• Steps
• create load summary chart
• calculate composite (two
way) movements
• develop trial layouts
minimizing number of
nonadjacent loads
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Block Diagramming: Example
Load Summary Chart
1
4
2
3
5
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FROM/TO
DEPARTMENT
Department
1
2
3
1
2
3
4
5
—
100
—
50
200
—
60
100
50
4
50
40
—
5
50
60
—
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Block Diagramming: Example
2
2
1
1
4
3
2
3
1
1
3
4
3
2
5
5
5
4
4
5
200 loads
150 loads
110 loads
100 loads
60 loads
50 loads
50 loads
40 loads
0 loads
0 loads
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Nonadjacent Loads
110+40=150
110
1
100
150
4
Grid 1
60
2
50
200
3
50
5
40
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Block Diagramming: Example
2
2
1
1
4
3
2
3
1
1
3
4
3
2
5
5
5
4
4
5
200 loads
150 loads
110 loads
100 loads
60 loads
50 loads
50 loads
40 loads
0 loads
0 loads
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Nonadjacent Loads: 0
1
100
2
150
200 50
40 60
110
3
4
50
5
Grid 2
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Block Diagramming: Example
• Block Diagram
• type of schematic layout diagram; includes space requirements
(a) Initial block diagram
1
(b) Final block diagram
2
4
3
5
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1
4
2
3
5
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Block Diagramming With Excel
Input load summary
chart and trial layout
Try different layout
configurations
Excel will calculate
composite movements
and nonadjacent loads
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Relationship Diagramming
• Schematic diagram that uses
weighted lines to denote
location preference
• Muther’s grid
format for displaying manager
preferences for department
locations
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Relationship Diagramming
A
E
I
O
U
X
Production
O
A
Offices
U
Shipping and
receiving
I
E
O
Stockroom
Absolutely necessary
Especially important
Important
Okay
Unimportant
Undesirable
A
A
X
U
U
U
O
O
Locker room
O
Toolroom
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7-25
Relationship Diagramming
(a) Relationship diagram of original layout
Offices
Stockroom
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Locker
room
Toolroom
Shipping
and
receiving
Production
Key: A
E
I
O
U
X
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Relationship Diagramming
(b) Relationship diagram of revised layout
Stockroom
Shipping
and
receiving
Offices
Toolroom
Production
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Locker
room
Key: A
E
I
O
U
X
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Computerized Layout Solutions
• CRAFT
• Computerized Relative Allocation of Facilities Technique
• CORELAP
• Computerized Relationship Layout Planning
• PROMODEL and EXTEND
• visual feedback
• allow user to quickly test a variety of scenarios
• Three-D modeling and CAD
• integrated layout analysis
• available in VisFactory and similar software
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Designing Service Layouts
• Must be both attractive and functional
• Free flow layouts
• encourage browsing, increase impulse purchasing,
are flexible and visually appealing
• Grid layouts
• encourage customer familiarity, are low cost, easy
to clean and secure, and good for repeat customers
• Loop and Spine layouts
• both increase customer sightlines and exposure to
products, while encouraging customer to circulate
through the entire store
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Types of Store Layouts
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7-30
Designing Product Layouts
• Objective
• Balance the assembly line
• Line balancing
• tries to equalize the amount of work at each
workstation
• Precedence requirements
• physical restrictions on the order in which operations
are performed
• Cycle time
• maximum amount of time a product is allowed to
spend at each workstation
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7-31
Cycle Time Example
production time available
desired units of output
Cd =
Cd =
(8 hours x 60 minutes / hour)
(120 units)
Cd =
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480
120
= 4 minutes
7-32
Flow Time vs Cycle Time
• Cycle time = max time spent at any station
• Flow time = time to complete all stations
1
2
3
4 minutes
4 minutes
4 minutes
Flow time = 4 + 4 + 4 = 12 minutes
Cycle time = max (4, 4, 4) = 4 minutes
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7-33
Efficiency of Line and Balance Delay
Efficiency
Min# of workstations
j
t
E=
where
i=1
nCa
ti
j
n
Ca
Cd
j
t
i
N=
i
i=1
Cd
= completion time for element i
= number of work elements
= actual number of workstations
= actual cycle time
= desired cycle time
Balance delay
total idle time of line = nCa -
j
t
i=1
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i
7-34
Line Balancing Procedure
1.
2.
3.
4.
Draw and label a precedence diagram
Calculate desired cycle time required for line
Calculate theoretical minimum number of workstations
Group elements into workstations, recognizing cycle
time and precedence constraints
5. Calculate efficiency of line
6. Determine if theoretical minimum number of
workstations or an acceptable efficiency level has been
reached. If not, go back to step 4.
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Line Balancing
Work Element
A
B
C
D
Precedence
Time (Min)
—
A
A
B, C
0.1
0.2
0.4
0.3
Press out sheet of fruit
Cut into strips
Outline fun shapes
Roll up and package
0.2
B
0.1 A
D 0.3
C
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0.4
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Line Balancing
Work Element
A
B
C
D
Press out sheet of fruit
Cut into strips
Outline fun shapes
Roll up and package
Precedence
Time (Min)
—
A
A
B, C
0.1
0.2
0.4
0.3
40 hours x 60 minutes / hour
2400
Cd =
=
= 0.4 minute
6,000 units
6000
0.1 + 0.2 + 0.3 + 0.4
1.0
N=
=
= 2.5  3 workstations
0.4
0.4
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Line Balancing
Workstation
Element
1
Remaining
Time
Remaining
Elements
0.3
0.1
0.0
0.1
B, C
C, D
D
none
A
B
C
D
2
3
0.2
B
0.1
A
D
C
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0.3
Cd = 0.4
N = 2.5
0.4
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Line Balancing
Work
station 1
Work
station 2
Work
station 3
A, B
C
D
0.3
minute
0.4
minute
0.3
minute
Cd = 0.4
N = 2.5
1.0
0.1 + 0.2 + 0.3 + 0.4
E=
=
= 0.833 = 83.3%
1.2
3(0.4)
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7-39
Computerized Line Balancing
• Use heuristics to assign tasks to workstations
•
•
•
•
•
Longest operation time
Shortest operation time
Most number of following tasks
Least number of following tasks
Ranked positional weight
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7-40
Hybrid Layouts
• Cellular layouts
• group dissimilar machines into work centers (called cells) that
process families of parts with similar shapes or processing
requirements
• Production flow analysis (PFA)
• reorders part routing matrices to identify families of parts with
similar processing requirements
• Flexible manufacturing system
• automated machining and material handling systems which can
produce an enormous variety of items
• Mixed-model assembly line
• processes more than one product model in one line
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Cellular Layouts
1. Identify families of parts with similar flow paths
2. Group machines into cells based on part
families
3. Arrange cells so material movement is
minimized
4. Locate large shared machines at point of use
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Parts Families
A family of
similar parts
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A family of related
grocery items
7-43
Original Process Layout
Assembly
4
6
7
8
5
2
A
B
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12
10
3
1
9
C
11
Raw materials
7-44
Part Routing Matrix
Parts
1
2
A
B
C
D
E
F
G
H
x
x
3
Machines
4 5 6 7
8 9 10 11 12
x
x
x
x
x
x
x
Figure
5.8
Copyright
2011 John Wiley & Sons, Inc.
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
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Revised Cellular Layout
Assembly
8
10
9
12
11
4
Cell 1
Cell 2
6
Cell 3
7
2
1
3
5
A B C
Raw materials
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7-46
Reordered Routing Matrix
Parts
1
2
4
Machines
8 10 3 6
A
D
F
C
G
B
H
E
x
x
x
x
x
x
x
x
x
x
x
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9 5
7 11 12
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
7-47
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7-48
Cellular Layouts
• Advantages
• Reduced material handling
and transit time
• Reduced setup time
• Reduced work-in- process
inventory
• Better use of human
resources
• Easier to control
• Easier to automate
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• Disadvantages
• Inadequate part families
• Poorly balanced cells
• Expanded training and
scheduling of workers
• Increased capital
investment
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Automated Manufacturing Cell
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7-50
Flexible Manufacturing Systems (FMS)
• Consists of
• programmable machine tools
• automated tool changing
• automated material handling system
• controlled by computer network
• Combines flexibility with efficiency
• Layouts differ based on
• variety of parts the system can process
• size of parts processed
• average processing time required for part completion
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7-51
Fully-Implemented FMS
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7-52
Mixed Model Assembly Lines
• Produce multiple models in any order on one
assembly line
• Factors in mixed model lines
•
•
•
•
Line balancing
U-shaped lines
Flexible workforce
Model sequencing
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7-53
Balancing U-Shaped Lines
Precedence diagram:
A
B
C
D
E
Cycle time = 12 min
(a) Balanced for a straight line
(b) Balanced for a U-shaped line
A,B
C,D
E
9 min
12 min
3 min
Efficiency =
A,B
24
24
=
= .6666 = 66.7 %
3(12)
36
C,D
E
Efficiency =
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24
24
=
= 100 %
2(12)
24
12 min
12 min
7-54
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