Capacity and Facilities Planning.
Chapter 7
Capacity and Facilities
Planning
1
Lecture Outline
• Capacity Planning
• Basic Layouts
• Designing Process Layouts
• Designing Service Layouts
• Designing Product Layouts
• Hybrid Layouts
Copyright 2011 John Wiley & Sons, Inc. 7-2
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)
Copyright 2011 John Wiley & Sons, Inc. 7-3
Capacity Expansion Strategies
Copyright 2011 John Wiley & Sons, Inc. 7-4
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
Copyright 2011 John Wiley & Sons, Inc. 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
Copyright 2011 John Wiley & Sons, Inc. 7-6
Best Operating Level for a Hotel
Copyright 2011 John Wiley & Sons, Inc. 7-7
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
Copyright 2011 John Wiley & Sons, Inc. 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
Copyright 2011 John Wiley & Sons, Inc. 7-9
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
Copyright 2011 John Wiley & Sons, Inc. 7-10
Process Layout in Services
Copyright 2011 John Wiley & Sons, Inc. 7-11
| Women’s lingerie |
Shoes | Housewares |
| Women’s dresses |
Cosmetics and jewelry |
Children’s department |
| Women’s sportswear |
Entry and display area |
Men’s department |
Manufacturing Process Layout
Copyright 2011 John Wiley & Sons, Inc. 7-12
A Product Layout
Copyright 2011 John Wiley & Sons, Inc. 7-13
In
Out
| • Description • Type of process • Product • Demand • Volume • Equipment |
Sequential arrangement of activities Continuous, mass production, mainly assembly Standardized, made to stock Stable High Special purpose |
Functional grouping of activities Intermittent, job shop, batch production, mainly fabrication Varied, made to order Fluctuating Low General purpose |
| Process | Product |
Copyright 2011 John Wiley & Sons, Inc. 7-14
Comparison of Product
and Process Layouts
| • Workers • Inventory • Storage space • Material handling • Aisles • Scheduling • Layout decision • Goal • Advantage |
Limited skills Low in-process, high finished goods Small Fixed path (conveyor) Narrow Part of balancing Line balancing Equalize work at each station Efficiency |
Varied skills High in-process, low finished goods Large Variable path (forklift) Wide Dynamic Machine location Minimize material handling cost Flexibility |
| Process | Product |
Copyright 2011 John Wiley & Sons, Inc. 7-15
Comparison of Product
and Process Layouts
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
Copyright 2011 John Wiley & Sons, Inc. 7-17
Block Diagramming
• Unit load
• quantity in which
material is normally
moved
• Nonadjacent load
• distance farther
than the next block
• Steps
• create load summary chart
• calculate composite (two
way) movements
• develop trial layouts
minimizing number of
nonadjacent loads
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Copyright 2011 John Wiley & Sons, Inc. 7-19
Block Diagramming: Example
| Department 1 2 3 4 5 |
| Load Summary Chart FROM/TO DEPARTMENT |
| 1 — 100 50 2 — 200 50 3 60 — 40 50 4 100 — 60 5 50 — |
1 2 3
4 5
Block Diagramming: Example
Copyright 2011 John Wiley & Sons, Inc. 7-20
| 2 3 2 4 1 3 1 2 4 5 3 5 2 5 3 4 1 4 1 5 |
200 loads 150 loads 110 loads 100 loads 60 loads 50 loads 50 loads 40 loads 0 loads 0 loads |
1 2 3
4 5
| 100 | 200 |
150
50 50
60
40
110
Grid 1
Nonadjacent Loads
110+40=150
Block Diagramming: Example
Copyright 2011 John Wiley & Sons, Inc. 7-21
| 2 3 2 4 1 3 1 2 4 5 3 5 2 5 3 4 1 4 1 5 |
200 loads 150 loads 110 loads 100 loads 60 loads 50 loads 50 loads 40 loads 0 loads 0 loads |
1 2
3
4 5
| 100 | 150 | |
| 200 110 |
50 50 40 |
60 |
Grid 2
Nonadjacent Loads: 0
• Block Diagram
• type of schematic layout diagram; includes space requirements
Copyright 2011 John Wiley & Sons, Inc. 7-22
| 1 2 |
4 |
| 3 | 5 |
3 2
5
1 4
(a) Initial block diagram (b) Final block diagram
Block Diagramming: Example
Block Diagramming With Excel
Copyright 2011 John Wiley & Sons, Inc. 7-23
Input load summary
chart and trial layout
Try different layout
configurations
Excel will calculate
composite movements
and nonadjacent loads
Relationship Diagramming
• Schematic diagram that uses
weighted lines to denote
location preference
• Muther’s grid
format for displaying manager
preferences for department
locations
Copyright 2011 John Wiley & Sons, Inc. 7-24
Copyright 2011 John Wiley & Sons, Inc. 7-25
Production
Offices
Stockroom
Shipping and
receiving
Locker room
Toolroom
A A
A
O
O
O
O
O
U
U
U
E U
I X
| A | Absolutely necessary |
| E | Especially important |
| I | Important |
O Okay
U Unimportant
X Undesirable
Relationship Diagramming
Copyright 2011 John Wiley & Sons, Inc. 7-26
(a) Relationship diagram of original layout
Key: A
E I O U X
Offices
Stockroom
Locker
room
| Toolroom |
Shipping
and
receiving
Production
Relationship Diagramming
(b) Relationship diagram of revised layout
Relationship Diagramming
Copyright 2011 John Wiley & Sons, Inc. 7-27
Offices
Stockroom
| Locker room Shipping and receiving |
Toolroom
Production Key: A
E I O U X
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
Copyright 2011 John Wiley & Sons, Inc. 7-28
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
Copyright 2011 John Wiley & Sons, Inc. 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
Copyright 2011 John Wiley & Sons, Inc. 7-31
Cycle Time Example
Copyright 2011 John Wiley & Sons, Inc. 7-32
C
d =
production time available
desired units of output
C
d =
(8 hours x 60 minutes / hour)
(120 units)
C
d = = 4 minutes
480
120
Flow Time vs Cycle Time
• Cycle time = max time spent at any station
• Flow time = time to complete all stations
Copyright 2011 John Wiley & Sons, Inc. 7-33
| 1 |
2 3
4 minutes 4 minutes 4 minutes
Flow time = 4 + 4 + 4 = 12 minutes
Cycle time = max (4, 4, 4) = 4 minutes
Efficiency of Line and Balance Delay
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j
i = 1
ti
nC
a
E =
j
i = 1
ti
C
d
N =
Efficiency Min# of workstations
where
t
i = completion time for element i
j = number of work elements
n = actual number of workstations
C
a = actual cycle time
C
d = desired cycle time
Balance delay
total idle time of line = nC
a –
Copyright 2011 John Wiley & Sons, Inc.
j
i = 1
t
i
Line Balancing Procedure
1. Draw and label a precedence diagram
2. Calculate desired cycle time required for line
3. Calculate theoretical minimum number of workstations
4. 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.
Copyright 2011 John Wiley & Sons, Inc. 7-35
Line Balancing
Copyright 2011 John Wiley & Sons, Inc. 7-36
0.1
0.2
0.4
D 0.3
B C
A
Work Element Precedence Time (Min)
A Press out sheet of fruit — 0.1
B Cut into strips A 0.2
C Outline fun shapes A 0.4
D Roll up and package B, C 0.3
Line Balancing
Copyright 2011 John Wiley & Sons, Inc. 7-37
C
d = = = 0.4 minute
40 hours x 60 minutes / hour
6,000 units
2400
6000
N = = = 2.5 3 workstations
1.0
0.4
0.1 + 0.2 + 0.3 + 0.4
0.4
Work Element Precedence Time (Min)
A Press out sheet of fruit — 0.1
B Cut into strips A 0.2
C Outline fun shapes A 0.4
D Roll up and package B, C 0.3
Line Balancing
Copyright 2011 John Wiley & Sons, Inc. 7-38
C
d = 0.4
N = 2.5
0.1
0.2
0.4
0.3
D
B C
A
Remaining Remaining
Workstation Element Time Elements
1 A 0.3 B, C
B 0.1 C, D
2 C 0.0 D
3 D 0.1 none
Line Balancing
Copyright 2011 John Wiley & Sons, Inc. 7-39
| A, B | C | D |
Work
station 1
Work
station 2
Work
station 3
0.3
minute
0.4
minute
0.3
minute
C
d = 0.4
N = 2.5
| E = = = 0.833 = 83.3% | |
| 0.1 + 0.2 + 0.3 + 0.4 | 1.0 |
| 3(0.4) | 1.2 |
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
Copyright 2011 John Wiley & Sons, Inc. 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
Copyright 2011 John Wiley & Sons, Inc. 7-41
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
Copyright 2011 John Wiley & Sons, Inc. 7-42
Parts Families
Copyright 2011 John Wiley & Sons, Inc. 7-43
A family of
similar parts
A family of related
grocery items
Original Process Layout
Copyright 2011 John Wiley & Sons, Inc. 7-44
| A B C Raw materials | |
| Assembly | |
| 1 2 3 |
10 11 12 |
| 4 5 6 |
7 8 9 |
Part Routing Matrix
Copyright 2011 John Wiley & Sons, Inc. 7-45
| Machines 1 2 3 4 5 6 7 8 9 10 11 12 |
Parts |
| A B C D E F G H |
x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x |
Figure 5.8
Revised Cellular Layout
Copyright 2011 John Wiley & Sons, Inc. 7-46
| 9 6 3 2 1 4 8 10 5 7 11 12 Cell 1 Cell 2 Cell 3 |
| Assembly |
| A B C Raw materials |
Reordered Routing Matrix
Copyright 2011 John Wiley & Sons, Inc. 7-47
| Machines 1 2 4 8 10 3 6 9 5 7 11 12 |
Parts |
| A D F |
x x x x x x x x x x x x x |
| C G |
|
| B H E |
x x x
x x x x
x x x x
x x x
x x x
Copyright 2011 John Wiley & Sons, Inc. 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
• Disadvantages
• Inadequate part families
• Poorly balanced cells
• Expanded training and
scheduling of workers
• Increased capital
investment
Copyright 2011 John Wiley & Sons, Inc. 7-49
Automated Manufacturing Cell
Copyright 2011 John Wiley & Sons, Inc. 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
Copyright 2011 John Wiley & Sons, Inc. 7-51
Fully-Implemented FMS
Copyright 2011 John Wiley & Sons, Inc. 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
Copyright 2011 John Wiley & Sons, Inc. 7-53
Balancing U-Shaped Lines
Copyright 2011 John Wiley & Sons, Inc.
A B C
D E
Precedence diagram:
Cycle time = 12 min
A,B C,D E
(a) Balanced for a straight line
9 min 12 min 3 min
| Efficiency = = = . 6666 = 66.7 % | |
| 24 | 24 |
| 36 | 3(12) |
12 min 12 min
C,D
| A,B |
| E |
(b) Balanced for a U-shaped line
| 24 | 24 |
| 24 | 2(12) |
| Efficiency = = = 100 % |
7-54
Copyright 2011 John Wiley & Sons, Inc. 7-55
Copyright 2011 John Wiley & Sons, Inc.
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Capacity and Facilities Planning
