6
Process Selection
and Facility Layout
McGraw-Hill/Irwin
Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved.
Learning Objectives





Explain the strategic importance of process
selection.
Explain the influence that process selection
has on an organization.
Describe the basic processing types.
Discuss automated approaches to
processing.
Explain the need for management of
technology.
6-2
Learning Objectives





List some reasons for redesign of layouts.
Describe the basic layout types.
List the main advantages and
disadvantages of product layouts and
process layouts.
Solve simple line-balancing problems.
Develop simple process layouts.
6-3
Introduction
 Process selection
 Deciding on the way production of goods or
services will be organized
 Major implications




Capacity planning
Layout of facilities
Equipment
Design of work systems
6-4
Figure 6.1
Process Selection and
System Design
Forecasting
Capacity
Planning
Product and
Service Design
Technological
Change
Facilities and
Equipment
Layout
Process
Selection
Work
Design
6-5
Process Strategy
• Key aspects of process strategy
–
Capital intensive – equipment/labor
–
Process flexibility
–
Technology
–
Adjust to changes
–
Design
–
Volume
–
technology
6-6
Technology
 Technology: The application of scientific
discoveries to the development and
improvement of products and services and
operations processes.
 Technology innovation: The discovery and
development of new or improved products,
services, or processes for producing or
providing them.
6-7
Kinds of Technology
 Operations management is primarily
concerned with three kinds of technology:
 Product and service technology
 Process technology
 Information technology
 All three have a major impact on:
 Costs
 Productivity
 Competitiveness
6-8
Technology Competitive
Advantage
 Innovations in
 Products and services
 Cell phones
 PDAs
 Wireless computing
 Processing technology
 Increasing productivity
 Increasing quality
 Lowering costs
6-9
Technology Acquisition
 Technology can have benefits but …
 Technology risks include:
 What technology will and will not do
 Technical issues
 Economic issues
 Initial costs, space, cash flow, maintenance
 Consultants and/or skilled employees
 Integration cost, time resources
 Training, safety, job loss
6-10
Process Selection
 Variety
Batch
 How much
 Flexibility
 What degree
Job Shop
Repetitive
 Volume
 Expected output
Continuous
6-11
Process Types
 Job shop
 Small scale
 Batch
 Moderate volume
 Repetitive/assembly line
 High volumes of standardized goods or
services
 Continuous
 Very high volumes of non-discrete goods
6-12
Figure 6.2
Product and Service
Processes
Process Type
Job Shop
Appliance repair
Emergency
room
Ineffective
Commercial
baking
Batch
Classroom
Lecture
Automotive
assembly
Repetitive
Automatic
carwash
Continuous
(flow)
Ineffective
Steel Production
Water purification
6-13
Product – Process Matrix
Figure 6.2 (cont’d)
Dimension
Job variety
Very High
Moderate
Low
Very low
Process
flexibility
Very High
Moderate
Low
Very low
Unit cost
Very High
Moderate
Low
Very low
Volume of
output
Very High
Low
High
Very low
6-14
Product and Process Profiling
 Process selection can involve substantial
investment in
 Equipment
 Layout of facilities
 Product profiling: Linking key product or service
requirements to process capabilities
 Key dimensions





Range of products or services
Expected order sizes
Pricing strategies
Expected schedule changes
Order winning requirements
6-15
Automation
 Automation: Machinery that has sensing
and control devices that enables it to
operate
 Fixed automation
 Programmable automation
6-16
Automation
• Computer-aided design and
manufacturing systems (CAD/CAM)
• Numerically controlled (NC) machines
• Robot
• Manufacturing cell
• Flexible manufacturing systems(FMS)
• Computer-integrated manufacturing (CIM)
6-17
Facilities Layout
 Layout: the configuration of
departments, work centers, and
equipment, with particular emphasis on
movement of work (customers or
materials) through the system
 Product layouts
 Process layouts
 Fixed-Position layout
 Combination layouts
6-18
Objective of Layout Design
1. Facilitate attainment of product or service
quality
2. Use workers and space efficiently
3. Avoid bottlenecks
4. Minimize unnecessary material handling
costs
5. Eliminate unnecessary movement of
workers or materials
6. Minimize production time or customer
service time
7. Design for safety
6-19
Importance of Layout
Decisions
 Requires substantial investments of
money and effort
 Involves long-term commitments
 Has significant impact on cost and
efficiency of short-term operations
6-20
The Need for Layout Decisions
Inefficient operations
For Example:
High Cost
Bottlenecks
Changes in the design
of products or services
Accidents
The introduction of new
products or services
Safety hazards
6-21
The Need for Layout Design
(Cont’d)
Changes in
environmental
or other legal
requirements
Changes in volume of
output or mix of
products
Morale problems
Changes in methods
and equipment
6-22
Basic Layout Types
 Product layouts
 Process layouts
 Fixed-Position layout
 Combination layouts
6-23
Basic Layout Types
 Product layout

Layout that uses standardized processing
operations to achieve smooth, rapid, highvolume flow
 Process layout

Layout that can handle varied processing
requirements
 Fixed Position layout

Layout in which the product or project
remains stationary, and workers, materials,
and equipment are moved as needed
6-24
Product Layout
Figure 6.4
Raw
materials
or customer
Material
and/or
labor
Station
1
Material
and/or
labor
Station
2
Material
and/or
labor
Station
3
Station
4
Finished
item
Material
and/or
labor
Used for Repetitive or Continuous Processing
6-25
Advantages of Product Layout

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
High rate of output
Low unit cost
Labor specialization
Low material handling cost
High utilization of labor and equipment
Established routing and scheduling
Routing accounting and purchasing
6-26
Disadvantages of Product Layout
 Creates dull, repetitive jobs
 Poorly skilled workers may not maintain
equipment or quality of output
 Fairly inflexible to changes in volume
 Highly susceptible to shutdowns
 Needs preventive maintenance
 Individual incentive plans are
impractical
6-27
A U-Shaped Production Line
Figure 6.6
In
1
2
3
4
5
Workers
6
Out
10
9
8
7
6-28
Process Layout
Figure 6.7
Process Layout
(functional)
Dept. A
Dept. C
Dept. E
Dept. B
Dept. D
Dept. F
Used for Intermittent processing
Job Shop or Batch Processes
6-29
Product Layout
Figure 6.7 (cont’d)
Product Layout
(sequential)
Work
Station 1
Work
Station 2
Work
Station 3
Used for Repetitive Processing
Repetitive or Continuous Processes
6-30
Advantages of Process Layouts
 Can handle a variety of processing
requirements
 Not particularly vulnerable to equipment
failures
 Equipment used is less costly
 Possible to use individual incentive
plans
6-31
Disadvantages of Process
Layouts





In-process inventory costs can be high
Challenging routing and scheduling
Equipment utilization rates are low
Material handling slow and inefficient
Complexities often reduce span of
supervision
 Special attention for each product or
customer
 Accounting and purchasing are more
6-32
Fixed Position Layouts
 Fixed Position Layout: Layout in which the
product or project remains stationary, and
workers, materials, and equipment are
moved as needed.
 Nature of the product dictates this type of
layout
 Weight
 Size
 Bulk
 Large construction projects
6-33
Cellular Layouts
 Cellular Production

Layout in which machines are grouped into
a cell that can process items that have
similar processing requirements
 Group Technology

The grouping into part families of items with
similar design or manufacturing
characteristics
6-34
Functional vs. Cellular Layouts
Table 6.3
Dimension
Functional
Cellular
Number of moves
between departments
many
few
Travel distances
longer
shorter
Travel paths
variable
fixed
Job waiting times
greater
shorter
Throughput time
higher
lower
Amount of work in
process
higher
lower
Supervision difficulty
higher
lower
Scheduling complexity
higher
lower
Equipment utilization
lower
higher
6-35
Service Layouts




Warehouse and storage layouts
Retail layouts
Office layouts
Service layouts must be aesthetically
pleasing as well as functional
6-36
Design Product Layouts: Line
Balancing
Line Balancing is the process of assigning
tasks to workstations in such a way that
the workstations have approximately
equal time requirements.
6-37
Cycle Time
Cycle time is the maximum time
allowed at each workstation to
complete its set of tasks on a unit.
6-38
Determine Maximum Output
OT
Output rate =
CT
OT  operating time per day
D = Desired output rate
OT
CT = cycle time =
D
6-39
Determine the Minimum Number
of Workstations Required
N=
(  t)
CT
 t = sum of task time
6-40
Precedence Diagram
Figure 6.11
Precedence diagram: Tool used in line balancing to
display elemental tasks and sequence requirements
0.1 min.
1.0 min.
a
b
c
0.7 min.
d
0.5 min.
A Simple Precedence
Diagram
e
0.2 min.
6-41
Example 1: Assembly Line
Balancing
 Arrange tasks shown in Figure 6.10
into three workstations.


Use a cycle time of 1.0 minute
Assign tasks in order of the most number
of followers
6-42
Example 1 Solution
Eligible
Revised
Assign Time
Task
Remaining
1.0
0.9
0.2
a, c
c
none
a
c
-
0.9
0.2
2
1.0
b
b
0.0
3
1.0
0.5
0.3
d
e
-
d
e
-
0.5
0.3
Time
Workstation Remaining
1
Station
Idle Time
0.2
0.0
0.3
0.5
6-43
Calculate Percent Idle Time
Idle time per cycle
Percent idle time =
(N)(CT)
Efficiency = 1 – Percent idle time
6-44
Line Balancing Rules
Some Heuristic (intuitive) Rules:
 Assign tasks in order of most following
tasks.
 Count the number of tasks that follow
 Assign tasks in order of greatest
positional weight.

Positional weight is the sum of each task’s
time and the times of all following tasks.
6-45
Example 2
0.2
0.2
0.3
a
b
e
0.8
0.6
c
d
f
g
h
1.0
0.4
0.3
6-46
Solution to Example 2
Station 1
a
b
Station 2
Station 3
e
f
c
Station 4
g
h
d
6-47
Bottleneck Workstation
1 min.
30/hr.
1 min.
30/hr.
2 min.
30/hr.
1 min.
30/hr.
Bottleneck
6-48
Parallel Workstations
30/hr.
1 min.
60/hr.
2 min.
30/hr.
1 min.
1 min.
60/hr.
30/hr.
2 min.
30/hr.
Parallel Workstations
6-49
Designing Process Layouts
Information Requirements:
1. List of departments
2. Projection of work flows
3. Distance between locations
4. Amount of money to be invested
5. List of special considerations
6. Location of key utilities
6-50
Example 3: Interdepartmental Work
Flows
Figure 6.13
for Assigned Departments
30
1
A
170
B
3
10
0
2
C
6-51
 PowerPoint Author’s note:
 The following three slides are not in the 9e
text, but I like to use them for alternate
examples.
6-52
Process Layout
Milling
Assembly
& Test
Grinding
Drilling
Plating
Process Layout - work travels
to dedicated process centers
6-53
Functional Layout
222
444
Mill
111 333
111
333
Lathes
222
111
444
222
Drill
Grind
3333
1111 2222
Heat
treat
Assembly
111
Gear
cutting
111
444
6-54
-1111
Lathe
Mill
Drill
222222222
Mill
3333333333
Lathe Mill
44444444444444
Drill
Mill
Heat
treat
Gear
-1111
cut
Heat
treat
Grind - 2222
Heat
treat
Grind - 3333
Drill
Gear - 4444
cut
Assembly
Cellular Manufacturing Layout
6-55
Video: Process Design
6-56
Video: Process Implementation
6-57
Video: Process Mapping
6-58