6
Process Selection and Facility Layout
McGraw-Hill/Irwin Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved.

 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

 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

 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
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• Key aspects of process strategy
– Capital intensive – equipment/labor
– Process flexibility
– Technology
– Adjust to changes
– Design
– Volume
– technology
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 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.
6-6

 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
6-7

Technology Competitive
Advantage
 Innovations in
 Products and services
 Cell phones
 PDAs
 Wireless computing
 Processing technology
 Increasing productivity
 Increasing quality
 Lowering costs
6-8

 Variety
 How much
 Flexibility
 What degree
 Volume
 Expected output
Job Shop
Batch
Repetitive
Continuous
6-9

 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
6-10

Figure 6.2
Process Type
Job Shop Appliance repair
Emergency room
Batch Commercial baking
Classroom
Lecture
Repetitive Automotive assembly
Automatic carwash
Continuous
(flow)
Steel Production
Water purification
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Figure 6.2 (cont’d)
Dimension
Job variety
Process flexibility
Unit cost
Volume of output
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 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
6-13

 Automation : Machinery that has sensing and control devices that enables it to operate
 Fixed automation
 Programmable automation
6-14

• Computer-aided design and manufacturing systems (CAD/CAM)
• Numerically controlled (NC) machines
• Robot
• Manufacturing cell
• Flexible manufacturing systems(FMS)
• Computer-integrated manufacturing (CIM)
6-15

 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
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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
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 Requires substantial investments of money and effort
 Involves long-term commitments
 Has significant impact on cost and efficiency of short-term operations
6-18

The Need for Layout Decisions
Inefficient operations
For Example:
High Cost
Bottlenecks
Changes in the design of products or services
The introduction of new products or services
Accidents
Safety hazards
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(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
6-20


 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
Combination layouts
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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
Material and/or labor
Station
4
Finished item
Used for Repetitive or Continuous Processing
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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
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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
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Figure 6.6
In 1 2 3 4
5
Workers
6
Out 10 9 8 7
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Figure 6.7
Dept. A
Process Layout
(functional)
Dept. C Dept. E
Dept. B Dept. D Dept. F
Used for Intermittent processing
Job Shop or Batch Processes
6-26

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
6-27

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 involved 6-28

 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
6-29

 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
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Table 6.3
Functional vs. Cellular Layouts
Functional Cellular Dimension
Number of moves between departments
Travel distances
Travel paths
Job waiting times
Throughput time
Amount of work in process
Supervision difficulty
Scheduling complexity
Equipment utilization
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 Warehouse and storage layouts
 Retail layouts
 Office layouts
 Service layouts must be aesthetically pleasing as well as functional
6-32

Line Balancing is the process of assigning tasks to workstations in such a way that the workstations have approximately equal time requirements.
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Cycle time is the maximum time allowed at each workstation to complete its set of tasks on a unit.
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Output rate =
OT
CT
OT
 operating time per day
D = Desired output rate
CT = cycle time =
OT
D
6-35

Determine the Minimum Number of Workstations Required
N =
(

CT t)
 t = sum of task time
6-36

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
A Simple Precedence
Diagram
0.7 min.
c d
0.5 min.
e
0.2 min.
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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
6-38

Workstation
1
2
Time
Remaining Eligible
1.0
0.9
0.2
a, c c none
1.0
b
3 1.0
0.5
0.3
d e
d e
a c
Assign
Task b
Revised
Time
Remaining
0.9
0.2
0.0
0.5
0.3
Station
Idle Time
0.2
0.0
0.3
0.5
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Percent idle time =
Idle time per cycle
(N)(CT)
Efficiency = 1 – Percent idle time
6-40

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.
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0.2
a
0.2
b
0.8
c
0.6
d
0.3
e f
1.0
g h
0.4
0.3
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Station 1 a b c
Station 2 Station 3 e f d
Station 4 g h
6-43

1 min.
30/hr.
1 min.
30/hr.
2 min.
Bottleneck
30/hr.
1 min.
30/hr.
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30/hr.
2 min.
1 min.
60/hr.
1 min.
Parallel Workstations
30/hr.
2 min.
30/hr.
30/hr.
1 min.
60/hr.
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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
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Example 3: Interdepartmental Work
Flows
Figure 6.13
for Assigned Departments
1
30
170
3
10
0
2
A B C
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