8 - 1 chapter 9 : layout strategies. 8 - 2 outline the strategic importance of layout decisions ...
TRANSCRIPT
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Chapter 9 : Layout StrategiesChapter 9 : Layout Strategies
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Outline
The Strategic Importance of Layout Decisions
Types of Layout
Office Layout
Retail Layout
Warehousing and Storage Layouts
Fixed-Position Layout
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Outline – Continued
Process-Oriented Layout
Work Cells Requirements of Work Cells
Staffing and Balancing Work Cells
The Focused Work Center and the Focused Factory
Repetitive and Product-Oriented Layout Assembly-Line Balancing
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Work Cells
Reorganizes people and machines into groups to focus on single products or product groups
Group technology identifies products that have similar characteristics for particular cells
Volume must justify cells
Cells can be reconfigured as designs or volume changes
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Advantages of Work Cells
1. Reduced work-in-process inventory
2. Less floor space required
3. Reduced raw material and finished goods inventory
4. Reduced direct labor
5. Heightened sense of employee participation
6. Increased use of equipment and machinery
7. Reduced investment in machinery and equipment
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Requirements of Work Cells
1. Identification of families of products
2. A high level of training, flexibility and empowerment of employees
3. Being self-contained, with its own equipment and resources
4. Test (poka-yoke) at each station in the cell
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Improving Layouts Using Work Cells
Current layout - workers in small closed areas.
Improved layout - cross-trained workers can assist each other. May be able to add a third worker as additional output is needed.
Figure 9.10 (a)
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Improving Layouts Using Work Cells
Current layout - straight lines make it hard to balance tasks because work may not be divided evenly
Improved layout - in U shape, workers have better access. Four cross-trained workers were reduced.
Figure 9.10 (b)
U-shaped line may reduce employee movement and space requirements while enhancing communication, reducing the number of workers, and facilitating inspection
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Staffing and Balancing Work Cells
Determine the takt timeDetermine the takt time
Takt time =Total work time available
Units required
Determine the number Determine the number of operators requiredof operators required
Workers required =Total operation time required
Takt time
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Staffing Work Cells Example
600 Mirrors per day requiredMirror production scheduled for 8 hours per dayFrom a work balance
chart total operation time = 140 seconds
Sta
nd
ard
tim
e re
qu
ired
Operations
Assemble Paint Test Label Pack forshipment
60
50
40
30
20
10
0
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Staffing Work Cells Example
600 Mirrors per day requiredMirror production scheduled for 8 hours per dayFrom a work balance
chart total operation time = 140 seconds
Takt time = (8 hrs x 60 mins) / 600 units = .8 mins = 48 seconds
Workers required =Total operation time required
Takt time
= 140 / 48 = 2.91
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Repetitive and Product-Oriented Layout
1. Volume is adequate for high equipment utilization
2. Product demand is stable enough to justify high investment in specialized equipment
3. Product is standardized or approaching a phase of life cycle that justifies investment
4. Supplies of raw materials and components are adequate and of uniform quality
Organized around products or families of similar high-volume, low-variety products
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Product-Oriented Layouts
Fabrication line
Builds components on a series of machines
Machine-paced
Require mechanical or engineering changes to balance
Assembly line
Puts fabricated parts together at a series of workstations
Paced by work tasks
Balanced by moving tasksBoth types of lines must be balanced so that the time to perform the work at each station is the same
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Product-Oriented Layouts
1. Low variable cost per unit
2. Low material handling costs
3. Reduced work-in-process inventories
4. Easier training and supervision
5. Rapid throughput
AdvantagesAdvantages
1. High volume is required
2. Work stoppage at any point ties up the whole operation
3. Lack of flexibility in product or production rates
DisadvantagesDisadvantages
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Disassembly Lines
Disassembly is being considered in new product designs
“Green” issues and recycling standards are important consideration
Automotive disassembly is the 16th largest industry in the US
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Assembly-Line Balancing
Objective is to minimize the imbalance between machines or personnel while meeting required output
Starts with the precedence relationships Determine cycle time
Calculate theoretical minimum number of workstations
Balance the line by assigning specific tasks to workstations
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Wing Component Example
This means that tasks B and E cannot be done until task A has been completed
Performance Task Must FollowTime Task Listed
Task (minutes) Below
A 10 —B 11 AC 5 BD 4 BE 12 AF 3 C, DG 7 FH 11 EI 3 G, H
Total time 66
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Wing Component Example
Performance Task Must FollowTime Task Listed
Task (minutes) Below
A 10 —B 11 AC 5 BD 4 BE 12 AF 3 C, DG 7 FH 11 EI 3 G, H
Total time 66 I
GF
C
D
H
B
E
A
10
1112
5
4 3
711 3
Figure 9.13
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I
GF
C
D
H
B
E
A
10
1112
5
4 3
711 3
Figure 9.13
Performance Task Must FollowTime Task Listed
Task (minutes) Below
A 10 —B 11 AC 5 BD 4 BE 12 AF 3 C, DG 7 FH 11 EI 3 G, H
Total time 66
Wing Component Example480 available
mins per day40 units required
Cycle time =
Production time available per day
Units required per day
= 480 / 40= 12 minutes per unit
Minimum number of
workstations=
∑ Time for task i
Cycle time
n
i = 1
= 66 / 12= 5.5 or 6 stations
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480 available mins per day
40 units required
Cycle time = 12 mins
Minimum workstations = 5.5 or 6
Performance Task Must FollowTime Task Listed
Task (minutes) Below
A 10 —B 11 AC 5 BD 4 BE 12 AF 3 C, DG 7 FH 11 EI 3 G, H
Total time 66Station 1
Wing Component Example
Station 2
Station 3Station 3
Station 4
Station 5
Station 6Station 6
I
GF
H
C
D
B
E
A
10 11
12
5
4
3 7
11
3
Figure 9.14
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Performance Task Must FollowTime Task Listed
Task (minutes) Below
A 10 —B 11 AC 5 BD 4 BE 12 AF 3 C, DG 7 FH 11 EI 3 G, H
Total time 66
Wing Component Example480 available
mins per day40 units required
Cycle time = 12 mins
Minimum workstations = 5.5 or 6
Efficiency =∑ Task times
(Actual number of workstations) x (Largest cycle time)
= 66 minutes / (6 stations) x (12 minutes)
= 91.7%
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Summary
The Strategic Importance of Layout Decisions
Types of Layout
Office Layout
Retail Layout
Warehousing and Storage Layouts
Fixed-Position Layout
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Summary – Continued
Process-Oriented Layout
Work Cells Requirements of Work Cells
Staffing and Balancing Work Cells
The Focused Work Center and the Focused Factory
Repetitive and Product-Oriented Layout Assembly-Line Balancing
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Chapter 12: Inventory ManagementChapter 12: Inventory Management
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Outline
Global Company Profile: Amazon.com
The Importance of Inventory Functions of Inventory
Types of Inventory
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Outline – Continued
Managing Inventory ABC Analysis
Record Accuracy
Cycle Counting
Control of Service Inventories
Inventory Models Independent vs. Dependent Demand
Holding, Ordering, and Setup Costs
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Outline – Continued
Inventory Models for Independent Demand The Basic Economic Order Quantity
(EOQ) Model
Minimizing Costs
Reorder Points
Production Order Quantity Model
Quantity Discount Models
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Outline – Continued
Probabilistic Models and Safety Stock Other Probabilistic Models
Single-Period Model
Fixed-Period (P) Systems
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Inventory Management
The objective of inventory management is to strike a balance between inventory
investment and customer service
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Importance of Inventory
One of the most expensive assets of many companies representing as much as 50% of total invested capital
Operations managers must balance inventory investment and customer service
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Functions of Inventory
1. To decouple or separate various parts of the production process
2. To decouple the firm from fluctuations in demand and provide a stock of goods that will provide a selection for customers
3. To take advantage of quantity discounts
4. To hedge against inflation
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Types of Inventory
Raw material Purchased but not processed
Work-in-process Undergone some change but not completed
Maintenance/repair/operating (MRO) Necessary to keep machinery and
processes productive
Finished goods Completed product awaiting shipment
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The Material Flow Cycle
Figure 12.1
Input Wait for Wait to Move Wait in queue Setup Run Outputinspection be moved time for operator time time
Cycle time
95% 5%
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Managing Inventory
1. How inventory items can be classified
2. How accurate inventory records can be maintained