Layout Strategies
Heizer, Render and Munson, 2017
The Objective of Layout Design
The objective of layout strategy is to develop an effective and efficient layout that will meet the firm’s competitive requirements.
Layout design must consider how to achieve:
•
Higher utilization of space, equipment, and people•
Improved flow of information, materials, and people•
Improved employee morale and safer working conditions•
Improved customer/client interaction•
Flexibility (whatever the layout is now, it will need to change)Types of Layout
1. Office layout: Positions workers, their equipment, and spaces/offices to provide for movement of information.
2. Retail layout: Allocates display space and responds to customer behavior.
3. Warehouse layout: Addresses trade-offs between space and material handling.
4. Fixed-position layout: Addresses the layout requirements of large, bulky projects such as ships and buildings.
5. Process-oriented layout: Deals with low-volume, high-variety production (also called “job shop,” or intermittent production).
6. Work-cell layout: Arranges machinery and equipment to focus on production of a single product or group of related products.
7. Product-oriented layout: Seeks the best personnel and machine utilization in repetitive or continuous production.
Good Layout Considerations
1. Material handling equipment
2. Capacity and space requirements 3. Environment and aesthetics
4. Flows of information
5. Cost of moving between various
work areas
Layout Strategies
Office Layout
•
Grouping of workers, theirequipment, and spaces to provide comfort, safety, and movement of information
•
Movement of information is main distinction•
Typically in constant flux due to frequent technological changesRelationship Chart
Five Versions of The Office Layout
Supermarket Retail Layout
▪
Objective is to maximize profitability per square foot of floor space▪
Sales and profitability vary directly with customer exposureFive Helpful Ideas for Supermarket Layout
1. Locate high-draw items around the periphery of the store 2. Use prominent locations for high-impulse and high-margin
items
3. Distribute power items to both sides of an aisle and disperse them to increase viewing of other items
4. Use end-aisle locations
5. Convey mission of store through careful positioning of
lead-off department
Servicescape considerations
1. Ambient conditions, which are background characteristics such as lighting, sound, smell, and temperature. All these affect workers and customers and can affect how much is spent and how long a person stays in the building.
2. Spatial layout and functionality, which involve customer
circulation path planning, aisle characteristics (such as width, direction, angle, and shelf spacing), and product grouping.
3. Signs, symbols, and artefacts, which are characteristics of building design that carry social significance (such as
carpeted areas of a department store that encourage
shoppers to slow down and browse).
Warehouse Layout
▪ The objective of warehouse layout is to find the optimum trade- off between handling cost and costs associated with warehouse space.
▪ Automated storage and retrieval systems (ASRSs)
▪ Cross-docking : avoiding placing materials or supplies in storage by processing them as they are received. It reduces product handling,
inventory, and facility costs, but requires both (1) tight scheduling and (2) accurate inbound product identification.
▪ Random stocking: locating stock wherever there is an open location.
▪ Customizing: Using warehousing to add value to a product through
component modification, repair, labelling, and packaging.
Fixed-Position Layout
Process-Oriented Layout
▪ Process-oriented layout groups machinery and equipment according to their functions.
▪ Facilitates production of a variety of nonstandard items in relatively small batches.
▪ Process layouts accommodate a variety of
production functions and use general-purpose
equipment that can be less costly to purchase and
maintain than specialized equipment.
Process-Oriented Layout Example (1) Patient Routes in An Emergency Room
Surgery
Radiology
ER triage
room
ER Beds Pharmacy
Emergency room admissions
Billing/exit Laboratories
Patient A - broken leg
Patient B - erratic heart pacemaker
Process-Oriented Layout Example (2) Arnold Palmer Hospital
Central break and medical supply rooms Local linen
supply
Local nursing pod
Pie-shaped rooms
Central nurses station
Process-Oriented Layout
◆ Arrange work centers so as to minimize the costs of material handling
◆ Basic cost elements are
◆ Number of loads (or people) moving between centers
◆ Distance loads (or people) move between centers
Process-Oriented Layout: The Model
Minimize cost = ∑ ∑
nX
ijC
iji = 1 n
j = 1
where n = total number of work centers or departments
i, j = individual departments
Xij = number of loads moved from department i to department j Cij = cost to move a load between
department i and department j
Process Layout Model Example
The process layout procedure involves six steps:
1. Construct a “from-to matrix”
2. Determine the space requirements 3. Develop an initial schematic diagram 4. Determine the cost of this layout
5. Try to improve the layout 6. Prepare a detailed plan
Arrange six departments in a factory to minimize
the material handling costs. Each department is 20
x 20 feet and the building is 60 feet long and 40 feet
wide.
Department Assembly Painting Machine Receiving Shipping Testing
(1) (2) Shop (3) (4) (5) (6)
Assembly (1) Painting (2) Machine Shop (3) Receiving (4) Shipping (5) Testing (6)
Number of loads per week
50 100 0 0 20
30 50 10 0
20 0 100
50 0
0
Process Layout Model Example
Area 1 Area 2 Area 3
Area 4 Area 5 Area 6
60’
40’
Process Layout Model Example
Receiving Shipping Testing
Department Department Department
(4) (5) (6)
Figure 9.5
Assembly Painting Machine Shop Department Department Department
(1) (2) (3)
Process Layout Model Example
Interdepartmental Flow Graph
100
50
50
10
100
30 Machine
Shop (3)
Testing (6) Shipping
(5) Receiving
(4) Assembly
(1)
Painting (2)
Process Layout Model Example
Cost = $50 + 2x$100 + 2x$20 (1 and 2) (1 and 3) (1 and 6)
+ $30 + $50 + $10
(2 and 3) (2 and 4) (2 and 5) + 2x$20 + $100 + $50
(3 and 4) (3 and 6) (4 and 5)
= $570
Cost = ∑ ∑
nX
ijC
iji = 1 n
j = 1
Process Layout Model Example
Revised Interdepartmental Flow Graph
30
50
50
50 100
100 Machine
Shop (3)
Testing (6) Shipping
(5) Receiving
(4) Painting
(2)
Assembly (1)
Process Layout Model Example
Cost = $50 + $100 + $20
(1 and 2) (1 and 3) (1 and 6)
+ 2x$30 + $50 + $10
(2 and 3) (2 and 4) (2 and 5) + 2x$20 + $100 + $50
(3 and 4) (3 and 6) (4 and 5)
= $480
Cost = ∑ ∑
nX
ijC
iji = 1 n
j = 1
Area 1 Area 2 Area 3
Area 4 Area 5 Area 6
60’
40’
Process Layout Model Example
Receiving Shipping Testing
Department Department Department
(4) (5) (6)
Painting Assembly Machine Shop Department Department Department
(2) (1) (3)
Work-Cell Layout
• An arrangement of machines and personnel that focuses on making a single product or family of related products.
• 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
Improving Layouts Using Work Cells
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
Staffing and Balancing Work Cells Procedure:
Determine the takt time
Takt time = Total work time available Units required
Determine the number of operators required
Workers required = Total operation time required Takt time
Takt time is the pace (frequency) of production
units necessary (time per unit) to meet customer orders
Staffing Work Cells Example
Stephen Hall’s company in
Dayton makes auto mirrors. The major customer is the Honda
plant nearby.
Honda expects 600 mirrors
delivered daily, and the work cell producing the mirrors is
scheduled for 8 hours
Standard time required (seconds)
Operations
Assemble Paint Test Label Pack for shipment 60
50 40 30 20 10 0
10
20
15 50
45
Staffing Work Cells Example
Takt time = (8 hrs x 60 mins) / 600 units
= .8 mins = 48 seconds
Workers required = Total operation time required Takt time
= 140 / 48 = 2.92 3 Total operation time required
= 50 + 45 + 10 + 20 + 15 = 140 seconds
With 3 operators this work cell will be producing each unit every
46.67 seconds (140 seconds/3 employees = 46.67)
Product Layout
▪ Product layout sets up production equipment along a product- flow line, and the work in process moves along this line past workstations.
▪ Efficiently produces large numbers of similar items.
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 tasks
Both types of lines must be balanced so that the
time to perform the work at each station is the same
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
Advantages
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
Disadvantages
McDonald’s Assembly Line
© 2011 Pearson Education, Inc.
publishing as Prentice Hall
Assembly-Line Balancing
◆ Objective is to minimize the imbalance between machines or personnel while meeting required output
◆ The line balancing procedure involves 4 steps
1. Starts with the precedence relationships 2. Determine cycle time
3. Calculate theoretical minimum number of workstations
4. Balance the line by assigning specific tasks to workstations
Line Balancing Example (Boeing-Wing Component)
This means that tasks B and E cannot be done until task A has been completed
Performance Task Must Follow Time Task Listed Task (minutes) Below
A 10 —
B 11 A
C 5 B
D 4 B
E 11 A
F 3 C, D
G 7 F
H 11 E
I 3 G, H
Total time 65
I F G
C
D
H B
E A
10
11 11
5
4 3
7
11 3
I F G
C
D
H B
E A
10
11 12
5
4 3
7
11 3
Performance Task Must Follow Time Task Listed Task (minutes) Below
A 10 —
B 11 A
C 5 B
D 4 B
E 11 A
F 3 C, D
G 7 F
H 11 E
I 3 G, H
Total time 65
480 available
mins per day 40 units required
Expected takt time =
Production time available per day Units required per day
= 480 / 40
= 12 minutes per unit
Minimum number of workstations =
∑ Time for task i Expected takt time
n i = 1
= 65 / 12
= 5.42 6 stations
Line Balancing Example
(Boeing-Wing Component)
480 available mins per day 40 units required
Expected takt time = 12 mins Minimum
workstations = 5.5 or 6 Performance Task Must Follow
Time Task Listed Task (minutes) Below
A 10 —
B 11 A
C 5 B
D 4 B
E 12 A
F 3 C, D
G 7 F
H 11 E
I 3 G, H
Total time 66
Station 1
Line Balancing Example (Boeing-Wing Component)
Station 2
Station 3 Station 3
Station
4 Station
5
Station 6 Station 6
I G
F
H C
D B
E A
10 11
11
5
4
3 7
11
3
Efficiency = ∑ Task times
(Actual number of workstations) x (Largest total proccessing time)
= 65 minutes / (6 stations) x (12 minutes)
= 90.3%
Idle time = (6 stations) x (12 minutes) – 65 minutes = 7 minutes
Ranked Positional Weight Technique Procedure
(Helgeson and Birnie (1961) in Biegel (1974, pp. 183-187))
:
1. Draw the precedence relationships for the production process
2. Assign a positional weight to each operation/task. The positional
weight is the sum of the times for all following operations/tasks plus the time of the operation/task itself.
3. Order the operations/tasks in the sequence of descending positional weights
4. Calculate the expected takt time
5. Assign the operations/tasks to workstations, based on the expected cycle time.
6. Find a better balanced solution, if possible.
Production process of a product requires 16 tasks described as follows
Line Balancing Using Ranked Positional Weight Technique Example
(Helgeson and Birnie (1961) in Biegel (1974))
S T A R T
1 3 4
5 7
9
2
6 8 10
11
12 13
14
15
F I N I S H 16
20 minutes
23 minutes
37 minutes 33 minutes 22 minutes 43 minutes
22 minutes
22 minutes 22 minutes 86 minutes
21 minutes 63
minutes 90 minutes
30 minutes
21 minutes
45 minutes
Step 2: Assign the positional weights
Operation Positional Weight (minutes) Operation Positional Weight (minutes)
1 255 9 173
2 235 10 214
3 237 11 192
4 304 12 128
5 277 13 106
6 247 14 170
7 186 15 84
8 165 16 63
Step 3: Descending order of positional weights
Operation Positional Weight (minutes) Operation Positional Weight (minutes)
4 304 7 186
5 277 9 173
1 255 14 170
6 247 8 165
3 237 12 128
2 235 13 106
10 214 15 84
11 192 16 63
Step 4: Calculate the cycle time
▪
Total time for one unit of product: (task time) = 600 minutes (10 man-hours)▪
1500 units needed annually (28 unit per week)▪
The longest processing time is 90 minutes for task 4, therefore if expected takt time is 90 minutes, the minimum number of workstations is:▪
However, if there are 7 workstations in the facility, and the workstations equally balanced, the expected cycle time should be 86 minutes (= 600/7) Minimum number of workstations = Total task time requiredExpected takt time = 600/90 = 6.67 7
Step 5: Assign the operations/task to workstations
S T A R T
1 3 4 5
7 9
2
6 8 10
11
12 13
14
15
F I N I S H 16
20 minutes
23 minutes
37 minutes 33 minutes 22 minutes 43 minutes
22 minutes
22 minutes 22 minutes 86 minutes
21 minutes 63 minutes 90 minutes
30 minutes
21 minutes
45 minutes
Descending order: 4-5-1-6-3-2-10-11-7-9-14-8-12-13-15-16
Step 5: Assign the operations/tasks to workstations
Workstation Operations/task Assigned Time (minutes) Workstation Efficiency (%)
1 4 90 100
2 5,1,6 30+20+33 = 83 92.22
3 3,2,10 23+43+22 = 88 97.78
4 11,7,9 22+21+45 = 88 97.78
5 14 86 95.56
6 8,12,13 37+22+22 = 81 90
7 15,16 21+63 = 84 93.33
Total 600 95.24
Step 6: Possible better-balanced solution
S T A R T
1 3 4 5
7 9
2
6 8 10
11
12 13
14
15
F I N
I S H 16
20 minutes
23 minutes
37 minutes 33 minutes 22 minutes 43 minutes
22 minutes
22 minutes 22 minutes 86 minutes
21 minutes 63 minutes 90 minutes
30 minutes
21 minutes
45 minutes
Step 6: Possible better-balanced solution
Workstation Operations/task Assigned Time (minutes) Workstation Efficiency (%)
1 4 90 100
2 5,6,7 30+33+21 = 84 93.33
3 1,2,3 20+43+23 = 86 95.56
4 8.9 37+45 = 82 91.11
5 10,11,12,13 22+22+22+22=88 97.78
6 14 86 95.56
7 15,16 21+63 = 84 93.33
Total 600 95.24
