Layout and flow
Source: Alamy/AG Stock USA Inc.
Layout and flow
Functional design
Operations
strategy
Supply network design
Layout
and flow
Functional
technology
Design
Job
design
Product/service
design
Operations
management
Improvement
Planning and
control
1
Layout involves the relative positioning of transformed
resources within operations and functions and the allocation
of tasks to the resources, which together dictate the flow of
transformed resources through the operation or function
Relative positioning of
transforming resources
Allocation of tasks to
transforming resources
Flow of transformed
resources
Source: J Sainsbury plc
2
Detailed design techniques
Fixed position – resource location analysis
Functional layout – flow charts and relationship charts
Cell layout – product flow analysis
Product layout – assembly line balancing techniques
Example of a functional layout in a library,
showing the path of just one customer
Loan books in subject order
Online and
CD-ROM
access room
Study desks
Enquiries
Company reports
To
journal
stack
Current
journals
Reference
section
Reserve
collection
Store
room
Entrance
Counter staff
Copying area
Exit
3
Ground-floor plan of a department store, showing the
sports goods shop-within-a-shop retail ‘cell’
Books
and
videos
Footwear
Sports shop
Menswear
Entrance
Perfumes
& jewellery
Confectionery,
newspapers,
magazines,
stationery
Elevators
Women’s clothing
Luggage
and gifts
Entrance
An army induction centre which uses product layout
Waiting
area
Lecture theatre
Doctor
Waiting
area
Doctor
Blood
test
X-ray
Uniform
issuing area
Doctor
Doctor
Blood
test
Records:
personal
history and
medical
details
X-ray
Uniform
store
Doctor
Doctor
Blood
test
X-ray
4
A product layout in a paper manufacturing operation
A restaurant complex with all four basic layout types
Cell layout buffet
Line
layout
cafeteria
Starter
buffet
Dessert
buffet
Fixed-position layout
service restaurant
Main course
buffet
Service line
Oven
Preparation
Functional layout kitchen
Cool room
Freezer
Vegetable preparation
Grill
5
Advantages and disadvantages
Fixed-position layout
Very high product and mix
flexibility
Advantages
Product/customer not moved
High variety of tasks for staff
Very high unit costs
Disadvantages
Scheduling space and activities
can be difficult
Advantages and disadvantages
Functional layout
High product and mix flexibility
Advantages
Relatively robust in the case of
disruptions
Easy to supervise
Low utilization
Disadvantages
Can have very high WIP
Complex flow
6
Advantages and disadvantages
Cell layout
Can give good compromise
Advantages
Fast throughput
Group work can result in good
motivation
Disadvantages
Can be costly to rearrange
existing layout
Can need more plant
Advantages and disadvantages
Product layout
Low unit costs for high volume
Advantages
Opportunities for specialization
of equipment
Can have low mix flexibility
Disadvantages Not very robust in the case of
disruptions
Work can be very repetitive
7
Low
High
Volume
Fixed-position
layout
Variety
Functional
layout
Cell layout
Low
Product
layout
Regular flow more important
Regular flow more feasible
High
Flow is
intermittent
Flow
becomes
continuous
Relationship between functional types and basic layout types
Manufacturing
functional types
Project processes
Basic layout
types
Service
functional types
Fixed-position layout
Professional services
Jobbing processes
Functional layout
Service shops
Batch processes
Cell layout
Mass services
Mass processes
Product layout
Continuous processes
8
Costs
The basic layout types have different fixed and variable cost
characteristics that seem to determine which one to use
Use
cell
Use
Use fixed- functional
position
Use product
Volume
Costs
In practice, uncertainty about the exact fixed and variable costs of
each layout means the decision can rarely be made on cost alone
Fixed-position
Functional
Cell
Product
?
?
?
?
Use product
Use fixed-position
Use fixed-position or functional
Use functional
Volume
Use cell or product
Use functional or cell or product
Use functional or cell
9
Collecting information in functional layout
(a)
(b)
Loads per day
To
From
A
A
B
B
C
D
17
-
30 10
A
20
B
13
C
Loads per day
20
-
10
-
-
D
30
E
10 10 10 10
E
70
30
A
If direction is
not important,
collapses to
B
C
D
30
-
60 20
30
C
E
-
30
80
D
40
E
Collecting information in functional layout
(b)
Loads per day
A
A
B
C
D
B
30
C
30
D
E
(c)
60 20
-
Loads per day
A
B
30
C
80
40
Or alternatively
D
E
30
30
40
80
60
30
20
E
10
Collecting information in functional layout
(a)
(d)
Unit cost per distance
travelled
Loads per day
To
From
A
A
B
B
C
D
E
2
2
2
2
3
3
4
2
2
D
17
-
30 10
A
20
B
3
C
2
D
10 10 10
E
2
20
-
10
-
-
D
30
E
10 10 10 10
E
A
C
13
C
To
B
70
30
From
If cost of flow
differs between
work centres,
combine with
2
2
2
10
2
Collecting information in functional layout
(d)
(e)
Unit cost per distance
travelled
To
From
A
A
Daily cost per distance
travelled
To
B
C
D
E
2
2
2
2
A
3
3
4
B
2
2
B
3
C
2
D
10 10 10
E
2
2
2
2
10
2
From
To give
A
C
34
39
C
D 300
E
B
D
E
60 20
60
60
20
140
-
300
20 20 20 20
11
Collecting information in functional layout
(e)
(f)
Daily cost per distance
travelled
To
From
A
B
A
B
34
39
D
A
A
60
B
20
D 300
E
60 20
60
C
E
C
Daily cost per distance
travelled
140 If direction is not
-
important,
collapses to
300
20 20 20 20
C
D
B
C
73
-
D
E
360 40
80
80
-
160
320
E
A relationship chart
CODE
A
E
I
O
U
X
DEPARTMENT
Metrology
E
Electronic testing
CLOSENESS
Absolutely necessary
Especially important
Important
Ordinary closeness
Unimportant
Undesirable
A
I
Analysis
O
X
U
I
Ultrasonic testing
U
O
I
Fatigue testing
X
U
U
O
E
Impact testing
12
Types of cell
Amount of indirect resources included in the cell
High
e.g. Plant-within-a-plant
manufacturing
operation
e.g. Specialist functional
manufacturing cell
Internal audit group
in a bank
Maternity unit
in a hospital
Low
e.g. Complete
component
manufacturing cell
e.g. Small multi-machine
manufacturing cell
Joint reference and
copying room in a
library
Proportion of
the resources
needed to
complete the
High transformation
included in the
cell
Lunch and snack
produce area in
supermarket
Low
Using production flow analysis to allocate
machines to cells
1
Component families
2 3 4 5 6 7
1
X
Machines
2 X
3
X
X
5 X
X
8
X
4 X
X
X
1
X
X
X
X
X
7
X
X
X
6
3
X
X
X
X
Component families
6 8 5 2 4 1
8
X
X
X
4
(b)
X
Machines
(a)
6 X
X
3
X
X
X
8
X
X
X
8
2
X
X
X
5
X
X
X
7
X
X
13
Balancing loss is that proportion of the time invested in
processing the product or service which is not used productively
An ideal ‘balance’ where work is allocated equally
between the stages
3
Work allocated to stage
Cycle time = 2.5 mins
2.5
Load
2
1.5
1
0.5
0
1
2
Stage
3
4
Balancing loss is that proportion of the time invested in
processing the product or service which is not used productively
3.5
But if work is not equally allocated, the cycle time will increase and
‘balancing losses’ will occur
Cycle time = 3.0 mins
3
Work allocated to stage
Idle time
2.5
Calculating balancing loss:
Load
2
Idle time
= (3.0 – 2.3) + (3.0 – 2.5) + (3.0 – 2.2)
every cycle
= 2.0 mins
1.5
Balancing
loss
1
2.0
4 × 3.0
= 0.1667
= 16.67%
0.5
0
=
1
2
Stage
3
4
14
Element listing for Karlstad Cakes
Element
a
De-tin and trim
0.12 mins
Element
b
Reshape with offcuts
0.30 mins
Element
c
Clad in almond fondant
0.36 mins
Element
d
Clad in white fondant
0.25 mins
Element
e
Decorate, red icing
0.17 mins
Element
f
Decorate, green icing
0.05 mins
Element
g
Decorate, blue icing
0.10 mins
Element
h
Affix transfers
0.08 mins
Element
i
Transfer to base and pack
0.25 mins
Total work content = 1.68 mins
Precedence diagram for Karlstad Cakes
0.17 mins
e
0.30 mins
a
0.12 mins
b
0.25 mins
c
0.36 mins
d
0.25 mins
0.05 mins
f
g
i
0.10 mins
h
0.08 mins
15
Allocation of elements to stages and balancing loss
for Karlstad Cakes
Stage 1
Stage 2
0.30 mins
a
0.12 mins
b
Stage 3
0.25 mins
c
0.36 mins
0.17 mins
e
Stage 4
0.05 mins
f
d
0.25 mins
i
g
0.10 mins
h
0.08 mins
0.6
0.5
Cycle time = 0.48 mins
Idle time
every cycle
0.4
= (0.48 – 0.42) + (0.48 – 0.36) + (0.48 – 0.42)
0.3
= 0.24 mins
0.2
Proportion of
0.24
idle time per = 4 × 0.48
cycle
= 12.5%
0.1
0
1
2
3
4
Long and thin versus short and fat layouts
A 60-minute task with a required cycle time of 15 minutes
cess
in pro
h
t
g
Lon
15
15
15
1 every 15
minutes
15
60
30
30
30
30
1 every 15
minutes
60
1 every 15
minutes
60
60
Sho
ss
roce
p
t
rt fa
16
Long and thin versus short and fat
Long or short describes the number of stages
Fat or thin describes the amount of work at each stage
Advantages of long-thin processes
Advantages of short-fat processes
controlled flow
simple materials handling
lower capital requirement
(no duplication)
greater efficiency
higher space utilization
higher mix flexibility
higher volume flexibility
greater robustness
less monotonous
higher ownership
Calculating the required cycle time
Forecast demands during the period (A)
100
Availability of productive time (B)
480 mins
Cycle time (C = B/A)
4.8 mins
Deciding how many staff are needed
Work content of the task (D)
55 mins
Cycle time required (C)
4.8 mins
Number of staff (D/C)
11.46 (12)
17
Key Terms Test
Fixed-position layout
Locating the position of a product or service such that it remains
largely stationary, while transforming resources are moved to
and from it.
Cell layout
Locating transforming resources with a common purpose such
as processing the same types of product, serving similar
types of customer, etc., together in close proximity (a cell).
Product layout
Locating transforming resources in a sequence defined by the
processing needs of a product or service.
Key Terms Test
Shop-within-a-shop
An operations layout which groups together facilities that have a
common purpose; the term was originally used in retail operations
but is now sometimes used in other industries, very similar to the
idea of a cell layout.
Line layout
A more descriptive term for what is technically a product layout.
Combinatorial complexity
The idea that many different ways of processing products and services
at many different locations or points in time combine to result in an
exceptionally large number of feasible options; the term is often
used in facilities layout and scheduling to justify non-optimal
solutions (because there are too many options to explore).
18
Key Terms Test
Flow record chart
A diagram used in layout to record the flow of products or
services between facilities.
Relationship chart
A diagram used in layout to summarize the relative
desirability of facilities to be close to each other.
Heuristic procedures
‘Rules of thumb’ or simple reasoning short-cuts that are
developed to provide good but non-optimal solutions,
usually to operations decisions that involve combinatorial
complexity.
Key Terms Test
CRAFT
Computerized Relative Allocation of Facilities Technique, a
heuristic technique for developing good, but non-optimal,
solutions.
Cluster analysis
A technique used in the design of cell layouts to find which
process groups fit naturally together.
Production flow analysis (PFA)
A technique that examines product requirements and
process grouping simultaneously to allocate tasks and
machines to cells in cell layout.
19
Key Terms Test
Remainder cell
The cell that has to cope with all the products that do
not conveniently fit into other cells.
Cycle time
The average time between units of output emerging
from a process.
Total work content
The total amount of work required to produce a unit of
output, usually measured in standard times.
Key Terms Test
Line balancing
The activity of attempting to equalize the load on each
station or part of a line layout or mass process.
Balancing loss
The quantification of the lack of balance in a production
line, defined as the time that is not used for
productive purposes expressed as a percentage of
the total time invested in making a product.
20
Key Terms Test
Long thin
A process designed to have many sequential stages,
each performing a relatively small part of the total
task; the opposite of a short fat process.
Short fat
A process designed to have relatively few sequential
stages, each of which performs a relatively large part
of the total task; the opposite of a long thin process.
21