Process layout

Process layout
decease waste and cut cos

1. © 2007 Pearson Education
D D
D D
G G
G G
G G
M M
M M
M M
A A
A A
L
L L
L L
L L
L
Process Layout
Chapter 8Chapter 8

2. © 2007 Pearson Education
Layout Planning
Layout planning is planning that involves decisions
about the physical arrangement of economic activity
centers needed by a facility’s various processes.
Layout plans translate the broader decisions about the
competitive priorities, process strategy, quality, and capacity
of its processes into actual physical arrangements.
Economic activity center: Anything that consumes
space -- a person or a group of people, a customer
reception area, a teller window, a machine, a
workstation, a department, an aisle, or a storage
room.

3. © 2007 Pearson Education
Before a manager can make decisions
regarding physical arrangement, four
questions must be addressed.
1.What centers should the layout include?
2.How much space and capacity does
each center need?
3.How should each center’s space be
configured?
4.Where should each center be located?
Layout Planning
Questions

4. © 2007 Pearson Education
Facility Layout
Defined
Facility layout can be defined as the process by which the
placement of departments, workgroups within
departments, workstations, machines, and stock-
holding points within a facility are determined
This process requires the following inputs:
Specification of objectives of the system in terms of output
and flexibility
Estimation of product or service demand on the system
Processing requirements in terms of number of operations
and amount of flow between departments and work
centers
Space requirements for the elements in the layout
Space availability within the facility itself
7A-4

5. © 2007 Pearson Education
Process Layout: Interdepartmental Flow
Given
The flow (number of moves) to and from all
departments
The cost of moving from one department to
another
The existing or planned physical layout of
the plant
Determine
The “best” locations for each department,
where best means maximizing flow, which
minimizing costs
7A-5

6. © 2007 Pearson Education
Process Layout: Systematic Layout Planning
Numerical flow of items between workcenters
Can be impractical to obtain
Does not account for the qualitative factors that
may be crucial to the placement decision
Systematic Layout Planning
Accounts for the importance of having each
department located next to every other
department
Is also guided by trial and error
Switching workcenters then checking the results of
the “closeness” score
7A-6

7. © 2007 Pearson Education
Strategic Issues
Layout choices can help communicate an
organization’s product plans and competitive
priorities.
Altering a layout can affect an organization and how
well it meets its competitive priorities in the following
ways:
1.Increasing customer satisfaction and sales at a retail store.
2.Facilitating the flow of materials and information.
3.Increasing the efficient utilization of labor and equipment.
4.Reducing hazards to workers.
5.Improving employee morale.
6.Improving communication.

8. © 2007 Pearson Education
Performance Criteria
Customer satisfaction
Level of capital investment
Requirements for materials handling
Ease of stockpicking
Work environment and “atmosphere”
Ease of equipment maintenance
Employee and internal customer attitudes
Amount of flexibility needed
Customer convenience and levels of sales

9. © 2007 Pearson Education
Types of Layouts
Flexible-flow layout: A layout that organizes
resources (employees) and equipment by function
rather than by service or product.
Line-flow layout: A layout in which workstations or
departments are arranged in a linear path.
Hybrid layout: An arrangement in which some
portions of the facility have a flexible-flow and
others have a line-flow layout.
Fixed-position layout: An arrangement in which
service or manufacturing site is fixed in place;
employees along with their equipment, come to the
site to do their work.

10. © 2007 Pearson Education
A Flexible (process
oriented) Flow Layout
Foundry
Milling
machines
LathesGrinding
Painting Drills
Office
Welding
Forging
A job shop has a flexible-flow layout.

11. © 2007 Pearson Education
Process-Oriented LayoutProcess-Oriented Layout
Like machines and equipment are Like machines and equipment are
grouped togethergrouped together
Flexible and capable of handling a Flexible and capable of handling a
wide variety of products or serviceswide variety of products or services
Scheduling can be difficult and Scheduling can be difficult and
setup, material handling, and labor setup, material handling, and labor
costs can be highcosts can be high

12. © 2007 Pearson Education
Process-Oriented LayoutProcess-Oriented Layout
Arrange work centers so as to Arrange work centers so as to
minimize the costs of material minimize the costs of material
handlinghandling
Basic cost elements areBasic cost elements are
Number of loads (or people) moving Number of loads (or people) moving
between centersbetween centers
Distance loads (or people) move Distance loads (or people) move
between centersbetween centers

13. © 2007 Pearson Education
Office LayoutOffice Layout
Grouping of workers, their equipment, Grouping of workers, their equipment,
and spaces to provide comfort, safety, and spaces to provide comfort, safety,
and movement of informationand movement of information
Movement of Movement of
information is main information is main
distinctiondistinction
Typically in state of Typically in state of
flux due to frequent flux due to frequent
technological technological
changeschanges

14. © 2007 Pearson Education
Example of Systematic Layout Planning:
Importance of Closeness
Value
A
E
I
O
U
X
Closeness
Line
code
Numerical
weights
Absolutely necessary
Especially important
Important
Ordinary closeness OK
Unimportant
Undesirable
16
8
4
2
0
80
7A-14

15. © 2007 Pearson Education
Relationship ChartRelationship Chart
Figure 9.1Figure 9.1

16. © 2007 Pearson Education
Fixed-Position LayoutFixed-Position Layout
Product remains in one place Product remains in one place
Workers and equipment come to siteWorkers and equipment come to site
Complicating factorsComplicating factors
Limited space at siteLimited space at site
Different materials Different materials
required at different required at different
stages of the projectstages of the project
Volume of materials Volume of materials
needed is dynamicneeded is dynamic

17. © 2007 Pearson Education
Line Flow (product
oriented) Layout
Station 1 Station 2 Station 3 Station 4
A production line has a line-flow layout.

18. © 2007 Pearson Education
McDonald’s Assembly McDonald’s Assembly
LineLine
Figure 9.12Figure 9.12

19. © 2007 Pearson Education
Product-Oriented LayoutProduct-Oriented Layout
1.1.Volume is adequate for high equipment utilizationVolume is adequate for high equipment utilization
2.2.Product demand is stable enough to justify high Product demand is stable enough to justify high
investment in specialized equipmentinvestment in specialized equipment
3.3.Product is standardized or approaching a phase of Product is standardized or approaching a phase of
life cycle that justifies investment life cycle that justifies investment
4.4.Supplies of raw materials and components are Supplies of raw materials and components are
adequate and of uniform qualityadequate and of uniform quality
Organized around products or families of similar Organized around products or families of similar
high-volume, low-variety productshigh-volume, low-variety products

20. © 2007 Pearson Education
Product-Oriented LayoutsProduct-Oriented Layouts
1.1.Low variable cost per unitLow variable cost per unit
2.2.Low material handling costsLow material handling costs
3.3.Reduced work-in-process inventoriesReduced work-in-process inventories
4.4.Easier training and supervisionEasier training and supervision
5.5.Rapid throughputRapid throughput
AdvantagesAdvantages
1.1.High volume is requiredHigh volume is required
2.2.Work stoppage at any point ties up the whole Work stoppage at any point ties up the whole
operationoperation
3.3.Lack of flexibility in product or production ratesLack of flexibility in product or production rates
DisadvantagesDisadvantages

21. © 2007 Pearson Education
Comparison of Product vs.
Product Layouts
Process Layouts Product Layouts
Products: large #, different small # efficiently
Resources: general purpose specialized
Facilities: more labor intensive more capital intensive
Flexibility: greater relative to market lower relative to market
Processing slower faster
Rates:
Handling costs: high low
Space requirements: higher lower

22. © 2007 Pearson Education
Assembly Line
Balancing
Line balancing is the assignment of work to
stations in a line so as to achieve the desired output
rate with the smallest number of workstations.
Work elements are the smallest units of work that
can be performed independently.
Immediate predecessors are work elements that
must be done before the next element can begin.
Precedence diagram allows one to visualize
immediate predecessors better; work elements are
denoted by circles, with the time required to perform
the work shown below each circle.

23. © 2007 Pearson Education
Assembly Line
Balancing
Step 1: Identify tasks & immediate predecessors
Step 2: Determine the desired output rate
Step 3: Calculate the cycle time
Step 4: Compute the theoretical minimum
number
of workstations
Step 5: Assign tasks to workstations (balance the
line)
Step 6: Compute efficiency, idle time & balance
delay

24. © 2007 Pearson Education
Assembly Line
Balancing
1.Precedence diagram: circles=tasks, arrows show
the required sequence.
2.Determine cycle time:
3.Determine required workstations (theoretical
minimum)
4.Set rules for assigning tasks (number of following
tasks, longest task time)
unitput)/time_demand(out
/time_unitproduction
D
P
C==
cycle_time
task_times
C
T
N
å
==
t

25. © 2007 Pearson Education
Assembly Line
Balancing
5.Assign tasks to first workstation, using rules and
staying within cycle time. Repeat for following
workstations until all tasks are assigned.
6.Evaluate line efficiency:
7.Rebalance if efficiency is not satisfactory.
kstationsactual_worN;
CN
T
E -=
a
a

26. © 2007 Pearson Education
Step 1: Identify Tasks
& Immediate
Predecessors
Example 10.4 Vicki's Pizzeria and the Precedence Diagram
Immediate Task Time
Work ElementTask Description Predecessor (seconds
A Roll dough None 50
B Place on cardboard backing A 5
C Sprinkle cheese B 25
D Spread Sauce C 15
E Add pepperoni D 12
F Add sausage D 10
G Add mushrooms D 15
H Shrinkwrap pizza E,F,G 18
I Pack in box H 15
Total task time 165

27. © 2007 Pearson Education
Layout Calculations
Step 2: Determine output rate
Vicki needs to produce 60 pizzas per hour
Step 3: Determine cycle time
The amount of time each workstation is allowed to
complete its tasks
Limited by the bottleneck task (the longest task in a
process):
( )
( )
sec./unit 60
units/hr 60
sec/min 60x min/hr 60
units/hroutput desired
sec./day time available
)(sec./unit time Cycle ===
hourper pizzasor units/hr, 72
sec./unit 50
sec./hr. 3600
time task bottleneck
time available
output Maximum ===

28. © 2007 Pearson Education
Layout Calculations (continued)
Step 4: Compute the theoretical minimum
number of stations
TM = number of stations needed to achieve 100%
efficiency (every second is used)
Always round up (no partial workstations)
Serves as a lower bound for our analysis
( )
stations 3or 2.75,
nsec/statio 60
seconds 165
time cycle
times task
TM ===
å

29. © 2007 Pearson Education
Layout Calculations (continued)
Step 5: Assign tasks to workstations
Start at the first station & choose the longest eligible task following
precedence relationships
Continue adding the longest eligible task that fits without going over the
desired cycle time
When no additional tasks can be added within the desired cycle time, begin
assigning tasks to the next workstation until finished
WorkstationEligible taskTask SelectedTask timeIdle time
A A 50 10
B B 5 5
C C 25 35
D D 15 20
E, F, G G 15 5
E, F E 12 48
F F 10 38
H H 18 20
I I 15 5
1
2
3

30. © 2007 Pearson Education
Last Layout Calculation
Step 6: Compute efficiency and balance delay
Efficiency (%) is the ratio of total productive time
divided by total time
Balance delay (%) is the amount by which the line
falls short of 100%
( )91.7%100
sec. 60x stations 3
sec. 165
NC
t
(%) Efficiency ===
å
8.3%91.7%100%delay Balance =-=

31. © 2007 Pearson Education
Line Balancing
Example 8.3Example 8.3
Green Grass, Inc., a manufacturer of lawn & garden equipment,
is designing an assembly line to produce a new fertilizer spreader,
the Big Broadcaster..

32. © 2007 Pearson Education
Using the information in the previous slide,
answer the following questions:
1.Construct a Precedence diagram
2.If the company would like to product 60 units
per hour determine cycle time:
5.Determine required workstations (theoretical
minimum)
6.Assign tasks to workstations
7.Calculate line efficiency:

33. © 2007 Pearson Education© 2007 Pearson Education
Line Balancing
Green Grass, Inc.Green Grass, Inc.
66
E
2020
H
1818
I
4040
D
3030
B
2525
F
5050
C
4040
A
1515
G
AA Bolt leg frame to hopperBolt leg frame to hopper4040 NoneNone
BB Insert impeller shaftInsert impeller shaft 30 30 AA
CC Attach axleAttach axle 5050 AA
DD Attach agitatorAttach agitator 4040 BB
EE Attach drive wheelAttach drive wheel 66 BB
FF Attach free wheelAttach free wheel 2525 CC
GG Mount lower postMount lower post 1515 CC
HH Attach controlsAttach controls 2020 D, ED, E
II Mount nameplateMount nameplate 1818 F, GF, G
TotalTotal 244244
WorkWork Time Time Immediate Immediate
ElementElement DescriptionDescription (sec) (sec) Predecessor(s) Predecessor(s)

34. © 2007 Pearson Education
Application 8.3

35. © 2007 Pearson Education
Using the information in the previous slide, answer the
following questions:
1.Construct a Precedence diagram
2.If the company would like to product 60 units per
hour determine cycle time:
5.Determine required workstations (theoretical
minimum)
6.Assign tasks to workstations
7.Calculate line efficiency:

36. © 2007 Pearson Education
Solved Problem 2

37. © 2007 Pearson Education
Solved Problem 2
Precedence Diagram
2020
E
145145
H
130130
I
2525
D
8080
B
1515
F
5050
C
4040
A
120120
G
115115
J

38. © 2007 Pearson Education
Solved Problem 2
Line Balancing Process

39. © 2007 Pearson Education
Solved Problem 2
Line Balancing Solution
2020
E
145145
H
130130
I
2525
D
8080
B
1515
F
5050
C
4040
A
120120
G
115115
JS1
S4
S2
S5
S3