Process Design and Facility Layout
Process Design and Facility Layout
Process Design and Facility Layout
Process Design
and
Facility Layout
1
Introduction
• Make or Buy?
– Available capacity, excess capacity
– Expertise, knowledge, know-how exists?
– Quality Consideration, specialized firms, control
over quality if in-house
– The nature of demand, aggregation
– Cost
Make some components buy remaining
2
Introduction
www.utdallas.edu/~metin/Ba3352/Slides/layout
.
• Process selection
– Deciding on the way production of
goods or services will be organized
• Major implications
– Capacity planning
– Layout of facilities
– Equipment, Capital-equipment or
labor intensive
– Design of work systems
• New product and service,
technological changes, and
competitive pressures 3
Process Selection and System Design
Facilities and
Forecasting Capacity Equipment
Planning
Process
Technological Selection Work
Change Design
Figure 6.1
4
Process Types
• Variety of products
and services
– How much
• Flexibility of the process; volume,
mix, technology and design
– What type and degree Batch
• Volume
– Expected output
Job Shop Continuous
Repetitive
6
Product – Process Matrix
7
Variety, Flexibility, & Volume
Product
Product High Moderate Low Very
High Moderate Low VeryLow
Low
Variety
Variety
Equipment
Equipment High Moderate Low Very
High Moderate Low VeryLow
Low
flexibility
flexibility
Low
Low Job
Shop
Volume
Volume
Moderate
Moderate Batch
Volume
Volume
High
High Repetitive
assembly
Volume
Volume
Very
Veryhigh
high Continuous
Flow
Volume
Volume
8
Product – Process Matrix
9
Product-Process Matrix
Few High
Low Multiple Major Volume,
Volume Products, Products, High
One of a Low Higher Standard-
Kind Volume Volume ization
Flexibility-
Job Book
Quality
Shop Writing
Batch Movie
Theaters
Assembly Automobile
Line Assembly
Continuous Sugar
Flow Refinery Dependability-
Cost
Flexibility-Quality Dependability-Cost
10
Automation: Machinery that has sensing and control
devices that enables it to operate
Show wafer_handler_web
12
Flexible Manufacturing System
• Group of machines that include supervisory computer
control, automatic material handling, robots and other
processing equipment
– Advantage:
reduce labor costs and more consistent quality
lower capital investment and higher flexibility than
hard automation
relative quick changeover time
– Disadvantage
used for a family of products and require longer
planning and development times
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Computer-integrated manufacturing
• Use integrating computer system to link a broad
range of manufacturing activities, including
engineering design, purchasing, order processing
and production planning and control
• Advantage:
rapid response to customer order and product
change, reduce direct labor cost, high quality
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Service Blueprint
Yes
A View on Lecture
No
Begin
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Service Process Design
• Establish boundaries
• Identify steps involved
• Prepare a flowchart
• Identify potential failure points
• Establish a time frame for operations
• Analyze profitability
16
Layout
17
The Need for Layout Decisions
Inefficient operations
For Example: Changes in the design
High Cost of products or services
Bottlenecks
Accidents
The introduction of new
products or services
Safety hazards
18
The Need for Layout Design (Cont’d)
Changes in
environmental Changes in volume of
or other legal output or mix of
requirements products
Morale problems
Changes in methods
and equipment
19
Basic Layout Types
• Product Layout
– Layout that uses standardized processing operations
to achieve smooth, rapid, high-volume flow
• Auto plants, cafeterias
• Process Layout
– Layout that can handle varied processing requirements
• Tool and die shops, university departments
• Fixed Position Layout
– Layout in which the product or project remains
stationary, and workers, materials, and equipment are
moved as needed
• Building projects, disabled patients at hospitals
• Combination Layouts
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A Flow Line for Production or Service
21
A U-Shaped Production Line
Process Layout
(functional)
Dept. A Dept. C Dept. E
23
Process Layout
Milling
Assembly
Grinding
& Test
Drilling Plating
Process Layout - work travels
to dedicated process centers
24
Layout types: Product or Process Make your pick
25
Process vs Layout types
• Job Shop • Product
• Repetitive • Fixed-point
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Product layout
Advantages Disadvantages
– High volume – Lacks flexibility
– Low unit cost • Volume, design, mix
– Low labor skill needed – Boring for labor
– Low material handling • Low motivation
– High efficiency and • Low worker enrichment
utilization – Can not accommodate
– Simple routing and partial shut
scheduling downs/breakdowns
– Simple to track and
– Individual incentive
control
plans are not possible
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Cellular Layouts
• Cellular Manufacturing
– Layout in which machines are grouped into a cell that
can process items that have similar processing
requirements. A product layout is visible inside each
cell.
• Group Technology
– The grouping into part families of items with similar
design or manufacturing characteristics. Each cell is
assigned a family for production. This limits the
production variability inside cells, hence allowing for a
product layout.
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A Group of Parts
30
Process Layout
22
444 3333
222
444
44
111 333
33
44
333
33
4
111
3
333
111
Heat 111 Gear
333 Lathes
treat cutting 444
31
Cellular Manufacturing Layout
Heat Gear
-1111 Lathe Mill Drill -1111
treat cut
Heat
Mill Drill Grind - 2222
Assembly
222222222 treat
Heat
3333333333 Lathe Mill Grind - 3333
treat
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Basic Layout Formats
Part Family Y
Final Product
33
Fixed-Position and combination Layout
• Fixed-Position Layout:
item being worked on remains stationary,
and workers, materials and equipment are
moved as needed.
Example: buildings, dams, power plants
• Combination Layouts:
combination of three pure types.
Example: hospital: process and fixed position.
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Service Layouts
35
Design Product Layouts: Line Balancing
Worker 1 Worker 2
Bottleneck
60/hr. 60/hr.
1 min. 1 min. 1 min.
30/hr.
2 min. 30/hr.
Parallel Workstations
37
The obstacle
• The difficulty to forming task bundles that have the
same duration.
• The difference among the elemental task lengths
can not be overcome by grouping task.
– Ex: Can you split the tasks with task times {1,2,3,4} into
two groups such that total task time in each group is the
same?
– Ex: Try the above question with {1,2,2,4}
• A required technological sequence prohibit the
desirable task combinations
– Ex: Let the task times be {1,2,3,4} but suppose that the
task with time 1 can only done after the task with time 4 is
completed. Moreover task with time 3 can only done
after the task with time 2 is completed. How to group?
38
Cycle Time
Example: If a student can answer a multiple choice question in 2 minutes but gets a test with
30 questions and is given only 30 minutes then
OT=30 minutes; D=30
Desired cycle time=1 minute < 2 minutes = Cycle time from the process capability
40
Determine the Minimum Number
of Workstations Required: Efficiency
Example: Students can answer a multiple choice question in 2 minutes but given a test with
30 questions and is given only 30 minutes. What is the minimum number of students to
collaborate to answer all the questions in the exam?
Total operation (task) time = 60 minutes = 30 x 2 minutes
Operating time=30 minutes
60/3=2 students must collaborate. This Nmin below.
N min
t
Total task time for a product t
OT/D Availabale time for a product CT
I
dle
timeperc
yc
le
P
er
cen
tid
le
tim
e=
(
N)(
CT)
42
Example 1: Precedence Diagram
a b
c d e
0.7 min. 0.5 min. 0.2 min.
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Example 1: Assembly Line Balancing
Work-
Work- Time
Time Assign
Assign Station
Station
Station
Station Remaining
Remaining Eligible
Eligible Task
Task Idle
IdleTime
Time
11 1.0
1.0 a,c
a,c aa
.9
.9 cc cc
.2
.2 none
none -- .2
.2
22 1.0
1.0 bb bb
00 none
none -- 00
33 1.0
1.0 dd dd
.5
.5 ee ee
.3
.3 -- -- .3
.3
.5
.5
- Eligible operation fits into the remaining time and its predecessors are already assigned.
- What is the minimum cycle time possible for this example?
45
Calculate Percent Idle Time
0.2 0 0.3
Percent idle time = 0.167 16.7%
(3)(1)
46
Line Balancing Heuristic Rules
Work-
Work- Time
Time Assign
Assign Station
Station
Station
Station Remaining
Remaining Eligible
Eligible Task
Task Idle
IdleTime
Time
11 1.0
1.0 a,c
a,c cc
.9
.9 aa aa
.2
.2 none
none -- .2
.2
22 1.0
1.0 bb bb
00 none
none -- 00
33 1.0
1.0 dd dd
.5
.5 ee ee
.3
.3 -- -- .3
.3
.5
.5
Eligible operation fits into the remaining time and its predecessors are already assigned.
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Positional Weights
49
Solution to Example 1. Assigning operations
using their task times.
Work-
Work- Time
Time Assign
Assign Station
Station
Station
Station Remaining
Remaining Eligible
Eligible Task
Task Idle
IdleTime
Time
11 1.0
1.0 a,c
a,c aa
.9
.9 cc cc
.2
.2 none
none -- .2
.2
22 1.0
1.0 bb bb
00 none
none -- 00
33 1.0
1.0 dd dd
.5
.5 ee ee
.3
.3 -- -- .3
.3
.5
.5
Eligible operation fits into the remaining time and its predecessors are already assigned.
50
Example 2
0.8 0.6
c d f g h
1.0 0.4 0.3
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Solution to Example 2
a b e
f g h
c d
52
Designing Process Layouts
• Requirements:
– List of departments
• Shape requirements
– Projection of work flows
• One way vs. two way: Packaging and final
assembly.
– Distance between locations
• One way vs. two way: Conveyors, Elevators.
– Amount of money to be invested
– List of special considerations
• Technical, Environmental requirements
53
Example 3:
Locate 3 departments to 3 sites
• Distances: From\To A B C
A - 20 40
in meters
B 20 - 30
C 40 30 -
54
Example 3
• Mutual flow: From\To 1 2 3
1 - - -
2 30 - -
3 170 100 -
• Closeness graph:
1 2
55
Designing Process Layouts
56
Example 3: Layout Alternative 1
30
170 100
1 3 2
A B C
Total Distance Traveled by Material=7600 m
57
Example 3: Layout Alternative 2
170
30 100
1 2 3
A B C
Total Distance Traveled by Material=10400 m
58
Closeness Rating: multiple criteria
59
Muther Grid
• Allow multiple objectives and subjective
input from analysis or manager to
indicate the relative importance of each
combination of department pairs.
• Subjective inputs are imprecise and
unreliable
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Example 4
• Process Selection
Objective, Implication, types
• Product Layout
Line balancing: procedures and measures
• Process layout
Information requirements, measures
From to chart and Muther grid
63
An example for Recitation
Tasks times and predecessors for an operation
Task label Time Predecessors
A 2 None C
B 7 A E
C 5 None D F
D 2 None
E 15 C,D
F 7 A,E A B
G 6 None H N
H 4 B,G G I
I 9 A
J 10 None
K 4 None J
L 8 J,K L M
M 6 A,L K
N 15 F,H,I,M 64
Recitation example
• Find a workstation assignment by taking
cycle time=17 minutes by assigning in the
order of the greatest task time.
• Can you find an assignment that uses only
six stations and meets 17 minute cycle
time requirement.
• See the solution in the next recitation.
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Solution 1: Greatest task time first
Time Idle
A 2 None Station remaining Eligible Assign Time
B 7 A 1 17 C,D,A,G,J,K J
C 5 None 7 C,D,A,G,K G 1
D 2 None 2 17 C,D,A,K C
E 15 C,D 12 D,A,K K
8 D,A,L L 0
F 7 A,E
3 17 D,A A
G 6 None
15 D,B,I,M I
H 4 B,G
6 D,B,M M 0
I 9 A
4 17 D,B B
J 10 None 10 D,H H
K 4 None 6 D D 4
L 8 J,K 5 17 E E 2
M 6 A,L 6 17 F F 10
N 15 F,H,I,M 7 17 N N 2
66
Solution 2: A heuristic
67
Solution 3: Greatest positional weight first
SUCCESSORS'
OPERATION TASK TIME TASK TIME
C 42 5
D 39 2
J 39 10
E 37 15 STATION
K 33 4 STATION NO OPERATIONS TIME
L 29 8 1 C,D,J 17
A 28 2 2 E,A 17
B 26 7 3 K,L 12
G 25 6 4 B,G,H 17
I 24 9 5 I,F 16
F 22 7 6 M 6
M 21 6 7 N 15
H 19 4
N 15 15
68
Practice Questions
• True/False
• General, Job-Shop systems have a lower unit cost
than continuous systems do because continuous
systems use costly specialized equipment.
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Practice Questions
71
Practice Questions
3. A production line is to be designed for a
job with three tasks. The task times are 0.3
minutes, 1.4 minutes, and 0.7 minutes.
The minimum cycle time in minutes, is:
• A) 0.3
• B) 0.7
• C) 1.4
• D) 2.4
• E) 0.8 Answer: C Page: 238
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Chapter 6 Supplement
Linear Programming:
Very useful technique – Learn before graduation
You may read my lecture notes
for OPRE6201 available on the web.
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