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Unformatted text preview: 0 sec/min 60 sec./unit
desired output units/hr 60 units/hr – Limited by the bottleneck task (the longest task
in a process):
Maximum output available time
3600 sec./hr. 72 units/hr,or pizzas per hour
bottleneck task time 50 sec./unit 7 4/29/2011 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) TM task times cycle time 165 seconds 2.75, or 3 stations
60 sec/station – Always round up (no partial workstations)
– Serves as a lower bound for our analysis 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
Workstation
1 2 3 Eligible task
A
B
C
D
E, F, G
E, F
F
H
I Task Selected
A
B
C
D
G
E
F
H
I Task time
50
5
25
15
15
12
10
18
15 Idle time
10
5
35
20
5
48
38
20
5 8 4/29/2011 Last Layout Calculation
• Step 6: Compute efficiency and balance delay
– Efficiency (%) is the ratio of total productive time
divided by total time
Efficiency (%) t NC 165 sec.
100 91.7%
3 stations x 60 sec. – Balance delay (%) is the amount by which the line falls
short of 100%
Balance delay 100% 91.7% 8.3% AssemblyLine Balancing Objective is to minimize the imbalance between machines or personnel while
meeting required output Starts with the precedence relationships
1. Determine cycle time
2. Calculate theoretical minimum number of
w orkstations 3. Balance the line by assigning specific tasks
to workstations 9 4/29/2011 Copier Example
Perform ance
Time
Task
(minutes)
A
10
B
11
C
5
D
4
E
12
F
3
G
7
H
11
I
3
Total time 66 Task Must Follow
Task Listed
Below
—
A
B
B
A
C, D
F
E
G, H This means that
tasks B and E
cannot be done
until task A has
been completed Copier Example
Perform ance
Time
Task
(minutes)
A
10
B
11
C
5
D
4
E
12
F
3
G
7
H
11
I
3
Total time 66 Task Must Follow
Task Listed
Below
—
A
B
B
A
C, D
F
10
E
A
G, H 5
11 C 7 F B 3 G 4
12 E D 3
11 I H
Figure 9.13 10 4/29/2011 Copier Example
Perform anc...
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This note was uploaded on 12/29/2012 for the course ISE 543 taught by Professor Araby during the Spring '12 term at MSA University.
 Spring '12
 Araby

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