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B 10
(6)
C 4
(15)
F 4
(15)
G 8
(7.5)
D 8
(7.5)
H 7
(8.6)
E 6
(10)
FMIS 3301
FLOW TIME AND CAPACITY
(Critical Path and Bottleneck)
Suppose a process has the following structure.
The numbers next to the activity labels are processing
times (T
P
) in
minutes.
The numbers in parentheses are capacities per hour.
Notice how much
information is required to evaluate whether a change in T
P
affects flow time, capacity, or both.
The critical path is ADGH with a length of 35 minutes, so theoretical flow time is 35 minutes.
The smallest capacity is in A, so it is the bottleneck.
Process capacity is 5 units/hour.
Note that the
bottleneck (BN) is on the CP.
Suppose it is desirable to decrease the flow time by 2 minutes.
That can only be achieved by reducing the
processing time of one or several activities on the CP by 2 units.
For example, reduce the time of D by 1
and of G by one.
•
What is the process flow time? New CP length is 352 = 33 minutes (there are now 3
CPs).
•
What is the process capacity? 5 units/hour, since the bottleneck is was not modified.
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 Fall '09
 Lievano

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