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 A-D-G-H 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 35-2 = 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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This note was uploaded on 03/11/2010 for the course FMIS 3301 taught by Professor Lievano during the Fall '09 term at University of Minnesota Duluth.