A company is designing a product layout for a new product. It plans to use this production line eight hours a day in order to meet a schedule of 400 units per day. The tasks necessary to produce this product are detailed in the table below

Question

Task Predecessor Time (seconds)
A - 50
B A 36
C - 26
D - 22
E B, D 70
F C, E 30

a. Draw the network described in the table.
b. Without regard to a production schedule, what is the minimum possible cycle time (in seconds) for this situation; what is the maximum?
c. What is the required cycle time (in seconds) in order to meet the schedule?
d. What is the theoretical minimum number of workstations needed to meet the schedule?
e. Balance this line using longest processing time.
f. What is the efficiency of the balance obtained in part e?

Answer 1

The network diagram appears below. Minimum cycle time is 70 seconds (the longest task time); maximum cycle time is 234 seconds (sum of the task times). Required cycle time is 480/400 = 1.2 minutes or 72 seconds (which is barely feasible). The theoretical minimum number of stations required is at least 234/72 = 3.25 or 4.

Station Task Time (seconds) Time left (seconds) Ready tasks
A,C,D
1 A 50. 22. C,D,B
D 22. 0. C,B
2 B 36. 36. C,E
C 26. 10. E
3 E 70. 2. F
4 F 30. 42.
Summary Statistics
Cycle time 72 seconds
Time allocated (cycle time * #) 288 seconds/cycle
Time needed (sum of task times) 234 seconds/unit
Idle time (allocated-needed) 54 seconds/cycle
Efficiency (needed/allocated) 81.25%
Balance Delay (1-efficiency) 18.75%
Min (theoretical) # of stations 4