Question

As part of a major plant renovation project, the industrial engineering department has been asked to balance a revised assembly operation to achieve an output of 240 units per eight-hour day. Task times and precedence relationships are as follows:

Task Duration (minutes) Immediate Predecessor

a 0.2 -

b 0.4 a

c 0.2 b

d 0.4 -

e 1.2 d

f 1.2 c

g 1.0 e,f

Do each of the following:

a. Determine the minimum cycle time, the maximum cycle time, and the calculated cycle time.

b. Determine the minimum number of stations needed.

c. Assign tasks to workstations on the basis of greatest number of following tasks. Use longest processing time as a tiebreaker. If ties still exist, assume indifference in choice.

d. Compute the percentage of idle time for the assignment in part d. Use the actual bottleneck cycle time in your calculation.

Answer 1

The minimum cycle time is 3.2 minutes, the maximum cycle time is 4.6 minutes, and the calculated cycle time is 0.5 minutes per unit. The minimum number of stations needed is 7. Tasks are assigned to workstations based on the greatest number of following tasks, with longest processing time as a tiebreaker. The percentage of idle time for the assignment is 30.4%.

Step-by-step explanation:

The minimum cycle time is determined by the longest path through the assembly operation, which is 3.2 minutes. The maximum cycle time is determined by the sum of all the task times, which is 4.6 minutes. The calculated cycle time is based on the desired output, so it is 240 units divided by the number of minutes in an eight-hour day (480 minutes), which is 0.5 minutes per unit.

The minimum number of stations needed is determined by dividing the longest path (3.2 minutes) by the calculated cycle time (0.5 minutes per unit), which is 6.4 stations. Since we can't have a fraction of a station, we round up to 7 stations.