T&D electric manufactures high-voltage switches and other equipment for electric utilities. One line that is staffed by three workers assembles a particular type of switch. Currently the threes workers have fixed assignments; each worker fastens a specific set of components on the switch and passes it downstream on a rolling conveyor. The conveyor has capacity to allow a queue to build up in front of each worker. The bottleneck is the middle station with a rate of 11 switches per hour. The raw processing time is 15 minutes. To improve efficiency of the line, management is considering cross-training the workers and implementing some form of flexible labor system.
a) What is the critical amount of WIP that is needed by this line?
b) If the current throughput is 10.5 switches per hour with an average WIP level of 7 jobs what is the average cycle time?
c) What is the practical worst case throughput of the line?
d) Is there any room for improvement on this line?