Question #1

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?

Question #2

Floor-On, Ltd., operates a line that produces self-adhesive tiles. This line consists of single-machine stations and is almost balanced (i.e., station rates are nearly equal). A manufacturing engineer has estimated the bottleneck rate to be 2200 cases per 16-hour day and the raw process time to be 30 minutes. The line has averaged 1,500 cases per day, and cycle time has averaged 5 hours.

a)      What is the estimated average WIP level?

b)      How does the performance of the average throughput compare to the practical worst case throughput?

c)      What would happen to the throughput of the line if we increased the capacity of bottleneck station and held the WIP at its current level?

d)     If after process improvements the ten machines that required ten workers to run them are no longer needed. Instead five workers are now needed what would you do with the remainder of workers not working on that line anymore? (And please don’t fire them)