In: Statistics and Probability
A production station has a naturally occurring rate of unexpected breakdowns. The mean time between interruptions is 6 hours. The average repair time is 20 minutes, and the CV for repair time is 1.75. The mean natural processing time is 10 minutes with standard deviation 1 minute.
a. What is the effective processing time and the CV of effective process time?
b. If the arrival rate to the station is 5 jobs per hour, what is the station’s utilization?
c. The line engineer decides to try a planned maintenance interruption on the after line every 50 jobs. The maintenance time is 30 minutes (constant). Now what is the effective processing time and its CV? Assume that the maintenance prevents unexpected breakdowns.
d. Before implementing the planned maintenance program, the line engineer determines that she can reduce variability of the repair time. What would be the CV needed for the repair process to achieve the same CV of effective processing time as the planned maintenance alternative?
CV = coefficient of variance