Question

An automated car wash serves customers with the following serial process: pre-treat, wash, rinse, wax, hand dry. Each of these steps is performed by a dedicated machine except for hand-dry step, which is performed manually on each car by one of three workers. The steps of the process have the following process times:-pretreat: 1 minute per car-wash: 5 minutes per car-rinse: 2 minutes per carwax: 3 minutes per carhand dry: 8 minutes per cara. If the car was has a demand of 15 cars per hour, what is the flow rate of the process?b. if the car wash has a demand of 15 cars per hour, what is the utilication of the machine that performs the wax process?

Answer 1

a) 12 customers per hour is the flow rate of the process.

b)  if the car wash has a demand of 15 cars per hour 60 percent   is the utilization of the machine that performs the wax process.

Explanation:

a) The bottle neck which is the process of washing has a capacity of  12 number of cars as its minimum capacity. The flow rate is considered as the minimum capacity of the bottleneck. Thus, flow rate of the process will be 12 customers per hour.  

b) The utilization capacity can be calculated by dividing  flow rate by  the capacity of the process step.

Here the demand is 15 cars per hour. The calculated flow rate is 12 cars per hour.  The difference is 3.

Thus the capacity of the machine which performs the wax process will be  1 / 3 × 60 = 20 cars per hour.

Thus the utilization of this machine is 12 / 20 = 60 percent.

Utilization is the flow rate divided by the capacity of the process step.