Consider a two-stage pull production process where demand for the final output is either 5, 7 or 10 units every hour. Demand is never the same for more than 3 consecutive hours. The process time at the second stage is 6min/unit while the first stage can process 9 units per hour. Each shift is 8 hours long.

a) What is the worst-case scenario for the first stage over an 8 hr. shift?

b) Suppose management does not accept any demand to go un-met. How many Kanbans are then needed in the buffer between the two areas?

c) What is your answer to b) if the process time at the second stage is reduced to 4min/unit?