A plastic injection molding plant will be built to produce 3,000,000 molded parts/yr. The plant will run three 8-hr shifts per day, five days/wk, 50 wk/yr. For planning purposes, the average batch size = 6,000 moldings, average changeover time between batches = 4 hr, and average molding cycle time per part = 27 sec. Assume scrap rate = 2%, and availability for each molding machine = 97%, which applies to both run time and changeover time.
(a) How many molding machines are required in the new plant?
(b) What is the time required to produce each batch?