An average of 20 new orders are started through a certain factory each month. On average, an order consists of 50 parts that are processed sequentially through 10 machine-operations in the factory. The operation time per machine for each part = 15 min. The non-operation time per order at each machine averages 8 hours, and the required setup time per order = 4 hours. There are a total of 25 machines in the factory working in parallel. Each of the machines can be set up for any type of job processed in the plant. Only 80% of the machines are operational at any time (the other 20% are in repair or maintenance). The plant operates 160 hours per month. However, the plant manager complains that a total of 100 overtime machine hours must be authorized each month in order to keep up with the production schedule.
Determine the following:
(a) What is the manufacturing lead time for an average order?
(b) What is the plant capacity (on a monthly basis) and why must the overtime be authorized?
(c) What is the utilization of the plant according to the definition given in the text?
(d) Determine the average level of work in process (number of parts in process) in the plant.