CASE PROBLEM 17.2 From a Different Perspective They must all be completed before the order can be "And do you have the answer to Problem 6, Pete?" asked shipped. The circles represent operations that must be Professor Grasso. performed to make each product. We've labeled them A1 "Yes sir, I have the answer according to the textbook, for the first operation of product A, A2 for the second op- but I'm not sure I get it," replied Pete. eration, and so on. The numbers inside the circles are the *You don't understand how to get the solution?" machines that are used to perform each operation. We "Oh, I understand the numbers, but I don't know what have only three machines 1, 2, and 3. Your job is to decide they're good for. Where I work, nobody ever sequences the sequence in which the products should be processed anything. You don't have time to calculate things like slack on each machine. There is no setup time between and critical ratio. You do what's next in line or on top of the processes, no inventory on hand, and nothing on order. stack, unless you see a red tag on something that needs to Assume the customer has ordered 50 units of each prod- be rushed through. Or maybe you run what's most like what uct. We'll use a process batch of 100 units and a transfer you've just finished working on so the machine doesn't have batch of one. Make a Gantt chart for each machine to to be changed. Or you run what can get done the fastest show us how quickly you can ship the customer's order. because when you produce more you get paid more." Earliest shipment gets 5 extra points on the final exam." "Pete, it sounds to me like you are using sequencing rules-FCFS, highest priority, minimum setup, and SPT." Pete hesitated. "Maybe you're right, but there's still something that bothers me. If you're going to go to all the Customer trouble to rearrange a stack of jobs, you'd want more in- Order formation than what we're working with." "What do you mean?" "I mean, there's no use rushing a job at one station to let it sit and wait at the next. It's like those maniacs who break their neck to pass you on the road, but they never get anywhere. A few minutes later you're right behind them at a stoplight." "I see." "You need some way of looking at the entire job, where it's going next, what resources it's going to use, if it has to be assembled with something else, things like that." "You've got a point, Pete. Why don't you give us a 'real' example we can work with? You talk, I'll write it on the board." Pete talked for about 10 more minutes, and when he was finished, Professor Grasso had the following diagram on the board. "Okay, class, let's take this home and work on it. A, B. C, and D are products that comprise a customer's order. B C o A3 5 B2 8 C3 3 9 D4 27 AZ 36 B1 3 4 C2 4 D3 1 4 A1 4 C1 15 D2 3 1 D11 2