This preview shows pages 1–3. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: 52 TOURB AJob Shop ers, so that they knew precisely which job would go next to every machine, who would work that job, and when they would start on it. As Joe Gehret put it: "Scheduling is the most difficult function we have around here. It's the easiest thing in the world to say no to a customer, that we can't fit his job into the shop. But after a few noes, you may not have a customer." During recessions, scheduling was even more difficult than usual. The drop in orders then meant that the foremen had fewer chances to group compatible or- ders together to avoid bottlenecks or to create labor-saving opportunities. In busier times, the foremen could choose among the many orders in the shop, spreading out demand for particular pieces of equipment and taking advantage of the economies possible. Frequently, planned schedules had to be interrupted because of customer de- sires for expedited delivery, because materials were received late from the cus- tomer, or because of the breakdown of the machine or its tooling. In these cases quick, remedial action had to be taken. Often, this remedial action took the form of adding a new job or rerouting an existing job through the shop. Noreen had enough equipment on hand, typically, to permit a new or rerouted job to be set up on an unused machine. Joe Gehret purchased new machines for the shop with this kind of compatibility in mind. Not all jobs, of course, could be rerouted through the shop if things went awry,but it was possible with a sizable number, especially those that were not too complex. Some jobs could even be machined in an alter- native sequence (e.g., milling could be done first rather than third), and this helped when remedial action was necessary. In general, the foremen preferred to have lathe work performed first, then milling, and only then grinding; but they were willingto abandon this sequenceif necessary. . Some aspects of just-in-time manufacturing had repercussions for machine shops such as Noreen. Customers were now placing orders that required multiple, A Hurco machining center. (Courtesy of Noreen Industries) TOUR B AJob Shop S3 10 it: :st p. time-phased deliveries of smaller-than-usuallots. Even though many of Noreen's new machines were capable of running small lots economically, this trend did serve to complicate scheduling. ., Technological Advances and Other Trends Over the years, technologjcal advances, especially in computers, have been revolu- tionizing the machine tool industry. The old fully manual lathes, mills, grinders, and other tools had been supplanted by a succession of newer tools: 1. The first set of newer tools were NC (numerically controlled) machines that could repeat operations exactly by reading punched paper tapes. The paper tapes had to be specially prepared and thus were typically suitable for only high-vol- ume, repetitive jobs. Naturally, in job shops like Noreen with many low-volume, one-of-a-kind jobs, NC machines could find only limited use....
View Full Document