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Solid-State Motor Control Using Phase Controls
Published in Sylvester J. Campbell, Solid-State AC Motor Controls, 2020
A typical metal stamping press may be driven by a constant-speed ac motor, through a 3:1 or 4:1 mechanical speed changer. The speed changer is adjusted to maintain maximum throughput for the various stamping requirements. Considerable starting and stopping may be required to clear plugs and to change dies. If the mechanical speed changer has a 3:1 ratio, the inertia that the motor “sees” on starting can vary by 9:1 (as the square of the gear ratio). The resulting starting and accelerating torques, reflected into the stamping press, will change in the same proportion, with corresponding effects on wear and rear on the mechanical parts. A solid-state starter with voltage ramp up-time and a ramp-hold feature (in case the control goes into current limit) is an ideal solution to this type of application.
Analyzing Variability
Published in Erick C. Jones, Supply Chain Engineering and Logistics Handbook, 2020
Symptoms: the customer shipment was not delivered on time. Why?—Die stamping press broke down resulting in running out of parts,Why?—Lack of scheduled maintenance of the press for a period of three months,Why?—Reduction of maintenance department staff from 6 to 8.Why?—Maintenance department budget shot up due to overtime costs and the General Manager required a reduction in costs of overtime for all overhead support departments.Why?—Removal of unnecessary spending by the CEO because company was not reaching profit goals. So, the root cause was the CEO being worried about getting fired for poor profit performance.
The Pattern: Flow, Pull, and Heijunka
Published in Ledbetter Phil, The Toyota Template, 2018
And, of course, building in batches is another obvious situation where buffers are required. Some products in production are pulled one at a time, or one-piece flow, through the plant. But many parts must be built, and subsequently pulled, in batches. This situation exists with a machine that makes large quantities of multiple part numbers. A stamping press is a good example. A press can make many parts quickly, but the dies/material must be changed out when a different part number is made. Making one piece at a time makes no sense here. A press may make 40 different part numbers for an auto. The questions for the press operator are which part number should be made, when should it be made, and how many should be made? (Right part, right quantity, right time.) In push systems, a schedule is used to make this determination, and we’ve covered the timing and other problems with schedules. In 1956, I toured U.S. production plants at General Motors, Ford, and other machinery companies. But my strongest impression was the extent of the supermarkets prevalence in America …. we made a connection between supermarkets and the just-in-time system …. From the supermarket we got the idea of viewing the earlier process in a production line as a kind of store.16
Advanced sensor-based maintenance in real-world exemplary cases
Published in Automatika, 2020
Michele Albano, Luis Lino Ferreira, Giovanni Di Orio, Pedro Maló, Godfried Webers, Erkki Jantunen, Iosu Gabilondo, Mikel Viguera, Gregor Papa
A stamping press (Figure 8) is a metal working machine used to shape or cut metal by deforming it with a die. This use case focuses on press machine maintenance, monitored continuously by a broad and diverse range of intelligent sensors that keep track of its operational conditions.