Advanced Thermoforming, 2nd Edition

Chapter 13Changeover of Sheet Machines

Written in cooperation with Manfred Geiss, Geiss AG, Sesslach, Germany

13.1 THE INCREASING IMPORTANCE OF THE CHANGEOVER PROCEDURE

In the thermoforming industry, the same as in many plastics‐processing industries, a rapid changeover of a production machine’s format is becoming increasingly important (Figure 13.1). Manufacturers of thermoforming machines are forced to meet the demand to develop machines that enable the user to effect rapid format changeovers. But what exactly does the term “changeover” mean? The changeover of a machine is the period during which the machine is converted from one format to another format. The time necessary is measured beginning with the outfeed of the last product of the first format until the outfeed of the first product of the second format. In between there are several process steps concerning the changeover procedure:

• Machine standstill
• Cooling
• Dismounting of mold and frame
• Mounting of new mold and frame
• Adjusting of strokes and photocells
• Programming
• Heating
• Start‐up

Figure 13.1 Thermoforming with automatic changeover equipment

(Courtesy of Geiss AG)

As batch sizes decrease, reductions of the changeover times become more and more central concerns. While the complexity of the format parts keeps on increasing, so do the setting parameters in multiples, and additionally the standards of quality. In ...