Extruder operation shutdown

Figure 11.12 Photograph of a screw that had numerous shutdowns where the extruder was maintained at operating temperatures for an extended time. The extruder was purged prior to removing the screw, yet dark degraded resin covers most areas of the screw...

The commercial extruder was modified by tapering the entrance to the new barrel such that a ledge did not occur between the feed casing and the barrel. As predicted by the experimental research, the commercial line was able to operate stably and at a high specific rate of 4.2 kg/(h-rpm), and at a screw speed of 150 rpm the plant was operating at a rate of 630 kg/h. Plant personnel ordered a new feed casing and planned to Install the casing at the next planned shutdown. 

In-line thermoforming production lines, particularly those being fed directly from an extruder, have to be completely synchronized, or inferior parts result, and/or the cost of the operation goes up. For example, if the trimmer operation has to be slowed down, the extruder output has to be reduced. In fact, a slowdown can result in a shutdown if the extruder cannot operate at the slower speed required. All functions and stations have to be properly interrelated. 

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