Quarterly Magazine

Second Quarter 2016

Thermoforming Technical Problems I Wish I Could Solve: Wall Thickness Variation by Jim Throne
First off, let’s be practical about thermoforming. It suffers from two afflictions. Unlike the injection molding process with its pellet-to-product procedure, we gotta make sheet first. And unlike that same process, a whole bunch of our hot sheet winds up as non-product. Meaning, of course, that we need to reprocess the non-product into more sheet. One of my earliest childhood memories is watching my German grandmother make her legendary cookies – rolling out the dough and cutting the pfeffernusse disks from it with a water glass. She’d remold and reroll the skeleton before repeating the cutting process…

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Second Quarter 2016

Troubleshooting Gear Pump Assisted Single-Screw Extrusion Processes by Mark A. Spalding and Wenyi Huang, The Dow Chemical Company, Midland, MI, Daniel Smith, Maag Automatik, Inc., Charlotte, NC, and Gregory A. Campbell, Clarkson University/Castle Associates, Jonesport, ME
Gear pumps are often used in tandem with single-screw extruders to increase rate, decrease resin consumption, improve process stability, decrease extruder discharge pressure, and decrease the extrudate temperature. When a process is unstable, it is often not obvious if the extruder is unstable and the gear pump is operating well, or the extruder is operating well and the gear pump operation is unstable…

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