Underwater Pelletizing

Modified on Thursday, 26 February 2015 04:34 PM by mpieler — Categorized as: Extrusion Hints

Underwater Pelletizing
Vol. 35 #1, Winter 2010

One of the challenges with underwater pelletizing is having the correct number of die holes for the process to ensure that all the holes stay open. Obviously you can run with freeze off but this will result in non-uniform heat distribution in the die plate which in turn can create opportunities for additional problems in pellet uniformity. A simple calculation to determine the number of open holes = Throughput (lbs/hour) X 7.6 / (the weight per pellet(g) X number of knives on the hub X speed of the pelletizer (rpm)). It is a good idea to weigh at least 100 pellets and take average for the weight per pellet. If more than 10% of the die plate holes are fro- zen, try increasing throughput or plugging holes.

- Tom McHouell, Polymers Center of Excellence

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