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| Author | Topic: PET screw design |
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seref Member Posts: 1 |
posted January 18, 2005 04:50 AM
   
I'd like to have an advice! Now i am trying to design a PET screw. It will be 36 L  with vent and a mixing torpedo. But instead of smooth barrel I want to try a grooved feed section. So as to decrease the pressure in this section pitch will be less than 1 D, the rest of the screw pitch will be more than 1 D.Can i dare? IP: Logged |
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Tom C Moderator Posts: 436 |
posted January 18, 2005 07:39 AM
Seref, Be careful as the low pitch in the feed section is likely to increase pressure rather than reduce it. Any feed section has the potential to deliver much more material than the rest of the screw can handle. In a grooved feed section you must reduce the depth a great deal if you want to balance the feed with the rest of the screw. You could combine a shallow feed with a reduced pitch, but the primary rate reduction will come from the reduced depth. Typically I see good feeding and extrusion rates with PET. By using grooved feed with a hard resin like PET you risk upsetting the process, increasing pressure variation, screw and barrel wear, running out of torque and barrel rupture. What is your output vs. RPMs and barrel diameter? I could tell you where you stand in terms of rate potential. Tom C IP: Logged |
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