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Compounding, Segmented Twin Screws

Mega Brag

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Author	Topic: Mega Brag
Tom C Moderator Posts: 268 From:Brodheadsville, PA USA Registered: Jun 2001	posted December 14, 2003 12:31 PM Seems I'm the only one here with a fascination with mega speed twins, but in case there are others, I'm reporting recent progress. With optimization of screw design, 1500 lbs/hr of first quality PC has been produced on a 47MM fully intermeshing co-rotating twin screw extruder. Total residence time as a melt is calculated at less than 10 seconds. My brag for the day. Tom C [This message has been edited by Tom C (edited December 14, 2003).] IP: Logged
zabielski Senior Member Posts: 259 From:McHenry, IL USA Registered: Nov 2002	posted December 15, 2003 05:58 AM I know of one that does 4 Ton an hour. ZOOM! IP: Logged
Tom C Moderator Posts: 268 From:Brodheadsville, PA USA Registered: Jun 2001	posted December 15, 2003 01:04 PM Ken, What diameter? Tom IP: Logged
zabielski Senior Member Posts: 259 From:McHenry, IL USA Registered: Nov 2002	posted December 18, 2003 06:41 AM 133 mm's. IP: Logged
2beeps Moderator Posts: 65 From:Silver City, NM, USA Registered: Jun 2001	posted December 24, 2003 01:23 AM Tom & Ken--- I'm not real sure about co-rotating twins, but do know that with counter-rotating twins (either converging or diverging as seen from the top), the larger the screw diameter, the faster is the radial velocity on the outer edge of the screws at a given RPM---and this higher velocity translates directly to higher or more severe screw/barrel wear.Thus, calculations relating to economics of output rates must also include screw/barrel replacement costs! Skip IP: Logged
Tom C Moderator Posts: 268 From:Brodheadsville, PA USA Registered: Jun 2001	posted December 24, 2003 09:16 AM Skip, Interesting point. A lot of work has been going into Mega twin screw from the OEMs. My post is more of a technical curiosity rather than an assured economic success. This technical curiosity was acheived by using the latest in twin screw research, process development tools, and personal expereince in the area of mega speeds (500+ RPMs) The 1500 lbs/hr output rate acheived on the 47MM extruder is something quite easy to acheive on a 70MM. Both extruders can make 1500 lbs/hr with 200 HP installed. I doubt if the difference in price of the equipment would make much of a difference in the unit cost of production. At 1500 lbs/hr I'm sure the 47MM is quite stressed, while the 70MM would be well within it's normal range of operation. Where it gets interesting is in the processing of the material. At equal output the 70MM is likely to produce a much cooler melt which expereinces perhaps 3 times more residence time. I'm sure the extruder which produces the higher qwuality product depends on the resin being processed. In my opinion I would prefer to process material on a larger diameter extruder with high torque capabilities so the screws can be run at low RPM. It is just nicer to the material overall. Tom C. IP: Logged

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