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| Author | Topic: purging between Nylon12 and TPU's |
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jgaver Senior Member Posts: 6 |
posted December 12, 2007 08:42 AM
  
We currently have a 2" extruder with a gear pump at the end used for tubing extrusion. When we switch from our Nylon 12 to our TPU's it takes forever for the nylon to work its way out of our machine even after purging 2-3 times. It shows up in the way of imperfections in our tubing here and there and lasts for approx 200lbs or so, sometimes more. We are assuming that there is still material build up in the gear pump that takes a while to get out. Does anyone have any suggestions on how we can minimize this scrap and lost production time? Any info is greatly appreciated. IP: Logged |
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Tom C Moderator Posts: 899 |
posted December 12, 2007 09:00 AM
Try varying the RPMs of the screw. Make sure the screw is full at low RPMs and then rapidly increase the speed. This allows cooler, thicker resin to scrub the inside surfaces at high velocity. You can try this cycles as many times as needed. ------------------ Tom Cunningham www.ExtrusionTechnicalServices.com IP: Logged |
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jgaver Senior Member Posts: 6 |
posted December 12, 2007 09:09 AM
Thanks for the help Tom. We are going to be making this change-over tomorrow and we're hoping this helps. IP: Logged |
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