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| Author | Topic: Wide Spec Material Behavior |
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Shailesh Member Posts: 2 |
posted June 11, 2007 08:40 PM
  
I have 120 mm NRM two stage extruder. Extruder is coupled with a gear pump. The problem is extruder is not stable? Extruder speed jumps from zero to max - suction pressure is not stable? Any suggestion? Thanks IP: Logged |
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Tom C Moderator Posts: 856 |
posted June 11, 2007 09:19 PM
Could be a number of things. Overcontrol of the screw RPMs or a surging extruder. Try disconnecting the gear pump and run some plastic on the floor at something like 40RPM. See if the amps are stable. Measure the output rate. Report back. Try and give us a full set up process conditions from the test.
------------------ Tom Cunningham www.ExtrusionTechnicalServices.com IP: Logged |
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Shailesh Member Posts: 2 |
posted June 12, 2007 07:39 PM
Thanks Tom, I was unable to get this done today. I have scheduled this for Thursday. However following is my set up and our operational procedure. Material used: wide spec extrusion grade HIPS blended with in house regrind (30% regrind) Screen changer to Gear Pump & Die are around 400 to 420 Discharge pressure varies from time to time depending on the material available: 1000 to 1350 PSI Set RPM on Gearpump is 48 - Screw speed varies from 75 to 85 We have noticed that if the material is "good" (No technical backup) extruder behaviour is as above and the sheet is well within the acceptable limits. IP: Logged |
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Tom C Moderator Posts: 856 |
posted June 12, 2007 09:45 PM
Sometimes regrind is the source of the problem because it does not feed well. Perhaps you should test with and without the regrind. ------------------ Tom Cunningham www.ExtrusionTechnicalServices.com IP: Logged |
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