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| Author | Topic: problems with flood feed |
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fgt Member Posts: 3 |
posted June 17, 2010 01:44 PM
  
Hello, we have a 150mm extruder that runs with HDPE, for pipe extrusion. When testing this machine, we found that it runs well with starve feeding, but it does not run with flood feeding. When trying to run it with flood feeding at above 20rpm, the current shoots up to 380V and the rpm start to decrease. When using starve feeding, the extruders runs well and the current does not shoot up. Does anyone know if it might be a problem with the DC motor? Or might it be a mechanical problem between screw and barrel? or something else? Best Regards IP: Logged |
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Tom C Moderator Posts: 987 |
posted June 17, 2010 01:58 PM
It is probably due to the screw design. As you fill up the screw melting starts earlier as does pressure generation. The extra length of melt and pressure generation will use a lot more power. Try raising the barrel temperatures in the first couple of zones. ------------------ Tom Cunningham www.ExtrusionTechnicalServices.com IP: Logged |
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fgt Member Posts: 3 |
posted June 17, 2010 03:33 PM
thanks for your reply. We have used the following temperatures in the barrel: 190-190-200-200-200 ēC (Celsius) The feed zone in the barrel is not grooved but smooth. Could you please explain me, why would a higher barrel temprature in the first two zones delay the earlier onset of melting? Regards IP: Logged |
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Tom C Moderator Posts: 987 |
posted June 17, 2010 03:53 PM
Onset of melting will not be much affected by barrel temperatures. High initial barrel temperatures will reduce the viscosity peak and associated high power consumption in the beginning of the extruder. Additionally it will reduce pressure buildup bringing available power and output rate into balance. You are doing similar things by starve feeding. ------------------ Tom Cunningham www.ExtrusionTechnicalServices.com IP: Logged |
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