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 Extrusion, Twin Screw
 Problem With Powdered PVC Lubricant on 1st Downstream Vacuum Sizer Causing Jamb-ups
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| Author | Topic: Problem With Powdered PVC Lubricant on 1st Downstream Vacuum Sizer Causing Jamb-ups |
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XtruDR Member Posts: 1 |
posted February 28, 2007 01:14 PM
  
Having problem with powdered PVC lubricant on 1st downstream vacuum sizer causing jamb-ups. Extrusion is a rigid PVC profile on a vented Krauss-Maffei KMD-90 vented twin-screw. Die and tooling were designed to run at 415°F to get speed necessary for profitability -- however, powdered PVC material is rated at 390°F max. Intriguing thing is that sometimes the system can run a week without a jambup, next time it occurs every couple hours. Have looked at all available data in KMD-90 C4 controller, but do not see any anomalies that could be correlated to jambup frequency. Am considering looking at powder chemical and physical properties and particle size and consistancy. Any guidance on where or what to look at would be appreciated! IP: Logged |
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XT12UDE12 Member Posts: 1 |
posted August 25, 2007 12:05 AM
Assuming that there are no material issues, after the first jamb-up do you open the vacuum sizer to check for any obstructions? In my experience after running a profile for an extended period of time (4 days to a week) a waxy buildup forms in the vacuum slots in the sizer.Without clearing these slots you will be prone to more frequent backups. Some materials leave more wax than others. I run one material that clogs a sizer twice as fast as another simply because it is missing an impact modifier. IP: Logged |
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