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| Author | Topic: Vent overflowing |
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Daddyof4 Member Posts: 2 |
posted June 28, 2006 12:26 PM
  
We are trying to run a new standard pvc product on our twin screw and material is fusing and "extruding" out of both sides of the vent opening. We have seen this before on our compounding machine but this one isn't responding to normal tried and true cures. We have tried temperature variations and feeder adjustments but still seeing the overflow problem. Any advice? IP: Logged |
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Daddyof4 Member Posts: 2 |
posted June 28, 2006 01:47 PM
Ok, we finally found the "sweet spot" so the vent would stop extruding its own material. Vent vacuum is increasing well and the part is looking better. Anyone is still welcome to post helpful hints on this subject as all are welcome. IP: Logged |
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rickyconanan Member Posts: 2 |
posted August 12, 2006 05:04 PM
I'd been in wood plastics composite industry for about a year now. We have big problem on the extrudate coming out of vent too. To solve this problem, we installed a vent stuffer in it - a screw pushing down the extrudate to the barrel. It works well until now. If u want more info on this, visit the website of the company called ENTEK. IP: Logged |
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Tom C Moderator Posts: 888 |
posted August 12, 2006 07:28 PM
Ricky, I have some experience redesigning Entek vent diverter plates to eliminate vent flow. This could even have resolved your isuue without the expense of a vent stuffer. Let me know if you are interested via email. ------------------ Tom Cunningham www.ExtrusionTechnicalServices.com IP: Logged |
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XT12UDE12 Member Posts: 3 |
posted August 25, 2007 12:21 AM
I frequently run into this same problem when running straight regrind instead of a powder in a machine that does not have regrind screws in it. I have found that starving the screws with a dosing unit and running the screw speed higher helps to minimize/eliminate this issue. My last day at work I saw a rare example when we ran powder material in an extruder with regrind screws. Oddly the material came rather quickly out of the vent holes. We asked to have plates made to bolt over the vent holes so we didn't have to recycle so much material. We were denied this since we were told that this would create too much head pressure and result in having to slow down the part. I am definitely interested in finding more out on this since we run a lot of regrind and it is not uncommon for us to have as many as 5-6 machines with material running out of the vent holes. This is a huge pain in the butt to keep clean. IP: Logged |
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Tom C Moderator Posts: 888 |
posted August 25, 2007 08:59 AM
What type of twin, a counter rotating conical? ------------------ Tom Cunningham www.ExtrusionTechnicalServices.com IP: Logged |
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