Posts: 5
From:Canada
Registered: May 2005

posted May 10, 2008 01:33 PM            

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Is there any company there that produces extruded sheets using wood-plastics composites?

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Posts: 123
From:Silver City, NM, USA
Registered: Jun 2001

posted May 10, 2008 09:57 PM            

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Try contacting twin screw extruder manufacturers like Cincinnati Milacron,American Maplan,Krauss Maffei US,--their sales/marketing people should know if any of their sheet lines are being used for wood composites. All have web sites.

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Posts: 5
From:Canada
Registered: May 2005

posted May 11, 2008 12:36 AM            

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We use Entek twin screw extruder but we have lots of problem on the process.
Main problem is the warpage of the sheets after storing, specially thickness of 3mm and below.
We use 5 mfi polyproylene and rice hulls up to 50%.

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Posts: 910
From:Brodheadsville, PA USA
Registered: Jun 2001

posted May 13, 2008 08:37 AM            

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The sheet warpage sounds like a cooling related issue. It can also be caused by draw at the die or a large rolling bank.

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Best Regards,

Tom Cunningham

www.ExtrusionTechnicalServices.com

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Posts: 5
From:Canada
Registered: May 2005

posted May 14, 2008 12:45 AM            

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Thanks for your advice, Tom.

Actually we don't have any cooling system after the "S" rolls. All our conveying rollers are same sizes. The pull roll is 60 ft away.

We're in the process of looking on solutions of this problem.

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Posts: 910
From:Brodheadsville, PA USA
Registered: Jun 2001

posted May 14, 2008 09:12 AM            

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Warping is caused by;

Different amounts of shrinkage due to different rates of cooling.

Residual stresses due to processing.

Sometime different levels moisture content at different points in the sheet.

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Best Regards,

Tom Cunningham

www.ExtrusionTechnicalServices.com

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