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Author Topic:   BURNING LINES
slkoli
Senior Member

Posts: 9
From:pune,maharastra,INDIA.
Registered: Jan 2005

posted December 06, 2005 03:02 AM     Click Here to See the Profile for slkoli   Click Here to Email slkoli     Edit/Delete Message   Reply w/Quote
WE HAVE PROBLEM OF BURNING YELLOW LINES ON PROCESSING PVC SHEETS(RIGID,FOAM).BURNING LINES OBSERVE ON CENTRE OF THE TOP SURFACE AFTER 4-8Hrs OF M/C RUNNING.WE PROCESS LEAD STABLIZER BASED PVC COMPOUNG.WE OBSERVED PLATE OUT IN ADAPTORS UPPER PART & MATERIAL STICKING ON THE SCREW TIP. WE HAVE A NEW BARREL,SCREW,ADAPTOR & T-DIE.THESE PROBLEM DOESN'T ARISE WHEN WE USE TIN STABLIZER.
WE HAVE A COUNTER ROTATING,PARALLEL TWIN SCREW EXTRUDER,THEYSHON MADE.PL.HELP ME IN SORTING THESE PROBLEM. A CHANGE IN ADAPTOR DESIGN OR IN FORMULATION MAY HELP?
BELOW IS THE FORMULATION:
1.RESIN K-60=150kg 2.processing aid=12kg 3.caco3=6kg 4.Tio2=6kg 5.Esdo(soyaoil)=2.5kg 6.Lead stablizer(LS+DBLP+TBLS)=8kg 7.lubricant(wax-1.8,G741-.7,Ac-.4,stearicacid-.5kg) 8.calcium stearate-.8kg

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Tom C
Moderator

Posts: 661
From:Brodheadsville, PA USA
Registered: Jun 2001

posted December 06, 2005 10:53 AM     Click Here to See the Profile for Tom C   Click Here to Email Tom C     Edit/Delete Message   Reply w/Quote
Seems that many extrusion machines that process PVC have resolved the screw tip problem by using elongated and flighted screw tips.

Additionally propoer adaptor and die design will supply sufficient surface shear stress to keep the surfaces moving and clean.

------------------
Best Regards,

Tom Cunningham

Extrusion Technical Services

www.ExtrusionTechnicalServices.com

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slkoli
Senior Member

Posts: 9
From:pune,maharastra,INDIA.
Registered: Jan 2005

posted December 08, 2005 02:52 AM     Click Here to See the Profile for slkoli   Click Here to Email slkoli     Edit/Delete Message   Reply w/Quote
Thanks Tom for your reply,could you pl.explain what happen when three different temp.act at adaptor/metering area,we keep adaptor temp.at 155 c,meteringzone-180c & screw temp.-160c.And why the bottom surface of the adaptor remains clean and upper surface observe rough?

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Tom C
Moderator

Posts: 661
From:Brodheadsville, PA USA
Registered: Jun 2001

posted December 10, 2005 10:02 AM     Click Here to See the Profile for Tom C   Click Here to Email Tom C     Edit/Delete Message   Reply w/Quote
This is my guess;

You indicate plate out in the adaptor rather than burning, which would indicate cool temperatures.

The adapotr temperature is set low, so possibly the adaptor heater never need to come on.

Thermocouples are often installed on the underside of adaptors, and may be indicating a temperature which is much higher than the top of the adaptor.

So there is a potential that the top area of the adaptor is too cold. Try raising the adaptor temperature.

Good luck.

------------------
Best Regards,

Tom Cunningham

Extrusion Technical Services

www.ExtrusionTechnicalServices.com

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louis33
Senior Member

Posts: 141
From:Allentown, PA - USA
Registered: Jun 2001

posted December 12, 2005 08:16 AM     Click Here to See the Profile for louis33     Edit/Delete Message   Reply w/Quote
Tom

I think there may be a temperature difference between the top and the bottom, but I'm not sure of the reasoning behind that.

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