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- Peter J Stewart-Hay, Ing Adel Marzouqa replied to the topic 'Running XLPE on a PVC Extruder' in the forum.Hello again,
This is a pretty complicated subject.
PVC screws are designed for high output without burning the PVC. They have deeper channels than PE screws to provide sufficient mixing without high shear.
XLPE extruder screws are designed for low shear and a stable melt pool but stay away from Maddock, Egan, Pineapple and Pin type mixing screws.
I suggest you first read about barrier screws at:
and then get a quotation for the latest cable XLPE barrier screw design from Maillefer at:
Provide them with the complete information on your extruder and PVC screw. Then ask them to give you a sketch of their quoted XLPE barrier screw.
- Hello Adel,
Heat and pressure along with the residence time are the issues causing the XLPE mixture to crosslink.
Although a PVC screw has a deeper pressure section and a modified mixing section to help prevent the PVC from burning, it is really not the ideal screw for mixing and pumping the mixed and now liquefied XLPE compound.
Likewise your extruder has a 25 to 1 length to diameter ratio and a 4.72 diameter screw. I suspect that you have been insulating line wire (Secondary distribution cable.) with this machine. You probably also use water on the screw to reduce the chance of burning the PVC.
As long as you use accurate control of the screw temperature, keep the residence time low, keep to the recommended temperature for the XLPE compound and don't shear the XLPE too much, you will have a reasonable chance of being able to properly extrude the XLPE compound. If this does not work, you will have to invest in a proper XLPE screw with a barrier section before metering.
All will depend on the product you will be manufacturing.
An experiment is in order along with a careful examination of the screw, crosshead, tooling and product after the experiment is over.
- Hello dear..
First of all I want to thank you for your effort in this great forum.. This will be my first post here
I wanna discuss this issue related to running XLPE; Is it possible to run XLPE on a PVC extruder and PVC screw? What are the main risk that may result.
Extruder: TR120 25:1
Compound: a silane grafted polyethylene + Black catalyst (carbon black pigment)
ratio of catalyst is 11 wt%
Awaiting to find your reply