posted October 01, 2003 11:40 AM               

I would like to know, if I was compounding PVC (Shore A hardness between 70 to 90) on a 24/1 LD single screw extruder and would like to have a new screw made, which is the most preffered screw design to use. There are several options :

1. Use a general purpose screw
2. Use a general purpose screw with maddox head
3 . Use a barrier screw with or w/o maddox head

I was under the impression that barrier screw are typically used for pellet compounding. I also know that most of the PVC compouning is shifing towards twin screw extrusion. Please advise.

Thanks,
VK

posted October 01, 2003 07:05 PM               

If your objectives are lots of mixing and your material is thermally stable, then the more components on the screw the better.

If your objective is to get the material through the screw with a minimum of heating, fewer components are better.

With a little more detail we can probably help.