PVC wont feed into the barrel

[Encap1]

We started up a mold that runs with PVC. We are surface drying the PVC at 165. When we introduce the PVC into the barrel, we can run a couple of shots, then the pvc quits feeding into the barrel. After a while it finally charges all of the way, then it wont feed again the next cycle. Then I put some purging compound into the hopper and it purges just fine.

We noticed that when we take the magnets out from the hopper, that they are oily. I drained the hopper and the pvc that came out was oily. So I drew the PVC straight from the gaylord and bypassed the dryer and everything worked fine.

Why would the PVC become oily in the dryer and why would that keep it from feeding into the barrel.

[brentb]

Grade of PVC? Additives? You talking°F I hope?

KOM

brent

[rickbatey]

PVC doesn't need to be dried. Your heat is probably cooking oils or plasticizers out and causing the pellets to stick to the screw. What is the compression ratio of the press? Too high and you can cause excessive shear heating.
Rick.

[Suhas]

Agreed with Rick, you may want to use a drying temp of may be just 80-90 deg F or so. You will be fine. Also remember that PVC usually has a lot of additives to it for plasticizing, heat and melt stability, etc.
Suhas

[brentb]

Starve feeder?

KOM
brent