posted February 09, 2004 01:53 PM               

Welcome to the single screw extrusion forum, thanks for joining

Barrel screw clearance, when new, depends on the size of the eztruder. There are no hard and fast rules to apply to determine what the maximun clearance is- but basically, when you are getting an unacceptable level of gelling, unexplainably high melt temps, and large decreases in output.... Then off to the screw rebuilders it goes.

Keeping track of output rates is one way of keeping tabs on where the screw is at (wear wise), and measuring when ever its stripped down for cleaning.

posted February 22, 2004 09:18 PM               

Flight clearance depends on diameter.
It must include the effects of barrel diameter variation, barrel straightness, screw machine tolerance, screw straigthness, and thermal expansion.

Too large a clearance in the pumping section leads to high melt temperature (or lower barrel temperature), increased speed, and lower output. Sometimes gels will also result from excessive clearance with PE. So, you may see short filter life.