posted 06-13-2001 08:42 AM
There are several possible reasons for feed throat cooling. Different reasons may apply depending on the circumstances:
1) Keeps heat away from the extruder drive train and bearings. 2) Prevents the throat opening and hopper from getting hot and causing materials to stick and stop flow. 3) In some extrusion situations a cool throat will promote solids conveying. 4) In some extrusion situations a hot throat surface may prematurly melt material. The screw scrapes off the material, and if the screw is cool enough the material will freeze on it. This will give the screw a rough surface which will seriously compromise solids feeding in some situations. 5) Throat cooling can help minimize temperature buildup of the screw section in the feed throat while the extruder is idle, but hot. If the screw heats up in the throat while idle, starting up could be a problem. Resin could melt to the screw surface, and then freeze as more entering material cools the screw. This will cause of lot of feeding problems later.
Tom @ CCS
[This message has been edited by Tom C (edited 06-14-2001).]
posted 06-12-2001 08:28 AM
