Air entrapped inside extruder

[lukin1977]

During the extrusion of welding electrodes we have air entrapped inside the extruder jacket and we need to eliminate this air.
The extruder is an hydraulic cylinder. See picture attached
Does anyone have any idea about how to solve this?

 

[bigTomHanks]

http://en.wikipedia.org/wiki/Plastics_extrusion

http://www.vosbltd.com/images/Extrusion Defects/pdf2.PDF

http://articles.ides.com/processing/jb_sinks_bubbles.asp

Sounds like a vent could not be working properly or too much/incorrect decompression is taking place. Also moisture could be come trapped and as the material heats up it produces steam bubbles.

 

[chicopee]

Is this extruder for a coating operation of the welding wire? If so, load up the hopper with the coating material and sacrifice a lot of coated wire until the air is completely gone and during the next and subsequent extruding operations make sure that the hopper does not go empty.