Nanjing GIANT Machinery Co.,Ltd.

An Single Screw Extruder for use in processing polymeric material is typically composed of, Twin Screw Extruder a cylinder having one or more raised ridges (a "flight") helically disposed thereabout, which gear pump rotates within an annular cylinder, or barrel. The surface of the above which the flight(s) are raised is the root of the.sheet production extruder.A hopper directs polymeric material through an opening in the barrel into contact with and into the space between the flight(s) and the interior wall of the barrel of the extruder.

The gravimetric feeder typically has an initial or feed section which begins the process of conveying the solid polymeric material forward within the barrel of the, the direction of travel of the polymeric material as it is transported away from the hopper by being considered the "downstream" direction. The feed section of is typically followed, with or without other intervening sections, by a transition or melting section in which plastication of the polymeric material occurs. Plastication of the polymeric material occurs as a result of the combined effect of heat produced by heater bands mounted on the outside of barrel and the shearing forces to which the subjects the polymeric material causing friction between the internal wall of barrel and the polymeric material. The melting section of typically followed, again with or without other intervening sections, by a metering section which functions to pump the plasticated material, out through the downstream end of which is typically a die or some other form of restricted orifice.

Polymeric materials having different bulk densities behave differently in the melting, or plastication, section of pecifically because of the different bulk densities. When polymeric material is plasticated, the plastication mechanism involves compacting the material to obtain frictional contact of the material with the interior wall of the barrel. Materials of higher bulk density cannot be compacted as easily or readily as those of lower bulk density, and conditions which are appropriate for the compaction of one material are often not appropriate for another material or for a mixture containing that other material. The amount of difference in the bulk densities of two materials which may cause different compaction behavior is typically at least 20 percent (determined as (ρ ₁ -ρ ₂ )/100/ρ ₂ , where ρ ₁ is greater than ρ ₂ ) may be at least 50 percent, is often at least 100 percent, and may on occasion be at least 1000 percent. A first step toward designing plastication conditions appropriate for polymeric materials having different bulk densities is to classify those materials according to the effect of bulk density on compaction behavior Single Screw Extruder.