11 Extrusion.ppt

Extrusion MFG 355 Extrusion Extrusion System Extruder Extruder Drive Motor Turns the Screw Provides power for the process Thrust Bearing Prevents the screw from moving backward Seals off the end of the barrel Extruder Screw Connected to drive linkage Inside barrel Grinds the plastic Moves the plastic Extrusion Screws Extrusion Screws L/D ratio Relates directly to the extruder’s ability to mix Typical L/D ratio is 16:1 up to 32:1 Newer machines tend to have higher ratios Extrusion Screws Extrusion Screws Extrusion Screws Zones Extrusion Screws Varying screws for different resins/applications Multi-Screw and Multi-Barrel Valuable in heat sensitive material processing (PVC) Increases efficiency in moving material More positive pumping action Multi-Screw and Multi-Barrel Co-Rotating Screws Counter-Rotating Screws Advantages and Disadvantages Head Zone The portion of the machine at the end of the barrel Holds/contains the die Head Zone Head Zone Breaker plate Screens Filters Adaptor Die mount Adaptor Laminar flow or turbulent flow Adaptor Laminar flow or turbulent flow Die The “mold” for the extrusion process Die Die Dies are cut to produce a certain profile Cutout will probably not match the finished product Spider Die Spider Die Spider Dies Coat Hanger Dies Correct flow Velocity Distribution Wire Coating Dies Wire Coating Dies Wire Coating Dies Dimensional Control Part Dimension Control Die Sizing plate Air pressure Cooling (shrinkage) Speed of pull Pullers Pullers Pullers are in contact with cooled material Pulling quicker will decrease the cross-sectional area of the extrudate Film Blowing Extrude a “tube” upwards through vertical die Inflate “tube” till it becomes a film Collect film and process as needed Film Blowing Film Blowing Film Blowing Film Blowing Systems Film Blowing Film Blowing Dies Film Blowing Printing/Cutting/Sorting Film Blowing Coating of Paper and Fabric Extrude a film System of rollers to apply extruded film to paper/fabric Windup rollers