Continuous disk extruders

There are several extruders that do not use an Archimedean screw for transportation of materials, but still belong to the category of continuous extruders. These machines are sometimes referred to as screw-less extruders. Usually they employ a disk or a drum. Most disk extruders are based on viscous drag transport principle. To this category belong stepped disk extruders [Westover, 1962 Raleigh, 1879], drum extruders, spiral extruders [Ingen Housz, 1975], diskpack extruder [Tadmor, 1979, 1980 Tadmor et al, 1979, 1983 Hold et al., 1979 Valsamis, 1983], and many others. 

There are a number of extruders, which do not utilize an Archimedean screw for transport of the material, but still fall in the class of continuous extruders. Sometimes these machines are referred to as screwless extruders. These machines employ some kind of disk or drum to extrude the material. One can classify the disk extruders according to their conveying mechanism (see Table 2.1). Most of the disk extruders are based on viscous drag transport. One special disk extruder utilizes the elasticity of polymer melts to convey the material and to develop the necessary diehead pressure. 

If exit channels are incorporated into the stepped disk, the polymer can be extruded in a continuous fashion. The design of this extruder is based on Rayleigh s [25] analysis of hydrodynamic lubrication in various geometries. He concluded that the parallel stepped pad was capable of supporting the greatest load. The stepped disk... 

Disk Feeder n A horizontal, flat or grooved, rotating disk at the bottom of a hopper feeding a continuous extruder that controls the feed rate by varying the speed of rotation of the disk, or by varying the clearance between the disk and the scraper that directs the feed from the disk into the feed throat of the extruder. 

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