Stepped Disk Extruder

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. 

Viscous drag extruders Drum extruder Diskpack extruder Stepped disk extruder... 

One of the first disk extruders was developed by Westover at Bell Telephone Laboratories it is often referred to as a stepped disk extruder or slider pad extruder [24]. A schematic picture of the extruder is shown in Fig. 2.13. 

A practical disadvantage of the stepped disk extruder is the fact that the machine is difficult to clean because of the intricate design of the flow channels in the stepped disk. 

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 extruders. There are several types of screwless extruders. These machines employ a disk or a drum to plasticate, mix, and extrude. Most designs are based on viscous drag flow. They include Maxwell s elastic melt extruder, Westover s stepped disk and drum extruders, and Diskpack [39]. The Diskpack extruder has the capability of performing all the elementary steps of plastics processing by combination of differently shaped rotating... 

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