The Ingen Housz Screw

The Ingen Housz screw combines a barrier geometry with multi-flighted geometry to obtain significant improvements in melting. A picture of the barrier section geometry is shown in Fig. 8.62. 

The barrier section geometry is shown with the screw channel unrolled onto a flat plane. The solid bed is divided into several parallel solid channels. The melt is collected in several parallel melt channels. It is possible to achieve this multi-flighted geometry by a significant increase in the helix angle. The total melting length can be expressed as [27]  

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The characteristics of the various barrier screws are summarized in Table 8.1. The Maillefer screw has many desirable characteristics despite the fact that its melting performance is not quite as good as the other barrier screws. The Ingen Housz screw clearly has the best melting performance however, this is at the expense of geometrical simplicity. 

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. 

The following analysis of the melting performance of various barrier screws is based on the analysis developed by Meijer and Ingen Housz [27]. This analysis provides a clear and logical approach to the determination of the melting capacity as a function of the barrier section geometry. 

Again, the melting performance can be analyzed by the procedure used for the Maillefer screw. Because of the continuously varying helix angle, the analysis is rather involved. Ingen Housz and Meijer [27] found for the total melting length of the Kim screw ... 

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