Tadmor and Klein Model

The model could be used to either calculate the pressure gradient or pressure at the end of the conveying section for a specified rate, or it can be used to calculate the rate for a specified pressure gradient or section exit pressure. 

Two issues have been found with this model that limits its utility 1) the model is very sensitive to the ratio of the barrel and screw friction factors and does not work well if at all when the screw friction factor is higher than that for the barrel. 

Tadmor and Broyer [16, 17] produced two more solids conveying models a modified version of Tadmor s earlier model [1], which assumed isothermality [16], and a second model that allowed for thermal effects [17]. Later, a model by Strand et al. [18] was developed based on the Tadmor-Klein model for starve-fed solids conveying. 

Like the original Darnell-Mol model, the Tadmor-Kleln model was developed with only very limited rate data because solids conveying measuring devices were not available at that time. Moreover, dynamic coefficient of friction data were also unavailable during their model developments. Complete plastlcatlng extrusion simulations, however, were developed with the Tadmor-Kleln model using engineering friction coefficients to estimate the characteristics in the process. 

---

The new melting model presented in this section qualitatively fits the experimental data observed by many previous researchers. Like the Tadmor and Klein model [8], this model is based on simplistic assumptions and linear mathematics for the melt films. The new model, however, does not require the reorganization of the solid bed like the Tadmor and Klein model. Furthermore, the new model allows viscous dissipation and melting in all four melt films, and does not restrict all melting to the Zone C film. Melting in the Zone D melt film becomes highly important when the boundary conditions are switched from barrel rotation to the actual conditions of screw rotation. 

---