Flow in the Extrusion Die

FIGURE 13 3 Flow of ceramic paste between two flat plates under the influence of a pressure gradient. Both the shear stress, and velocity, v, profiles are ven. 

Using the rheology of the ceramic system, we can write in terms of the velocity gradient dvjdx. Then, by integration, the velocity profile can be obtained. These velocity profiles for Newtonian, Bingham plastic, and Crossian rheology follow. 

These velocity profiles are used to determine two key factors the average flow rate and the shear stress at the wall. The average velocity, v, is obtained using the following integral  

The shear stress at the wall is used to determine the thickness of the hardened metal die necessary to withstand the forces acting on it. 

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