Flow mechanisms in the extruder

The following equation represents a flow mechanism [5] at the metering section of the extruder 

Reprinted with permission from R. Brzoskowski, J. L White, F. C. Weissert, N. Nakajima and K. Min, Rubber Chemistry and Technoiogy, 1986, 59, 4, 634. 

When the channel geometry is not rectangular a geometric factor, f, is applied. When the die is attached and if a part of the material movement is a reverse flow, case A, the actual cross-section of the forward-moving material will be smaller than wh. If the entire material is moving forward, the actual forward velocity is smaller than V.  

In this case is a slip or a slip-stick mechanism operating to decrease to Vf  

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