Power Consumption in the Melting Zone

The mechanical power consumption in the melting zone can be determined by breaking down the power consumption in three parts the power consumed in the melt film dZ the power consumed in the melt pool dZ p, and the power consumed in the clearance between flight and barrel dZ. The power consumed in shearing the melt film Is described by  

It is assumed that the flow in the melt film is a drag flow, i.e., pressure gradients are neglected in this case  

Factor Bj is given by Eq. 7.128. The power consumption in the melt film can now be expressed as  

From Eqs. 7.176 and 7.177, it can be seen clearly that the power consumption in the melt film reduces with increasing clearance. 

The power consumption in the melt pool will be relatively small compared to the other two terms. Because of the relatively complicated flow pattern in the melt pool, the derivation of the power consumption for a power law fluid will be rather involved. To simplify matters considerably, the power consumption in the melt pool can be approximated with the power consumption in a screw channel of width W = W-W with a Newtonian fluid  

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The total mechanical power consumption in the melting zone now becomes ... 

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