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Design of extruder dies using thermoplastics melt properties data
Author(s) -
Powell P. C.
Publication year - 1974
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760140410
Subject(s) - die (integrated circuit) , materials science , composite material , ultimate tensile strength , shear rate , conical surface , plastics extrusion , wedge (geometry) , volumetric flow rate , die swell , extrusion , viscosity , mechanics , geometry , mathematics , nanotechnology , physics
The procedures developed in this paper enable the die designer to estimate the dimensions of the die at the exit and to define a flow channel within the body of the die appropriate to the required dimensions and output rate of the extruded product. Design procedures are given for predicting die swell (and hence die exit dimensions) from a knowledge of product dimensions, output rate and the basic shear, elasticity, and viscosity data. Within the body of the die the length and included angle of a convergent tapered section should be such that the critical tensile deformation rate is not exceeded. At the die entry the taper angle is related to the tensile and shear viscosities. Analytical expressions based on flow data are given for predicting pressure drops resulting from flow through circular and slot dies of constant cross‐section and through conical and wedge‐shaped dies. A numerical example shows how the theory may be applied to the design of a die for a thin‐walled tube. For the resultant die design, the likely effects are predicted to changes in output rate and melt temperature for the chosen material, of changes in grade of the same type of polymer, and of changes in polymer type.