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Flaring dies to suppress die drool
Author(s) -
Ding Fan,
Zhao Lian,
Giacomin A. Jeffrey,
Gander Jesse D.
Publication year - 2000
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.11344
Subject(s) - die (integrated circuit) , materials science , extrusion , viscoelasticity , stress (linguistics) , structural engineering , shear stress , composite material , engineering , philosophy , linguistics , nanotechnology
Die lip build‐up is the unwanted material accumulation on extrusion die lips. Here, flared dies are shown experimentally to suppress die lip build‐up. A semiempirical method for flared die design is also provided. Nonlinear viscoelastic constitutive equations are used to calculate the wall shear stress and first normal stress difference in flared dies. By incorporating melt memory, a promising design method for die flaring is presented. The stress history upstream of the die exit governs the die design. The upstream gap is selected to maximize undershoot of the first normal stress difference N 1 at the die wall caused by flaring. The flare length, on the other hand, is selected to ensure a steady N 1 at the die lips.