Flaring dies to suppress die drool

Citation
F. Ding et al., Flaring dies to suppress die drool, POLYM ENG S, 40(10), 2000, pp. 2113-2123
Citations number
15
Categorie Soggetti
Material Science & Engineering
Journal title
POLYMER ENGINEERING AND SCIENCE
ISSN journal
00323888 → ACNP
Volume
40
Issue
10
Year of publication
2000
Pages
2113 - 2123
Database
ISI
SICI code
0032-3888(200010)40:10<2113:FDTSDD>2.0.ZU;2-G
Abstract
Die lip build-up is the unwanted material accumulation on extrusion die lip s. Here, flared dies are shown experimentally to suppress die lip build-up. A semiempirical method for flared die design is also provided. Nonlinear v iscoelastic constitutive equations are used to calculate the wall shear str ess and first normal stress difference in flared dies. Dy incorporating mel t memory, a promising design method for die flaring is presented. The stres s 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.