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. Dy 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.