Computational simulations of glass extrusion are performed to quantify the effects of materials behaviour and slip at the die/glass interface on the die swell. Experimental dat for three glass types are used to guide the computational study, which considers glass mateiral to ve viscous with and without shear thinning and viscoelastic using the Maxwell upper-convected model. The study starts with assuming no slip at the glass/de swell results, and then considers slip using the Navier model where interface shear is directly proportional to the relative slip speed at the interface. Consistent with the possibility of slip and intended high viscosity applications, viscosity ranging from 107.4-108.8 Pa.s was used. Based on the optimisation of the various input parameters required to achieve the measured die swell and ram force values, the study concludes that interface slip occurred as only extreme values of the shear thinning parameters provided an alternative.
