3-DIMENSIONAL MODELING OF NON-NEWTONIAN FLUID-FLOW IN A COAT-HANGER DIE

The three-dimensional model of isothermal flow of power-law fluid in a coat-hanger die has been developed using finite element method. The s hape of coat-hanger die used in the present model was determined accor ding to the previous analytical design equation which is based on one- dimensional now model in the manifold and the slot. Because uniform fl ow rate across the die outlet is most important to achieve uniform thi ckness of extruded polymer sheet or film, flow rate distribution is ma inly examined to determine the valid process condition for the design equation as the design parameters are changed. The effects of fluid pr operty in terms of power-law index and process parameters not consider ed in one-dimensional design equation such as die inlet size and the p resence of land were analyzed. Results show that the manifold angle is the most influencing design parameter on flow rate distribution. When the material of different power-lau index from design value is proces sed, the change of power-law index affects the uniformity of now rate appreciably.