Method of measuring true shear viscosity profile of molding material in capillary and molding system performing the same

A method of measuring a true shear viscosity profile of a molding material in a capillary, comprising:

• measuring a setpoint temperature of the molding material before injecting into the capillary;
• measuring a temperature at a predetermined position in the capillary, wherein a distance between the predetermined position and an inlet of the capillary is about ⅓ of a longitudinal length of the capillary;
• obtaining an initial shear viscosity profile at the setpoint temperature with respect to a shear rate of the molding material;
• fitting an initial temperature profile with respect to the shear rate according to the initial shear viscosity based on a Cross William-Landel-Ferry (Cross-WLF) model;
• fitting a first shear viscosity profile and a first temperature profile with respect to the shear rate according to the initial temperature profile based on the Cross-WLF model, wherein the initial temperature profile is obtained according to the temperature at the predetermined position in the capillary;
• and
• setting the first shear viscosity profile as the true shear viscosity profile when a difference between the first temperature profile and the initial temperature profile is not greater than a predetermined threshold, wherein the predetermined threshold is about 0.1° C.