Meaning
Mathematical models determine the speed at which adjacent layers of a fluid move past each other during extrusion or pipe flow. A shear rate calculation determines the stress placed on a liquid by looking at the velocity gradient across the narrow opening of a die. It is a fundamental step in choosing the right pump and power settings for a production facility.
Fluid Dynamics
Calculating how hard a material is being squeezed helps predict changes in its viscosity. Through shear rate calculation, an engineer determines if the polymer will degrade under too much friction or if it will flow smoothly to fill a complex mold. This figure distinguishes the capability of a specific resin from its nominal capacity.
Engineering Setup
Sizing the holes in a die requires knowing how fast the material must move to meet cycle time targets. If the shear rate calculation produces a number too high for the molecular weight of the plastic, the final part will be weak. These numbers are used to build the operational recipes for every new item.
Process Stability
Consistent outputs rely on maintaining a steady flow through every cavity of a multi-gate tool. Differences in the values across the tool can cause warping or uneven density. Shear rate calculation ensures that every corner of the geometry receives the same material density during the shot.
