During a runner balance calculation, runner dimensions are altered within, or as close as possible without affecting the balanced fill, any constraints set, to ensure that cavities fill at the same time and that the volume of the runner system is minimized.
Considerable savings in material usage can be made by creating a well balanced runner system.
You can only balance runner systems for single-gated parts.
When you create the original runner system, make the runner sizes too big. This will help the runner balance calculation arrive at a sensible solution.
It is important to ensure that you are satisfied with each of the following aspects from the Fill analysis before you run a runner balance:
Molding conditions.
Gate locations.
The aim is to achieve runner dimensions which:
Have the same pressure drop in all flow paths, so that all cavities fill at the same moment.
Minimize the volume of runner material, relative to cavity volume, by achieving the highest possible pressure drops in the runner system.
Generate controlled shear heating, to minimize stress levels without using a high melt temperature.