Balanced Runner

For a molded part in a multi cavity mold to have a remote possibility of being the same the material should arrive at the gate in each cavity at the same time. As designers we were trained to use the geometrically balanced runner concept. This was achieved by making each path to the cavity the same distance from the nozzle to each cavity. This was thought to be the ultimate method for achieving perfect mold filling balance. Because we believed that consistent parts were desirable we forced this concept into our mold-quoting standard in mold making. We also quickly discovered that a balanced geometry could stay balanced if the cavity layout is mirrored. For example if a 2 cavity is balanced then a, 4 cavity is balanced and if a 4 cavity is balanced then an 8 cavity is balanced etc… for16, 32 and 64 and this is also why we quote molds in these cavitations. Then in some cases 3-cavity molds could be semi-balanced so we began quoting, 6,12,24, and 48 cavities.