The runner system should be designed in such a way that all of the parts finish filling at the same time. This can be achieved by balancing the runner system.
Before the design of runners for a family mold, analyze each part on its own. Once we know that each cavity is filling properly, the runner system can then be designed and created for a balanced fill path in each cavity.
If the runners are not balanced, molding problems such as hesitation, underflow and over packing may occur.