A number of factors should be considered when deciding how many cavities can be filled from a runner system.
The number of cavities which can be filled from any given runner system depends on the following:
Machine size (available clamp force)
Available shot volume
Available production time
Required product quantity
Shape and size of the moldings
The number of cavities filled from a particular runner system can affect the ease with which the program arrives at a runner balancing solution. The possible combinations of pressure drops in the runner system itself and in filling the cavity volumes can rapidly increase the complexity of the balancing problem.
Following are simple formulas for determining the number of cavities. Use the minimum value derived from these formulae.
Number of cavities =
- = 80% of machine capacity
- = part weight