Meaning
Simultaneous forming of multiple identical or family parts within a single tool frame maximizes production output per press cycle. Practice of multicavity injection molding relies on balanced runner systems and uniform cooling layouts to deliver identical melt volume and pressure to every cavity impression. Process stability breaks down when thermal gradients across mold plates or flow imbalances cause cavity-to-cavity dimensional variations.
Resin datasheets specify material properties derived from single cavity specimens, which do not reflect the statistical spread in dimensions across a multi-impression production tool. Packaging and medical high volume operations utilize tools with up to one hundred twenty eight cavities to achieve low unit costs.
Runner Balancing
Geometrically balanced runner networks equalize flow path lengths and pressure drops from the main sprue to every gate location. Melt flippers alter shear histories inside branch runners to prevent inner cavities from filling faster than outer impressions.
Production Efficiency
Spreading machine hourly operating costs across numerous parts per cycle drastically lowers individual component manufacturing costs. Fast cycling multicavity tools increase total annual production volume without requiring additional injection moulding presses.
Cavity Imbalance
Temperature differences between inner core blocks and outer frame plates create localized viscosity shifts that alter cavity filling rates. Flash on overfilled cavities and short shots on underfilled impressions signal unacceptable runner system imbalance.
