Determining Cavitation Count and Cycle Time in Multi Cavity Injection Molds
Determining cavitation count and cycle time requires balancing thermal cooling physics against clamping limits, runner shear, and capital amortisation curves.
Shot Capacity Utilization
Meaning
Efficiency metrics comparing the total weight of the part and runner to the maximum capacity of the injection cylinder help prevent material degradation. Maintaining a proper shot capacity utilization ensures that the resin does not spend too much or too little time in the heated barrel. This balance is critical for protecting the physical properties of the polymer.
Residence Time
Low values of shot capacity utilization mean the material stays in the barrel for many cycles, which can lead to thermal breakdown. High residence time results in discolored parts, brittle structures and reduced mechanical strength. Moulders aim to stay between twenty and eighty percent of the machine limit to avoid these issues.
Dosage Precision
Operating at the very bottom of the cylinder range makes it difficult to control the shot volume accurately. Poor shot capacity utilization can cause variations in part weight because the screw cannot maintain a consistent cushion. This lack of control leads to dimensional instability across a production run.
Thermal Stability
Every resin has a specific window of time it can withstand high temperatures before its molecular chains begin to snap. Proper shot capacity utilization ensures that the material moves through the system at a rate that preserves its integrity.