After answering some follow-up questions from the last post, I decided to clarify the difference between Dynamic cavity balancing and Static cavity balancing with repsect to either injeciton molding or injection-blow molding.
Dynamic Cavity Balancing
When the mold cavity is filling, the polymer flow front is considered dynamic, or in motion. The balance of two or more mold cavities at this stage primarily relates to the consistency of pressure loss and shear balancing between the mold cavities. This relates to both hot and cold runner systems. The more the cavities are dynamically balanced, the more consistent the process will be in the long term.
Static Cavity Balancing
Once the flow front reaches the end of the mold cavity, it becomes static. At this stage, part weight differentials are primarily based on the variability in pressures and temperatures. This information is important for final part quality, but can be significantly different than the dynamic balance.