When your molder is bringing a new mold on-line, do they “go for it” first shot (filling the mold) or do they set up for intentional short shots ( 90%+) of the cavity?
Shooting a mold short, perhaps most importantly, allows for a determination of the viscosity curve and identifying an optimum fill rate. Knowing both how AND why to set your fill rate is maximizing the production cycle and making best use of the mold. If the injection pressures are unnecessarily high, the condition will be a problem multiplier for any other processing issues that may be present.
Another benefit of starting out short is not slamming the parting line right away. Excessive pressure can cause damage to the parting line and start down a path to flash. During the initial shots, even slight damage that is barely noticeable will begin to grow with each run and take you down that path.
Intentional short shots also give you feedback on the mold-flow used as a guide for designing the mold. Whether through software simulation, experience or a combination, the concept was just a concept. Learning early that the planned mold-flow was correct gets you to production faster.
So when your molder is sampling a new mold or a change, ask them if they came up short. The answer may tell you a bit about how they are handling the mold you just paid dearly for.