Volume Curves: Shrinkage or Leakage?

In tip #178 you saw how the screw moves forward as a thick, semi-crystalline part continues to shrink after “packing”. The action of this shrinkage can be studied by making the volume curve scale larger to see the detail after the cavity pressures reach their...

When “Hold” Isn’t Hold in Decoupled III

Once upon a time a customer complained using Decoupled III “didn’t work.” After wiping some egg off of our faces we found out what he meant: That D3 did not control the part dimensions when viscosity varied. We can show that D3 does control the process in almost all...

The Molding World in Quadrants

We often risk using a kind of “one size fits all” mode of thinking about plastic processes, their control and quality monitoring. I have found the following diagram useful for separating the different regions in the world of injection molding.(For those who need the...

Why Use a Percent of Peak for Pack?

In order to calculate good pack numbers† from cavity pressure sensors, the eDART™ must be given the correct information about what “packed” means. In the Sequence Settings you select the sensor location you want to use to determine whether the cavity is packed. Why...

Full Integrals vs. Fill and Pack Integral

In Tip #174 you saw how Fill and Pack Integral could be useful for monitoring dimensions in very thin-wall, fast freezing parts. In that discussion we used End of Cavity as the indicator, assuming that the dimension near the end of the cavity was most important.A...

Wherefore “Fill and Pack Integral”?

We have recently seen several customers using the eDART™ summary value “Fill and Pack Integral” for a part quality alarm. This value and “Fill and Pack Time” are most used for thin-wall molding quality alarms. We do not recommend using these for modest aspect ratio or...