I have received a few follow-up emails on venting, and would like to add the following comments and links for information…
Alternate Venting Techniques
Ejection – You should always consider venting your moving components such as ejector pins, ejector blades, lifters, stripper plates, and slides are all great components to vent. Since these move each cycle, they usually act as self-cleaning vents. Components such as vented ejector pins are already available commercially through many suppliers.
Porous Mold Steel – As long as you can vent to atmosphere, porous steels can be a great option for improving venting. These materials allow air to actually vent through the steel. For some design guidelines for such materials, please feel free to visit this helpful site:
Vacuum venting – To improve the efficiency of venting, many molders are turning to ‘negative cavity pressure’ techniques. These systems help draw the air out of the mold cavity faster allowing you to inject faster and maintain a more repeatable process. For a design guideline for vacuum venting, please feel free to visit this helful site: