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This defect occurs when the polymer shoots into the mold and does not create a smooth laminar, or fountain, flow as it first enters the mold cavity. A laminar flow occurs when the polymer enters the mold cavity from the center, spreads out to the edges of the mold surface to allow more material to enter through the center. In the case of jetting, the polymer streams into the mold cavity and shoots forward like a cylinder of polymer with the first polymer to enter the mold continuing towards the opposite wall rather than spread to the nearest wall. 

I was asked this question by a student the other day…

Runner technologies which balance the shear imbalance within the runner system and are invaluable in helping to minimize cavity imbalances. Tricks such as radii runner intersections might improve the imbalance, but I have seen enough proof to know that shear balancing is the most effective method of correcting for runner imbalance.

-Andy

There were many great advances to the programming and interface systems for robotics. Each advancement in simplifying the programming of robotics will improve the learning curve for a setup technician. One manufacturer even demonstrated the ability to have the robot mimic manual physical movements of the operator in real time.

With the extensive advances in the speed of robotics, there is a large amount of time that exists between the moment the robot removes the part from the mold and when it is needed again. At this NPE, there was a strong emphasis on multi-function robots which take advantage of their speed by performing multiple trimming, inspecting, and assembly tasks in between cycles. Molders who can take advantage of their robots capabilities between cycles will save time and money over the log time.

-Andy

One good way to check the consistency of the process is to routinely measure the part weight. A consistent part weight indicates the same amount of material is injected and packed each cycle. This wont necessary tell you what is wrong or has changed, but will be a good indicator of process shift.

-Andy