The plastic tea wax shell is produced by an injection molding machine. Injection molding machines typically provide 10,000 to 40,000 psi plastic pressure for filling packaging most parts, including thin walls. In many cases, the higher the pressure drop, the more difficult it is to form, any problems related to parts molds will be magnified. Any method that reduces the required pressure will improve the robustness of the process. Ideally, the pressure drop across the flow path to the component is small. However, most moldmakers only care about the runner system gate, even get a mold flow analysis to determine. Have you seen any filling research on nozzle design?

The first suggestion is to keep the nozzle body as short as possible to reduce pressure loss. This may be obvious, but I have seen nozzle lengths 50mm to 760mm everywhere. The 760 mm nozzle body requires more than 13,000 psi pressure to pass the plastic.

The flow path through the nozzle should be tapered instead of straight holes to provide a small pressure drop allow faster cleaning. Yes, the shape of the runner can help hinder the color resin conversion.

To be fair, if it is a long nozzle body, it is difficult to have a thick enough cone. In addition, the nozzle body may have a fusion filter mixing element, which also increases the pressure drop. These should evaluate the function pressure loss so that you know which filter is good provide a small pressure loss. In addition, if you look at the pressure loss, you can know when the filter needs to be replaced.