First, the cold runner: refers to the part between the mold entrance and the product gate. Plastic in the flow channel by injection pressure and its own heat to maintain the flow state, flow channel as a part of the molding material, but not part of the product. Therefore, when we design the mold, we should not only consider the filling effect, but also consider how to save the material by shortening and narrowing the flow path. This is ideal, but in practical applications, it is difficult to achieve the best of both worlds.
Second, the hot runner: As a common part of the injection mold system, through the heating method to ensure that the runner and gate plastic to maintain the molten state. Because of the heating rod and heating ring in the vicinity of the flow channel or in the center, the entire flow channel from the nozzle of the injection molding machine to the gate is in a high temperature state, so that the plastic in the flow channel remains melted. After shut down, it is generally not necessary to open the flow channel to remove the condensate Material, then just turn on the heating runner to the desired temperature. Thus, hot runner processes are sometimes referred to as hot header systems, or run-less molding.