The gating system refers to the part of the flow path before the plastic enters the cavity from the nozzle, including the main channel, the cold material hole, the runner and the gate.
The gating system, also known as the runner system, is a set of feed channels that direct the plastic melt from the nozzle of the injector to the cavity, typically consisting of a main flow channel, a runner, a gate, and a cold pocket. It is directly related to the molding quality and production efficiency of plastic products.
It is a section of the mold that connects the injection nozzle of the injection molding machine to the runner or cavity. The top of the main flow channel is concave for engagement with the nozzle. The main channel inlet diameter should be slightly larger than the nozzle diameter (0.8mm) to avoid spiking and prevent the two from being blocked due to inaccurate convergence. The diameter of the inlet depends on the size of the product, usually 4-8mm. The diameter of the main flow path should be enlarged inwards at an angle of 3° to 5° to facilitate the stripping of runners.
Cold material hole
It is a hole located at the end of the main channel to trap the cold material produced between the two shots at the tip of the nozzle, thereby preventing the clogging of the runner or the gate. If the cold material is mixed into the cavity, the internal stress is easily generated in the manufactured product. The cold material hole has a diameter of about 8-10mm and a depth of 6mm. In order to facilitate demoulding, the bottom is often borne by the stripper. The top of the stripping rod should be designed as a zigzag hook or a depressed groove so that the strip can be smoothly pulled out during demoulding.