The gating system is one of the most important issues i […]
The gating system is one of the most important issues in the design of injection molds. The gating system is a complete transport channel that guides the plastic melt from the injection machine nozzle to the mold cavity. It has the functions of mass transfer, pressure holding and heat transfer. It has a decisive influence on the quality of plastic parts. Whether its design is reasonable, affects the overall structure of the mold and the ease of its operation.
The function of the gating system is to smoothly fill the plastic melt into the depth of the cavity to obtain a plastic product with a clear outline and excellent internal quality. Therefore, in the filling process, it is required to be fast and orderly, the pressure loss is small, the heat loss is small, the exhausting condition is good, and the pouring system is easy to separate or cut from the product.
Ordinary runner casting system
Ordinary runner systems, also known as sprue systems, or gating systems, are the necessary passages for molten plastic from the injector nozzle to the cavity. The runner system includes a main runner, a runner, a gate, and the like.
The main channel is a section of the channel connecting the nozzle of the machine to the entrance of the branching channel, which is the first place where plastic enters the cavity of the mold. It can be understood as a flow passage of molten plastic starting from the nozzle of the injection molding machine to the bypass.
Its size and size are closely related to the plastic flow rate and the filling time. Too much causes too much recycled cold material, the cooling time increases, and the occluded air increases. It is easy to cause bubbles and loose tissues, and it is easy to generate overcurrent and insufficient cooling;
If the flow path is too small, the heat loss is increased, the fluidity is lowered, and the injection pressure is increased, resulting in difficulty in molding. In general, the main runners are made into separate sprue sleeves that are placed on the parent template. However, there are some exceptions. Some small molds, because the requirements are not so high, can be used to open the main channel directly on the mother template without using a sprue bush.