1.integrated mainstream channel, this is the mainstream form one of the most simple, is in the fixed template by the overall composition and processing, the processing of the most simple, more suitable for simple die; combined sprue, if the fixed mould is composed of two pieces of the template, the sprue also can be processed separately in the two block the template, and then combined them together, the form is simple, but to ensure the coaxiality; bush type sprue sprue structure, which is the most commonly used, is the gate of inlay in the template, is applicable to all the plastic injection mold, this form, easy processing, detachment and heat treatment.
  2.Key points in the design of the main channel, in order to facilitate the aggregate out from the main channel gating system, sprue design into a cone, the cone angle of 2 degrees -4 degrees, the melt fluidity, cone angle is 3 degrees -6 degrees; the sprue tip rounded, usually take r as the radius 1-3mm, to reduce the melt the oversteer resistance; the sprue length should be as short as possible, otherwise it will make the aggregate mainstream channel increased, the pressure loss increase, excessive melt cooling and shaping, the sprue length should be less than 60mm; in order to make the molten plastic from the nozzle is completely into the main channel without overflow, should make the nozzle sprue and injection molding machine, butt joint, the joint often designed hemispherical pits, the radius slightly larger than the tip radius; surface sprue should try to smooth processing, avoid leaving effects of plastic flow and release the sharp burr; for liquid plastic, such as PE, the sprue size can be smaller, and the fluidity of plastics, such as PC, PS etc., the sprue size should be larger; as the sprue to contact and collision repeatedly with the nozzle, so the main channel part should give priority to the bush type, in order to choose Use high-quality steel processing and heat treatment.