The shunt of melt into the mold shunting and steering function, multi impression moulds must set Branch, if the single cavity forming large plastic parts, such as the use of multi gate feeding, also need to set the shunt.
  1.Design principle shunt. Melt with heat and pressure loss of the shortest path, minimum, fast into the cavity; melt from the gate into the cavity temperature and pressure to ensure that products should be the same, the cavity of the shrinkage of the same; turning shunt should be based on the circular arc transition, and junction gate should be processed bevel, and melt flow; the injection pressure is sufficient, the runner section and the length of the value should be as small as possible.
  2.Section of the shunt. Section used a round, U shape, trapezoid, rectangular, linear, parabolic. In the select the section shape, should consider a few factors thermal efficiency, channel efficiency, processing difficulty. Melt flow in the passage, plastic condensation curing contact with the mold, has thermal insulation effect, melt flow only in the channel, therefore, the ideal state of the shunt should be the center line and the gate center line on the same straight line. Circular section runner can achieve this point, and it is easy to process, the most commonly used.
  3.The runner section size and length. The runner section size and the types of plastics, plastic parts wall thickness, shape, volume, the runner length is related to many factors such as. In general, the fluidity of plastics, such as PE, PP, when the shunt is very short, the section size is about 2mm; the fluidity of plastics, such as PC, PVC, PMMA, the shunt diameter is more than 12mm, the majority of plastic for the diameter of the shunt in between 6-10mm. The runner length depends on the mold cavity layout scheme and the gate location, the output from the melt to reduce the pressure loss and the heat loss, and reduce the condensed material requirements, should strive to shunt the length of the shortest. The runner length depends on the mold cavity layout scheme and the gate location, the output from the melt to reduce the pressure loss and the heat loss, and reduce the condensed material requirements, should strive to shunt the length of the shortest.
  4.The runner layout. Layout determined shunt in cavity layout, has balanced and non balanced two main layout. Balanced layout. This arrangement requires a major channel to each cavity shunt tract length, shape, size of cross section must be equal, so that each cavity to flow and heat balance and melt. Therefore, the size of the gates should be the same each cavity, the cavity can also balanced feed. Arrangement of form, mainly in the circular permutation and H shaped arrangement, arranged in a circular pattern effect is good, is also the most commonly used. The non balanced layout. The characteristics of this layout is from the runner sprue to each cavity length is not the same, in order to make each cavity can also balanced feed, the gate size must be different, find the demon after careful calculation.