1. Differences in mold structure
In the molding of oversized plastic products, only the hot runner can be used to balance the plastic flow. For example, in the production of automotive interior linings, appliance housings and other components, more than the need to simultaneously enter the glue or chronologically into the glue, at this time, the hot runner is required to successfully complete this step. In addition, when the side feed is offset from the center of the injection molding machine, the hot runner feeding method can make the mold structure simple, and at the same time make the molding easier, speed up the molding speed, reduce the molding time, and produce no material.
Generally speaking, when the injection is performed by the three-plate method, the heavy master template needs to slide on the guide post, and even if the new mold is difficult to withstand the heavy load caused by the sliding for a long time, the life of the mold is not long. Further, in this manner, the amount of movement of the stencil to take out the flow material from the mold each time it is ejected is greater than the amount of stencil movement required to take out the molded product from the mold.
Therefore, hot runners are usually used when encountering the following conditions:
(1) It is necessary to use a long vertical flow path for the ejection of the side.
(2) In order to avoid problems caused by too long material heads.
(3) Forming some large products that allow eccentricity.
(4) In the use mode of the three-plate mold, the mother template needs to be moved to take out the material head. If the hot runner molding method is used, the mold opening motion can shorten the moving distance required to remove the material. Therefore, the three-plate mold method requires a large molding machine to produce a cold runner, and a small molding machine can be used after the hot runner is used.
(5) For materials with characteristics such as high viscosity, low viscosity or high molding temperature, the hot runner system can solve the problems of difficult molding. For example, in the processing of metal powder, ceramic powder, plastic magnet, plastic bearing and thermoplastic rubber injection molding.