Hot runner injection mold is also called runnerless injection mold. The difference between its pouring system and ordinary pouring system is that during the entire production process, the plastic in the pouring system is always in a molten state, and the pressure loss during injection is small, and it can be used for multiple points. Pouring, multi-cavity molds and large plastic parts can achieve low-pressure injection molding. In addition, this pouring system has no pouring system condensate, realizing waste-free processing, eliminating the process of removing the gate, and saving manpower and material resources.
Due to the special process of the hot runner in the molding process, this type of injection molding method has the following characteristics.
① Save materials, energy and labor. The condensate of the gating system of ordinary injection molded parts accounts for a large proportion of the material consumption. The problem is that it is easy to bring in foreign matter and cause pollution, which reduces the performance of the secondary molded plastic parts. The material in the flow channel of the thermosetting plastic will completely become waste after solidification. Cannot be reused.
There are no such runner aggregates in the hot runner injection mold. For thermosetting plastics, this part of the plastic consumes less; for thermally explicit plastics, the recycling of these aggregates is eliminated, and the long-term production energy saving is quite big.
②Improve the quality of plastic parts. In the hot runner mold, the plastic in the runner is always in a molten state, which reduces the melt flow and facilitates the transfer of pressure to the cavity: it can make the pressure distribution in the cavity more uniform. Reduce the temperature difference of the melt; avoid or improve the welding line; can shorten the holding time, reduce the stress of the filling material, and reduce the gate marks to the minimum. In short, the internal and appearance quality of plastic parts can be improved.
③ Shorten the molding cycle. The plastic injection molding cycle includes mold closing time, mold filling time, refill time, cooling and solidification time, and demolding time. Using hot runner molds, these periods of time can be shortened. There is no runner aggregate and no need to use a three-plate mold (even with a point gate), so that the required opening and closing strokes are reduced. The runner melt is always kept molten, which makes it easy to carry out the pressure holding and refilling. For thicker plastic parts, a smaller gate than the general runner can be used to shorten the cooling time. The long-term production of large quantities and the reduction of man-hours brought about by the shortened molding cycle are considerable.
④ Material saving, energy saving and labor saving. Generally speaking, the mold cost of the hot runner mold increases by about 10% to 20%, but this increase can be quickly compensated by the above-mentioned economic benefits. However, the structure of the hot runner injection mold is very complicated; especially the temperature control requirements are strict, otherwise the plastic will be easily decomposed and scorched, and the manufacturing cost is high, which is not suitable for small batch production.
Post time: Nov-24-2021