Hot runner is a method of heating to ensure that the plastic in the runner and gate remains molten. The hot runner system generally consists of a hot nozzle, a temperature control box, a manifold and accessories. Thermal nozzles generally include two types: open thermal nozzles and needle valve thermal nozzles. The shape of the thermal nozzle directly determines the selection of the hot runner system and the manufacture of the mold. Today, hot runner manufacturers have sorted out some of the advantages of hot runner systems.
1. Saving raw materials and reducing product costs are the salient features of hot runner system molds. In the ordinary pouring system, a large number of forehearths are produced. When small products are produced, the weight of the runners of the pouring system may exceed the weight of the product. Since the plastic is always in a molten state in the hot runner mold, the product does not need to trim the gate, basically no waste processing, which can save a lot of raw materials. Because there is no need for waste recycling, material selection, crushing, dyeing and other processes, it saves time, labor and energy. The injection material is no longer mixed with the recycled gate material, so the product quality can be significantly improved. At the same time, because the plastic in the pouring system remains molten, the pressure loss during the flow is small, so it is easy to realize low-pressure injection molding of multi-gate, multi-cavity molds and large products. The hot gate is conducive to pressure transmission, and to a certain extent, it can overcome the defects of plastic parts such as depression, shrinkage, and deformation due to insufficient filling.
2. A wide range of applicable resins and convenient setting of molding conditions. Due to the improvement and development of hot runner temperature control system technology, hot runners are now used not only for polyethylene and polypropylene with a wide melting temperature, but also for heat-sensitive plastics with a narrow temperature range, such as polyvinyl chloride, Polyoxymethylene and so on. For polyamide (PA), which is easy to drool, you can also select a valve-type hot nozzle to form a hot runner system.
3. Simplified operation and shortened molding cycle are also important features of hot runner molds. Compared with ordinary runners, it shortens the mold opening and closing stroke, which not only shortens the demolding and molding cycle of the part, but also facilitates the realization of automated production.