Hot runner is a circulating injection molding production used to help plastic melt on the mold, it can also control our material temperature, consistency and injection pressure, etc., so that the technician can do as he likes when adjusting the machine, has reached the ideal product, because the hot runner is in a high temperature environment for a long time, it will inevitably encounter some abnormal temperature, glue filling and other problems. This is also all hot runner is unavoidable, and to deal with these problems need professionals to complete, in the many hot runner manufacturers which manufacturers can do strong after-sales service? What causes hot runner leakage?
In most cases, the leakage of the hot runner system is not caused by poor planning, but because it is not operated in accordance with the planning parameters. Generally, the leakage occurs at the seal between the hot nozzle and the diverter plate. According to the general hot runner planning specifications, there is a steel edge at the hot nozzle, which can ensure that the height of the hot nozzle assembly is less than the practical groove depth on the hot runner plate. The reason for planning this difference between scales (commonly referred to as the cold gap) is to avoid damage to the components due to thermal expansion when the system is at operating temperature. For example, for a 60mm thick shunt plate and a 40mm hot nozzle assembly (total height is 100mm), when the temperature rises to the operating temperature of 230 ° C, it will generally expand by 0.26mm. If there is no cold gap, thermal expansion will often form the edge of the hot nozzle damage. Therefore, no effective seal under cooling conditions is the main reason for the formation of hot runner leakage in general, in order to ensure the sealing of the system (hot nozzle and shunt plate), it is necessary to heat the system to the operating temperature, so that the force generated is enough to offset the injection pressure, and then avoid the injection pressure to open the two parts. In general, inexperienced operators often do not wait for the system to reach operating temperature, and worse, they may even forget to turn on the heating system. In this way, the pressure on the surface of the hot runner with a cold gap cannot avoid material leakage before it reaches its operating temperature.
In addition, in the case of excessive heating may also occur leakage phenomenon. Because of the poor adaptability of the hot nozzle with a rigid edge to thermal expansion, when the system is over-heated, once it is lowered to the operating temperature, the sealing pressure can not avoid leakage due to the influence of the steel deformation. In this case, in addition to the system damage caused by the leakage of material, the hot nozzle will be irrecoverable damage due to excessive pressure, and then the hot nozzle needs to be replaced. Because the preload of the hot nozzle and diverter plate is very important, it is necessary to strictly comply with the scale and service requirements provided by the hot runner supplier to effectively avoid system leakage. Therefore, the mold manufacturer should carefully check the height of all the hot nozzle components and the size of the groove according to the drawing requirements of the hot runner supplier, and if there is a problem, it should also communicate with the hot runner supplier in time.