Customers may not be very careful about the use of hot runner system. Today, Sok hot runner will tell you that we should pay special attention to the injection pressure when selecting hot runner system.
The injection pressure loss in the hot runner system can not be ignored. Many hot runner mold users have a misunderstanding: the plastic solution in the hot runner is always hot, so the injection pressure loss of the hot runner is much smaller than that of the cold runner.
In fact, in order to meet the needs of hot runner structure design, the flow distance of solution in the hot runner system will be greatly increased, so the injection pressure loss in the hot runner system can not be underestimated. In practical application, due to the excessive injection pressure loss in the hot runner system, there are many difficulties in injection molding. Therefore, CAE software should be used to analyze and calculate the runner for the processing of plastics with poor fluidity (such as PC, POM, etc.), the large flow distance of solution in the hot runner system, and the large weight of parts.
After the production of hot runner injection mold is completed, the shutdown steps similar to that of injection machine must be followed:
1、 Turn off the heater of the hot runner system.
2、 Then turn off the cooling system of the die. For the heated hot runner system, the cooling system of the die can be turned off only after the temperature drops to 80 ℃.
Before finishing the production of hot runner injection mold, the high-temperature plastic and heat sensitive plastic must be refueled and cleaned. For some plastics such as PC, they can stay in the hot runner system and the barrel of the injection machine. At low temperature of about 160 ℃, the injection can be interrupted for 12 hours, but it can not be interrupted for a long time. The injection of thermosensitive plastics cannot be interrupted. In the barrel of the injection machine and the channel of the hot channel, there is a strong adhesion between the cured or semi cured plastic and the metal surface, and even the nitride layer is separated. The screw of the injection machine and the pin of the switch nozzle have a surface nitriding layer. Therefore, do not interrupt the injection and perform melt cleaning before shutdown.