Hot runner molds can be divided into open hot runner molds and needle valve hot runner molds.

Due to the fact that the open hot runner breaks through the condensation gate when injecting glue with the screw of the injection machine forward, it can only be injected into the mold. Conversely, when the screw in the injection machine retreats, it can only be condensed with the gate to close the glue outlet. So usually, the choice of gate size is quite important. Otherwise, due to the temperature of the gate area, either the hot nozzle cannot eject glue due to condensation blockage, or there is wire drawing and salivation at the gate of the hot nozzle. If the gate cannot condense at the same time when the screw retracts, it will form a back suction force on the mold cavity, which is not conducive to maintaining pressure in the cavity.Commonly used are a bit gate hot runner, a straight gate hot runner, and a sub gate hot runner with sub runners.becauseThe open hot runner has a simple structure, simple mold processing, and low maintenance costs,In addition, the appearance requirements for injection products are not too high or procurement costs are considered. After use, there are also no or very few nozzle nozzles, so there are still many users using this type of hot runner. Commonly used are a bit gate hot runner, a straight gate hot runner, and a sub gate hot runner with sub runners.

And needle valve hot runner, the gate of the hot nozzle during multi hot nozzle injection in the first mock examinationWhen injecting glue with the screw of the injection machine,By gas (liquid) pressureCan be sorted in orderThe sequential adjustment valve needle opens the gate and injects glue, which can adjust the appearance of the product to address issues such as water lines, shrinkage, and warping.On the contrary, when the screw in the injection machine retreats,By means of gas (liquid) pressure, it can be arranged in sequenceSequentially adjust the valve needle to seal the gate without spraying glue. This sequential control can also compensate for the uneven filling of the mold cavity when multiple hot nozzles are simultaneously spraying glue. In addition, the needle valve hot runner gate is made slightly larger to reduce the shear heat of the glue outlet. By instantly opening and closing the glue outlet, the mold cavity is filled quickly, with good pressure retention, and no wire drawing or salivation. Only by using needle valve hot runners can it be used for injection molding of laminated cavity molds and multi cavity family products.Needle valve hot runnerThe structure is relatively complex, and the precision and maintenance of mold processing are relatively high. Although users consider procurement costs, it has many advantages and is also adopted by most users.

The needle valve hot runner is divided into three types: cylinder type needle valve hot runner, cylinder type needle valve hot runner, and spring type needle valve hot runner.Cylinder type needle valve hot runnerDue to the use of air pressure to push the valve needle open or closedThe mode of completing the injection of glue through the gate is convenient to use because there is ready-made compressed air in the injection workshop, and the connecting pipe is directly fed into the hot runner cylinder. However, the air pressure is limited and is also used by a large number of users.Oil cylinder needle valve hot runnerDue to the use of hydraulic pressure to push the valve needle open or closedThe mode of completing the injection of glue at the gate requires an oil pressure pipe to be input into the hot runner oil cylinder. This method is commonly used for injection molding of plastic parts with large surface area and wall thickness due to the high hydraulic pressure.Spring type needle valve hot runnerAdopting locking spring compression methodPush the valve needle to open or closeThe mode of completing the injection of glue through the gate has relatively small pressure adjustment, butEasy to use, with fewer users.