What is the working principle of the hot runner valve needle?

The principle of hot runner The hot runner system is composed of three parts: hot nozzle, runner plate, and temperature control box. It is a perfect glue feeding structure in plastic molding. The working principle of the hot runner system is to install a heater in the plastic mold, and use the principle of heating and temperature control to keep the runner of the mold in a molten state.
Hot runner mold is a mold that uses a heating device to keep the melt in the runner from solidifying.
Structure
The hot runner system is generally composed of several parts such as hot nozzle, manifold, temperature control box and accessories. Hot nozzles generally include two types: open hot nozzles and needle valve hot nozzles. Since the form of hot nozzles directly determines the selection of hot runner systems and the manufacture of molds, hot runner systems are often divided into open hot runner systems and needle valve hot runner systems accordingly. The manifold is used when there are multiple cavities in one mold or multiple feeding points, or when the material level is offset at a single point. The material is usually P20 or H13. Manifolds are generally divided into two categories: standard and non-standard. Their structural form is mainly determined by the distribution of cavities on the mold, nozzle arrangement and gate position. The temperature control box includes the host, cables, connectors and male and female wiring sockets, etc. Hot runner accessories usually include: heaters and thermocouples, runner seals, connectors and junction boxes, etc.
Advantages
1. Shorten the cycle
The molding cycle of the parts is shortened. Because there is no cooling time limit for the runner system, the parts can be ejected in time after molding and curing. The molding cycle of many thin-walled parts produced by hot runner molds can be less than 5 seconds.
2. Save plastic
In pure hot runner molds, there is no production waste because there is no cold runner.
3. Reduce waste
Reduce waste and improve product quality. During the hot runner mold molding process, the temperature of the plastic melt is accurately controlled in the runner system. The plastic can flow into each mold cavity in a more uniform state, resulting in parts of consistent quality. The gate quality of the parts molded by the hot runner is good, the residual stress is low after demolding, and the deformation of the parts is small. Therefore, many high-quality products on the market are produced by hot runner molds.
4. Production automation
Eliminating subsequent processes is conducive to production automation. The finished product is formed by the hot runner mold, and there is no need to trim the gate or recycle the cold runner. This is conducive to production automation.