The role of hot runner in plastic molds

Hot runner is also called hot water nozzle, which turns the solidified nozzle into a molten nozzle. Its composition is relatively simple, mainly including manifold, hot nozzle, thermostat, etc. Among them, the manifold can be divided into I-shaped, X-shaped, Y-shaped, T-shaped, mouth-shaped and other special shapes according to shape; the hot nozzle can be divided into large nozzle, sharp nozzle, needle valve nozzle according to shape; the thermostat can be divided into core type, plug-in type and computer centralized control type according to the temperature control method.

In injection molding, hot runner is used in conjunction with mold and plays a very important role. For example, in the injection molding production of ultra-thin parts (such as mobile phone battery cover), high-precision and high-quality products can be easily produced by using hot runner; for injection molding materials with poor fluidity (such as LCP), the use of hot runner can significantly improve the fluidity of the raw materials and ensure the smooth progress of injection molding production; for some large injection molding parts, such as automobile bumpers and door panels, TV back shells, air conditioner shells, etc., by using hot runners, very difficult injection molding becomes relatively simple.

In multi-cavity mold injection molding, molding is impossible without hot runners. It can be said that hot runners are the best technology to ensure runner balance. Because plastic has shear force in the runner, no matter how reasonable the geometric balance of the mold is, the weight of the molded product is difficult to be consistent, especially for multi-cavity molds. If hot runners are not used, the outside of the molded product will be lighter than the inside.

For plastic processors, as long as there is a certain batch of injection molding production, it is quite economical to use hot runners. This is because hot runners help companies eliminate sprues in injection molding production. In most cases, sprues cannot be reused. Sometimes, the weight of the sprue is almost the same as the weight of the product. If traditional sprue injection molding is used, it means that the amount of raw materials wasted is the same as the raw materials used in the product. Based on this calculation, the use of hot runners can save 30% to 50% of raw materials. In addition, hot runners can also help reduce mold wear and extend the life of the mold. Generally speaking, the service life of hot runner molds is twice that of fine sprue molds.