What is hot runner and the application of hot runner

Hot runner systems utilize heating methods to ensure that the plastic in the runner and gate remains in a molten state. Due to the presence of heating rods and heating coils near or in the center of the runner, the entire runner, from the nozzle outlet of the injection molding machine to the gate, is maintained at a high temperature, keeping the plastic in the runner molten. Generally, there is no need to open the runner to remove solidified plastic after shutdown, and when restarting, only the runner needs to be heated to the required temperature. Therefore, hot runner technology is sometimes referred to as a hot manifold system or no-runner molding.

What is a Hot Runner?

A hot runner is an extension of the injection molding machine's barrel that maintains the plastic in the runner and gate in a molten state through heating. With heating rods and heating coils placed near or in the center of the runner, the entire runner, from the barrel outlet to the gate, remains at a high temperature, ensuring the plastic in the runner stays molten. After shutdown, there is generally no need to open the runner to remove solidified plastic, and when restarting, only the runner needs to be heated to the required temperature. In short, a hot runner is an extension of the injection molding machine's barrel.

Structure of Hot Runner Systems

Hot runner systems generally include two types: open hot runner systems and valve-gate hot runner systems.

• Open Hot Runner Systems: Typically consist of a nozzle, manifold, hot tip, temperature control box, and accessories.
• Valve-Gate Hot Runner Systems: Typically consist of a nozzle, manifold, hot tip, temperature control box, cylinder (either pneumatic or hydraulic), valve pin, and accessories.

The nozzles of hot runner systems come in two forms: large gate and fine gate.

• Manifold: Used in multi-cavity molds or when multiple feed points or single eccentric feed points are required. The size of the manifold is primarily determined by the distribution of the cavities on the mold, the arrangement of the nozzles, and the position of the gates.