What is a hot runner

1. What is a hot runner?

The hot runner uses heating to ensure that the plastic in the runner and gate remains in a molten state. Since there are heating rods and heating rings near or in the center of the runner, the entire runner from the barrel exit of the injection molding machine to the gate is in a molten state. The high-temperature state keeps the plastic in the runner molten. After shutdown, there is generally no need to open the runner to take out the condensate. When the machine is restarted, it is only necessary to heat the runner to the required temperature. In short, the hot runner is an extension of the barrel of the injection molding machine.

2. Structure of hot runner system

Hot runner systems generally include two types: open hot runner and needle valve hot runner.
Open hot runner generally consists of injection nozzle, manifold, hot nozzle, temperature control box and accessories.
Needle valve hot runner generally consists of injection nozzle, manifold, hot nozzle, temperature control box, cylinder or oil cylinder, valve needle, and accessories.
The mouth form of the hot runner is divided into large mouth and pointed mouth.

The manifold is used when a mold has multiple cavities or multi-point feeding, or single-point eccentric feeding. The size of the manifold is mainly determined by the distribution of the cavity on the mold, the nozzle arrangement and the gate position.

The temperature control box includes a host, cables, connectors, male and female wiring sockets, etc. Hot runner accessories usually include: heaters and thermocouples, runner seals, connectors and junction boxes, etc. Mainly to control the temperature of the manifold and hot nozzle.