Needle Valve Hot Runner vs. Open Hot Runner
Needle valve hot runners and open hot runners are two common types of hot runner systems. They differ in several key aspects:
1. Structure
Needle valve hot runners use a needle valve mechanism to control the flow of molten plastic. The opening and closing of the needle valve are controlled by both injection pressure and spring force.
Open hot runners do not have a needle valve mechanism. The flow of molten plastic is controlled directly by injection pressure.
2. Working Principle
In needle valve hot runners, under injection pressure, the needle valve opens and the molten plastic flows out. When the injection pressure decreases, the needle valve closes and the molten plastic stops flowing.
In open hot runners, under injection pressure, the molten plastic flows out directly. When the injection pressure decreases, the molten plastic solidifies and blocks the sprue, stopping the flow.
3. Advantages
Open Hot Runners
Large injection volume: Open hot runners have a large injection volume, which can improve the filling efficiency of the mold and reduce the injection cycle time.
Simple structure: Open hot runners have a simple structure, which is easy to install and maintain.
Convenient installation: Open hot runners are easy to install, which can save time and labor costs.
Wide range of applications: Open hot runners can be used for a wide range of products, including those with low appearance requirements, side-gated products, and molds.
Needle Valve Hot Runners
Precise process control: Needle valve hot runners provide more precise process control, which can be used to optimize the injection molding process.
Automatic closure after injection: Needle valve hot runners automatically close after injection, which can prevent material leakage and drooling.
Variety of options: Needle valve hot runner systems are available in a variety of options, including single-point needle valves, multi-point needle valves, gas-sealed needle valves, hydraulic needle valves, and sequence needle valves.
