Text | Hot Runner Flow Path
From a literal perspective, the main difference between cold runner and hot runner systems lies in temperature control. A cold runner is the traditional form of injection molds. In this system, after the injection process, the material left in the flow channels solidifies and must be removed as waste. This material cannot be reused, leading to material wastage and increased production costs. While it has been widely used in injection molding, it is not the most efficient solution. To address these issues, hot runner technology was developed, aiming to reduce waste and improve efficiency. As a result, hot runner systems have gradually become the preferred choice in modern injection mold design and are expected to become more widespread in the future. However, due to cost considerations, many small and medium-sized molds still rely on cold runners. Some materials also require better control, making cold runners a necessary option in certain applications.
Today, both cold runner and hot runner technologies are commonly used in the injection molding industry. So, what exactly is a hot runner system?
A hot runner system uses heating elements to keep the plastic in the runner and gate areas molten throughout the injection process. Heaters are typically placed near or within the flow path, ensuring that the entire channel from the injection machine's nozzle to the gate remains at a high temperature. This means that after each cycle, the plastic in the flow path does not solidify, eliminating the need to remove and discard it. The system only needs to be heated to the required temperature before the next cycle. Because of this, hot runner systems are often referred to as "hot manifold systems" or "no runner molding."
What are the advantages of using a hot runner system?
- Saves raw materials and reduces overall costs
- Shortens the molding cycle, improving machine utilization
- Enhances the surface quality and mechanical properties of the final product
- Eliminates the need for three-plate molds by using point gates
- Enables economical production of single parts with side gates
- Increases automation levels in the production process
- Allows precise control of the gate through needle valve gates
- Ensures consistent quality across multiple cavities
- Improves the visual appearance of molded parts
However, like any technology, hot runner systems also come with some drawbacks:
- The mold structure is more complex, resulting in higher initial costs and maintenance expenses
- It may take time to stabilize the system during startup, leading to more defective parts
- If there is a melt leak or heater failure, it can significantly impact product quality and production schedules
With increasing resource scarcity, rising material costs, and growing market competition, saving materials has become more important than ever. This is one of the key reasons why hot runner technology has gained popularity. It is not just a trend, but an inevitable step in the advancement of industrial manufacturing.
Http://news.chinawj.com.cn Editor: (Hardware Business Network Information Center) http://news.chinawj.com.cn
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