The Difference Between Hot Runner Molds and Traditional Molds
What is a Hot Runner?
A hot runner uses heat to keep the plastic in the runner and gate molten. A hot runner system generally consists of a hot nozzle, a manifold, a temperature control box, and accessories. Hot nozzles generally come in two types: open hot nozzles and valve-type hot nozzles. Since the type of hot nozzle directly determines the choice of hot runner system and mold manufacturing, hot runner systems are often categorized accordingly.
The widespread use of hot runners stems from their unmatched advantages over traditional molds:
- Shortened molding cycle. Without the cooling time constraints of the runner system, parts can be ejected immediately after solidification. Many thin-walled parts produced with hot runner molds can achieve a molding cycle of less than 5 seconds.
- Conservation of plastic raw materials. Pure hot runner molds lack cold runners, resulting in no production costs. This is particularly significant in reducing raw material costs. In fact, major international hot runner manufacturers experienced rapid growth during an era of high oil and plastic raw material prices. Hot runner technology is an effective way to reduce material costs.
- Reduce waste and improve product quality. During the hot runner molding process, the plastic melt temperature is precisely controlled within the runner system. This allows the plastic to flow more uniformly into each mold cavity, resulting in consistent parts. Furthermore, hot runner-molded parts have superior gate quality, low residual stress after demolding, and minimal part deformation. Therefore, many high-quality products on the market are produced using hot runner molds.
- Eliminate subsequent processes, facilitating production automation. Parts molded in hot runner molds are finished products, eliminating the need for gate trimming and cold runner recycling. This facilitates production automation.
- Expand the application scope of injection molding. Many advanced plastic molding processes have been developed based on hot runner technology.