Runner injection molding is one of the key processes in plastics processing and molding, which injects molten plastic into the mold cavity through precisely designed runner and gate systems to form the desired product. This paper elaborates the basic principles, process characteristics, practical application cases and future development trends of runner injection molding, aiming to provide a clear and systematic understanding for non-professionals.
1. Introduction of runner injection molding
Injection molding is a widely used molding process in modern manufacturing industry, which has the advantages of high production efficiency, high automation and stable product quality. Runner injection molding as an important part of injection molding, whether its design is reasonable or not directly affects the quality of products and production costs.
2. The basic principle of runner injection molding
Runner injection molding is the process of injecting molten plastic from the injection molding machine nozzle into the mold cavity by using the runner and gate system in the mold. The runner system consists of three parts: the main runner, the manifold and the gate. The main runner connects the injection molding machine nozzle to the manifold, the manifold connects the main runner to the gate, and the gate is the channel that connects the manifold to the mold cavity.
3. Design of runner and gate
3.1 Runner design
Runner design should meet the good pressure transfer and maintain the ideal filling state, and in the flow process as small as possible pressure loss, can be balanced distribution of plastic melt to the various cavities. The manifolds are often designed with a trapezoidal cross-section for good processability and low heat dissipation and flow resistance of the plastic melt.
3.2 Gate Design
The design of gate directly affects the appearance, deformation, molding shrinkage and strength of injection molded products. According to the different characteristics of injection molded products, restrictive or non-restrictive gates can be used. Restrictive gates accelerate the flow rate of plastic melt by sudden change of cross-sectional area, increase the shear rate, and fill the cavity quickly and evenly.
4. Practical Example
Take cell phone shell as an example, use Moldflow software to determine the pouring position of the injection mold, and take the result of injection filling as the basis of design, use UG software to design the molding parts of the cell phone shell, lateral core extraction mechanism and cooling system. By optimizing the runner and gate design, the product design cycle was shortened and the development cost was reduced.
Data: The design cycle was shortened by 20% and the development cost was reduced by 15%.
5. Hot runner injection molding technology
Hot runner injection molding technology is to heat the runners and gates of traditional molds to keep the plastic at a certain temperature during the injection process, so as to improve the injection effect and production efficiency. Hot runner injection molding technology has the advantages of improving product quality, shortening molding cycle, saving raw materials and prolonging the service life of molds.
Data: Compared with the traditional cold runner injection molding, hot runner injection molding technology can save 20%-30% of raw materials and shorten the molding cycle by 30%-50%.
6. Future development trend
In the future, runner injection molding technology will pay more attention to the selection and compatibility of materials, and develop more efficient and reliable mold manufacturing technology. At the same time, hot runner injection molding technology will be combined with automated control and data analysis to improve the stability and controllability of the production process through real-time monitoring and adjustment of parameters such as temperature, pressure and injection speed.
7 Conclusion
Runner injection molding is one of the key processes in plastic processing and molding, and whether its design is reasonable or not directly affects the quality of the product and production costs. By optimizing the runner and gate design and adopting hot runner injection molding technology, the quality and production efficiency of products can be significantly improved. In the future, with the development of material science and automation technology, runner injection molding technology will usher in a broader development space.
