According to the different casting system, the mold can be divided into: large nozzle mold, fine nozzle mold, hot runner mold. The hot runner mold is located in one or more hot runner plates with constant temperature and the hot runner mouth without cold material release on the products. Therefore, the hot runner does not need to be placed on the products. It is suitable for the products with expensive raw materials, high product requirements, difficult design and processing, and high cost of mold.
Hot runner system, also known as no water mouth system or hot runner system, mainly by hot runner sleeve, hot runner plate, temperature control electric box. The common hot runner system has two forms: single point hot runner and multi-point hot runner. A single hot gate is used to inject molten plastic directly into the mold cavity with a single hot gate sleeve. The multi-point hot gate is used to branch the molten material into each sub-hot gate sleeve and then into the mold cavity through the hot runner plate. It is suitable for single-cavity multi-point feeding or multi-cavity mold. What are the advantages of a hot runner system?
- Sorten the molding cycle. Without the limitation of the cooling time of the runner system, the parts can be pushed out in time after they are formed and solidified. Many thin wall parts produced with hot runner die molding cycle can be 5 seconds or less in the pure hot runner die because there is no cold runner, so no production costs. This is especially important for expensive applications of plastics. As a matter of fact, the major manufacturers of hot runner in the world developed rapidly in the era of high price of petroleum and plastic raw materials. Because the hot runner technology is an effective way to reduce the cost of materials.
- Reduce waste products and improve product quality. In the process of hot runner molding, the temperature of plastic melt is accurately controlled in the runner system. The plastic can flow more uniformly into the cavities, resulting in parts of the same quality. The quality of the parts gate formed by hot runner is good, the residual stress is low after demoulding, and the parts deformation is small. So many high quality products on the market are produced by hot runner mold. Many of the plastic parts in familiar MOTOROLA phones, HP printers and DELL laptops are made from hot runner molds。
- Low loss. The hot runner temperature is equal to the nozzle temperature of the injection molding machine, which avoids the surface condensation of the raw material in the runner and reduces the injection pressure loss. Eliminate the following process, which is beneficial to the production automation. The finished product is finished after the hot runner mold is formed, and there is no need to trim the sprue and recycle the cold runner and other processes. Facilitate production automation. Many foreign manufacturers combine hot runner and automation to improve production efficiency.
- Expanded the application of injection molding process. The reuse of nozzle material will degrade the performance of plastics, while the use of hot runner system without nozzle material can reduce the loss of raw materials, thus reducing the cost of products. The temperature and pressure are even in the mold cavity, the stress of the plastic parts is small and the density is even. For transparent parts, thin parts, large plastic parts or high demand plastic parts can show its advantages, and can produce larger products with smaller models. Many advanced plastic forming processes are developed on the basis of hot runner technology. For example, PET preforming, multicolor co-injection in the MOLD, multi-material co-injection process, STACK MOLD, etc.