Hot runner molds are widely used in developed countries and regions in the world today. This is mainly because hot runner mold has following salient features:.

 

Because there is no restriction on cooling time of runner system, parts can be ejected in time after they are solidified. Many thin-walled parts produced with hot runner molds can have a molding cycle of less than 5 seconds. .

Since there is no cold runner in pure hot runner mold, there is no production waste. This is especially significant for applications where plastics are expensive. In fact, major hot runner manufacturers in the world have all developed rapidly in the era when petroleum and plastic raw materials were expensive in the world. Because hot runner technology is an effective way to reduce material costs. .

Hot runner molds have been successfully used to process various plastic materials. Such as PP, PE, PS, ABS, PBT, PA, PSU, PC, POM, LCP, PVC, PET, PMMA, PEI, ABS/PC, etc. Any plastic material that can be processed with cold runner molds can be processed with hot runner molds. .

The smallest part made with hot runner mold is less than 0.1g. The largest is more than 30 kilograms. Application is extremely wide and flexible. .

Hot runner molds are widely used in various industrial sectors such as electronics, automobiles, medical care, daily necessities, toys, packaging, construction, and office equipment. .
Production situation of hot runner molds in the world
Hot runner mold production is extremely active in countries and regions with more developed industries in the world. Proportion of hot runner molds continues to increase. Many small mold factories with less than 10 employees are engaged in production of hot runner molds. Generally speaking, North America and Europe have used hot runner technology for a long time, with more experience and higher level. In Asia, apart from Japan, Singapore, South Korea, Taiwan, and Hong Kong are in a leading position. In North America and Europe, although level of mold manufacturing is higher, price is higher and delivery time is longer. In contrast, Asian hot runner mold manufacturers are more competitive in terms of price and delivery time. Hot runner mold in China is still in its infancy, but it is growing rapidly and proportion is increasing.
While hot runner technology is getting hotter in our country, its components show several major development trends.

Components are miniaturized, which can realize multi-cavity for small products and multi-gate filling for large products. By reducing nozzle space, more cavities can be configured on the mold, product output and utilization rate of injection machine can be improved. This is very important for modern plastic processing industry where time is money. Nozzle developed by internationally renowned mold company MoldMaters for small parts includes an integral heater, needle tip and melt channel, with a volume diameter of less than 9 mm, a gate distance of only 10 mm, and a product with a molding quality of 1 to 30 grams. .

At present, users require shorter and shorter mold design and manufacturing cycles. Standardizing hot runner components will not only help reduce repetition of design work and reduce mold costs, but also facilitate replacement and maintenance of vulnerable parts. Nozzles, stems and manifolds of companies such as Husky, Presto, and MoldMaters are all standard, which facilitates quick replacement and delivery of molds. Now foreign countries can deliver molds in only four weeks. .

Nowadays, major mold companies at home and abroad attach great importance to design of hot runner plate, research and development of pressure distribution, temperature distribution, and sealing of hot nozzle connection part. Development and utilization of laminated hot runner injection molds is also a hot spot. Stacked molds can effectively increase number of cavities, while requirements for clamping force of injection machine only need to increase by 10% to 15%. Stacked hot runner molds have been industrialized in some developed countries abroad. .

In hot runner mold molding, development of a more precise temperature control device to control temperature of molten resin in hot runner plate and gate is an effective measure to prevent resin from overheating degradation and product performance degradation. Luo Baihui believes that wide application of hot runner technology is a major change in plastic molds. In terms of injection molding, it has many unparalleled advantages. With further maturity of technology and reduction of manufacturing costs, hot runner technology will increasingly show huge advantages. In recent years, world-renowned hot runner technology suppliers have entered Chinese market one after another in various ways, which shows huge development potential of Chinese hot runner mold market. .
During molding process of hot runner mold, temperature of plastic melt is accurately controlled in runner system. Plastic can flow into each cavity in a more uniform state, resulting in parts with consistent quality. Gate quality of parts formed by hot runner is good, residual stress after demolding is low, and deformation of parts is small. Therefore, many high-quality products on the market are produced by hot runner molds. For example, many plastic parts in familiar MOTOROLA mobile phones, HP printers, and DELL laptops are made with hot runner molds. .

After parts are formed by hot runner mold, they are finished products, and there is no need to trim gates, recover cold runners, which is conducive to production automation. Many foreign product manufacturers combine hot runners with automation to greatly improve production efficiency.

Many advanced plastic molding processes are developed on the basis of hot runner technology. Such as PET pre-molding production, multi-color co-injection in mold, multi-material co-injection process, STACKMOLD, etc. .
Although compared with cold runner molds, hot runner molds have many significant advantages, mold users also need to understand shortcomings of hot runner molds. In summary, there are following points.

Hot runner components are more expensive, and cost of hot runner molds may increase substantially. If output of parts is small, proportion of mold tool cost is high, which is not economically expensive. For many mold users in developing countries, high price of hot runner systems is one of main problems that affect widespread use of hot runner molds. .

Hot runner molds require precision machining machinery as a guarantee. Integration and cooperation requirements of hot runner system and mold are extremely strict, otherwise there will be many serious problems in mold production process. For example, poor plastic sealing leads to plastic overflow and damage to hot runner components to interrupt production, poor relative position of nozzle insert and gate leads to a serious decline in product quality. .

Hot runner mold has a wide range of applications. At the same time, this trend is also playing a huge role in promoting rapid technological improvement of China's mold industry. A large number of emerging private enterprises in China have also realized unlimited business opportunities in this field, and have established hot runner production enterprises, which is of great significance for reducing cost of using hot runner technology, accelerating promotion and application of hot runner technology. However, in general, most of technologies currently provided by local companies in my country are still relatively rudimentary, with small options, unstable quality, and short maintenance cycles, which often affect trust of downstream companies in their products. Therefore, formulating national standards for hot runner components, actively producing low-cost and high-quality components, promoting hot runner technology are keys to development of domestic hot runner molds. .
Compared with cold runner molds, hot runner molds are complicated to operate and maintain.
Improper use and operation can easily damage hot runner parts, making production impossible and causing huge economic losses. For new users of hot runner molds, it takes a long time to accumulate experience.