hot runner mould

In recent years, with the rapid development of the plastic industry and plastic moulds and the continuous improvement of general engineering plastics in terms of strength and precision, plastic products have been favored by more and more industries due to their low price and high performance. This has also greatly promoted the development of the mould industry, but with the continuous improvement of the quality and functional requirements of plastic products, especially the transparency and thickness of the product, and how to use a smaller machine to make a larger product, the manufacturing technology of the mould also has a great test. So many mould factories have also made a lot of improvements in the manufacture of moulds, and the use of hot runners is the most prominent.

What is a hot runner?

Hot runner technology is an advanced technology applied to the pouring runner system of plastic injection moulds. The hot runner uses heating to ensure that the plastic in the runner and gate remains molten. It is generally composed of hot nozzles, manifolds, temperature control boxes and accessories. Since there is a heating rod and a heating ring near or in the centre of the runner, the entire runner from the nozzle exit to the gate of the injection moulding machine is in a high-temperature state, so that the plastic in the runner is kept molten, and there is generally no need to open the runner to take out the condensate after shutdown. When restarting the machine, you only need to heat the runner to the required temperature. Hot nozzles generally include two types: open hot nozzles and valve gate nozzles. Since the form of the hot nozzle directly determines the selection of the hot runner system and the manufacture of the mould, the hot runner system is often divided into an open hot runner system and a valve gate hot runner system accordingly.

What are the advantages of the hot runner system?

Normal moulds will use nozzle material, but repeated use will degrade the performance of the plastic. Using a hot runner system without nozzle material can not only reduce the loss of raw materials, thereby reducing production costs. But also, the temperature and pressure in the cavity are uniform, the stress of the plastic part is small, and the density is uniform. Under a smaller injection pressure, a shorter moulding time can produce better products than ordinary injection moulding systems. For transparent parts, thin parts, large plastic parts or high-demand plastic parts, it can show its advantages and realize the production of larger parts with smaller machines.

With the increasing using of hot runner technology, the proportion of hot runner moulds in plastic moulds will gradually increase. During production, the molten plastic flows from the heat distribution plate through the nozzles (gates) of each cavity and enters the cavity. Therefore, when designing the mould, the characteristics of overheating and expansion of mould parts must be considered. Although hot runner mould has the advantages of high production efficiency and low production costs, they also have the following disadvantages: Most of the hot runner mould designs are more complicated and require expensive temperature control systems, so that their manufacturing costs are relatively high.

JNMOULD Co., Ltd. undertakes all kinds of plastic mould processing, injection mould processing, and hot runner mould processing.