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Hot-runner And External Heat Flow Channel
May 23, 2017

Today's markets are increasingly using hot-runner systems, and as with many technologies, the advent of hot runner systems is to do things better and faster with less cost. The cold runner system will cause waste in every open die, in the injection molding parts, the multi-cavity cold runner system can cause a lot of waste of raw materials, which makes the profit space of the mould makers seriously damaged.

The saving of raw material cost is the main power to switch to the Hot runner system, and the other factor is the shortening of the delivery time. Mold makers and tooling manufacturers are increasingly sophisticated in their requirements for process and processing technology, making them more interested in hot runner.

Although the hot runner system has many notable advantages, in order to ensure a suitable and most effective injection molding process, it is necessary to take into account the specific applications, such as the size of the parts, aesthetic requirements, production, raw materials and additives.

In simplifying the injection molding process and reducing the waste of parts, it is important to eliminate the need to spray a large accessory cold runner. The key is to ensure that the melt remains molten throughout the runner system, so that it does not solidify until it reaches the cavity wall where the cavity cools.

Nega Hot Runner

The Nega hot-runner system is the first heat runner system that has been put into market and has undergone several steps. In order to solve the various problems of cold runner, the first project developed is to heat the nozzle, thus creating the most benefit for the production parts. The second approach to the study is the tube-type hot runner system. In this technique, the main stream is heated, the molten resin flows from there to the unheated vertical sprue, and then through the nozzle into the cavity. Another group of molds that appeared at about the same time as the tubular hot runner system began to place the heated probes into each vertical sprue, leading to an unheated insulated runner. The key is to keep the resin in the molten state when it passes through the nozzle because the insulated runner cools in the water and it is difficult to keep the "cycle" running. The three technologies were later combined to form an "internal heating" hot runner system.

The Nega hot-runner system may be more complex than a cold-runner system, but it makes the processing of refractory resins more flexible and reduces the waste of resins. Because the passage is a circular geometry, the internal heating hot runner can well handle the resin that is not excessively sensitive to shearing, and the amorphous material can also be well suited to this technique (except for those materials that are sensitive to residence time, such as polycarbonate)

Until today, because of the high cost of the external hot runner system and the need for some experience, some mold makers still insist on the use of internal heating heat runner system, or even cold flow channel.

Hot Heat Flow Channel

The external heating hot runner begins with a steel brick and is internally fitted with a channel for molten resin. The heater is fixed on the outside of the steel brick from the external heat runner plate, so that it is evenly heated inside. The melt is then dispersed to the heated runner plate, into the heated nozzle, and then to the final water inlet and into the various cavities.

The advantages of the hot runner system are obvious. The design is reasonable, the system can achieve the maximum injection molding capacity at the same time, effectively eliminate the waste of each injection cycle material, achieve a "double win". Hao fully hot runner as a more than 10 years specializing in the production of Hot runner system Hot Runner Company, to the vast number of injection molding products manufacturers strongly recommend the use of Hot runner system, because it can not only save a lot of raw materials, but also for the mold processing process to bring other kinds of convenience.

It is important to note that it is difficult to create a completely smooth, heated trace from the inlet of a hot runner system to each heat tou. Some hot runner systems may be able to achieve this effect, but there are always times in order to prevent the appearance of wire drawing or casting phenomenon, the resin needs to be just at the nozzle to reduce the temperature. Moreover, the flow rate and injection rate have a great effect on the resin processing and color change. The Hot runner system is designed to be suitable for some kind of resin, and it is not uncommon for other resins to be unsuitable. It is usually possible to correct these problems by slightly styling the heated traces. Regardless of the type of hot runner used by the designer, the application of the resin and injection molded parts should be considered.