What Is Hot Runner System Of Injection Mold

Introduction

Hot runner system is a kind of injection molding technology used to produce plastic parts. It has mainly hot nozzle, heating elements and cavities. Hot nozzle has the function of heating plastic before it enters the cavity through runner system. Heating elements have position between cavities and nozzles to ensure uniform temperature distribution throughout the entire injection molding process. The cavity contains runners which connect stationary gates on both sides with hot nozzles at one end and exit ports on the other end;

What is Hot Runner System

Hot runner system of injection mold refers to the injection mold which has a heated runner system inside. The melted plastic will run into the cavities through the runner system. It usually consists of a manifold and heating elements, which heat up and connect the nozzle to each cavity. This technology can decrease material wastes, reduce time and improve efficiency.

Hot runner is one of several types of injection molds that provides a way for molten plastic or polymer to fill cavities in an injection molding die when an injecting machine (such as an automatic screw machine) injects them into it at high pressures. Hot runners are machines that are for making plastic parts. They are very good at making parts that have a high flow rate and excellent surface quality. They also have a very consistent temperature, which is important for making sure the plastic parts are made correctly.

Types of Hotrunner System

The hot runner mould is generally divided into two types: one is an internal heating type and the other is an external heating type;

Injection moulding is a process that can be used to create a variety of products design , including automotive parts and electronic devices. During the process, an injection machine uses high pressure to inject plastic into a mould that has been heated to the correct temperature. This creates an object with several cavities or openings that are then filled with more liquid plastic.

When you use hot runners in your production line, they help keep the molten material from cooling down too much before it reaches its destination: your mould. Hot runner systems are used so that you get consistent results every time you run your manufacturing line and don’t have to worry about changing any settings on your machines every time something in your factory changes (like if there’s an issue with one of your materials).

Internal heating

Internal heating type refers to the use of heating element placed in the hot nozzle or hot cavity of the mold. These hot nozzles or hot cavities heat plastic from inside. This kind of hot runner system is actually a kind of injection molding machine where the nozzle become hot by the element, but its assembly is with the injection molding die;

External heating

External heating type refers to using heating elements around or at both ends of hot runner system. It heats plastics in a very similar way to injection moulding machines. The main difference is that there are no screws or plungers in external heater hot runners.

Another type of hot runner system is the internal heating type. In this case, plastics melt when they go through the screw and nozzle system and then enter into mould cavity for solidification and cooling down process before ejection from the mould.

The Hot Runner System advantages are as follows:

1. Improve melt quality and increase production efficiency

Hot runner systems are an important part of injection molding. They help to improve melt quality and increase production efficiency by making sure that the low-viscosity plastic material is flowing through better-heated channels.

2. Different parts need different color

Different parts need different color, which can only be ready using multiple runs in cold-runner system, while with hot-runner system, multi-color production can be ready in one run;
Color change requires more time and labor costs: In a cold runner molding process, each part must undergo a separate cycle of molding. Therefore, the final product will be produced at different times. If it is desired that all parts have a uniform color and appearance after running several cycles or steps of injection molding machine operation cycle, then it must be taken into account when designing the whole process.
Cost savings: After repeated runs in your cold runner injection molding machine to produce multi-colors on parts or components for mold manufacturers in China products (such as automotive components), you will feel tired because there is no effective solution yet for solving this problem until now! However with hot runner systems available today such as APC/Nova/FastRunner or other brands we can now offer various solutions that allow us to save money by eliminating multiple cycles per part thus reducing overall production time while increasing efficiency by operating on just one cycle while still achieving good quality results every time!

3. Better part quality

The quality of the product is also an important factor. In two-shot molding, the contact area between two materials is smaller than in traditional injection molding. This makes it easier to ensure a good workpiece quality. In addition, the core and cavity parts do not touch each other directly on the same plane. Their temperature can be lower with water or air after injection, which reduces shrinkage of raw materials and achieves high dimensional accuracy.

4. Decrease material costs

Injection molding is a process that requires the use of raw materials, which run melted and injected into the mold through a nozzle. Once the material cools down, it produces a finished product. If you want to reduce your expenses, then you should look for ways to decrease excess material and scrap. Hot runner systems can help with the issue of filling every single cavity on an injection mold tool. They allow for precise control over how much plastic flows into each cavity during injection molding cycles. This means that you don’t have to use additional material or scrap when filling each cavity.

5. Less cycle time

When the hot runner system get installion, the heating and cooling systems of all cavities can have a control by a single thermocouple. When one cavity reaches its peak temperature, it will not take long to reach the same temperature with other cavities.If two different temperatures are for each cavity, it will reduce power consumption significantly.

6. Assembly process easier

Zero scrap rate.
Assembly process is easier because there are no crack lines in the parts.
This system also makes assembly process easier because there are no crack lines in the parts; this means less time to put together, which leads to fewer mistakes and lower cost.

7. Valve gate

The hot runner system is an essential part of injection molding machine and have two types:

The fixed cold runner system
The movable cold runner system

Conclusion

Hot runner system has many advantages, but it also has some disadvantages: 1. If the equipment has poor maintainance, the hot runner system may fail and affect production; 2. If there is no air supply or power supply during operation, it will lead to mechanical failure; 3. The parts must be hot before entering the molding machine so that they are free of damaging by cold temperature during injection molding process; 4. The formation of a certain amount of residual stress in parts due to material contraction from heating process inside each cavity when cooling down after molding cycle is ready.