A hot runner is a system used in the injection molding process to inject molten plastic into a mold. 

It consists of a heated manifold and several heated nozzles, which are connected to the manifold through a series of channels. 

What is the purpose of a hot runner?

The purpose of a hot runner is to maintain the temperature of the molten plastic as it is injected into the mold, ensuring that it is properly flowable and able to fill the cavities of the injection mold evenly and consistently.

What are the other benefits of using a hot runner system in injection molding?

1. Reduce material waste

First, hot runners can help to reduce material waste, as they allow for more precise control of the flow of plastic into the mold. This can reduce the amount of material that is discarded due to defects or overspray.

2. Reduce labor cost

One of the main advantages of a hot runner system is that it eliminates the need for a cold runner system, which is a channel that carries the molten plastic from the injection machine to the mold cavities. 

In a traditional injection molding process, the cold runner systems would cool and solidify as they traveled through the cold runner molds, and the resulting runner waste would have to be trimmed off the finished parts. 

This not only added to the overall production cycle time but also increased the cost of the parts due to the additional material and labor required to remove the cold runners.

3. Improve the quality and consistency of the finished product

In addition, hot runners can improve the quality and consistency of the finished product. By maintaining the temperature of the molten plastic, hot runners can help to prevent issues such as warping or shrinkage, which can occur if the plastic cools too quickly. This can result in a more accurate and consistent final product.

4. Increase the productivity

Another benefit of hot runners is that they can increase the productivity of the injection molding process. 

Because they can help to reduce material waste and improve the quality of the finished product, hot runners can allow manufacturers to produce more parts per hour, which can lead to increased efficiency and cost savings.

A hot runner technology system maintains the molten plastic at a consistent temperature as it is injected into the hot runner molds, which allows for faster cycle times and eliminates the need for trimming. 

This can result in significant cost savings, as the amount of waste material is greatly reduced and the production process is more efficient.

What are the different types of hot runner systems?

There are also several different types of semi-hot runner systems, each of which is designed to meet the specific needs of different injection molding applications. 

1. Valve gate hot runners

Some common types of hot runners include valve gate hot runners, which use a valve to control the flow of plastic into the mold; 

2. Nozzle-based hot runners

Nozzle-based hot runners, which use a series of nozzles to inject plastic into the mold; 

3. Manifold-based hot runners

Manifold-based hot runners, use a manifold to distribute the flow of plastic to multiple nozzles.

Conclusion

In summary, the purpose of a hot runner process is to maintain the temperature of the molten plastic as it is injected into the plastic injection molds, improving the quality and consistency of the finished product, reducing material waste, and increasing the productivity of the injection molding process.