What Do You Need to Know About Multi-Drop Hot Runner Injection Mold?

September 27, 2021

Multi-drop hot runner injection molding system has several advantages over traditional course

Basics of injection molding happen to be just the tip of an iceberg. It is because many complexities exist in the industry as a multi-drop hot runner injection mold system.

This step of methodology eventually is a one-step further whilst discussing the injection molding business in comprehensive detail. For this reason, hence, we are from here on going to discuss the basics of the hot runner system along with its apparent advantages over the traditional methods.

multi-drop hot runner injection mold 2021

Due to these advantages, the system thus appears to be challenging the traditional cold runner methods. We are also going to discuss different types of hot runner systems and the disadvantages of the system in the injection molding industry. However, the very first step is the need is to define the system itself. Read more here

What Is the Multi-Drop Hot Runner Injection Mold?

The system of multi-drop hot runner injection mold is a design that includes a two-plate injection molding assembly. The assembly overall comprises a runner-less heated manifold system and along with it contains heated nozzles.

Both of these sub-systems are thereby managed through a temperature control system. The role of these plates ultimately is to keep the thermoplastic material in a molten state as long as possible. After this step, the molten state of the material is thereby injected into the cavity with the help of special temperature-controlled gates.

The gates are also referred to as drops. The drops help in the formation of the final part in a precise manner. In the last step, the final shape gets cooled down by using a cooling system and is thus ejected from the mold.

Different Types of Multi-Drop Hot Runner Injection Mold

Talking about the different types of hot runner systems, let us discuss some famous ones in detail, amongst them are:

Internally Heated Hot Runner System

Internally heated multi-drop hot runner injection mold is the most famous type of hot runner system that offers the most wanted and better flow system in the industry. It is because the system thereby uses torpedo cartridge heaters.

These heaters however attach special thermocouples mounted inside the runners. This eventually allows the system to heat the material from inside out. By using this, the load on heaters is much less than that of the externally used hot runner manifolds.

These features make the system more efficient and effective. This becomes the most needed method when it comes to advanced flow control, the internally heated molds are the perfect methods.

Externally Heated Hot Runner System

When we talk about the externally multi-drop hot runner injection mold system, we are talking about the usage of several temperature control systems.

The systems hence include cartridge heaters, heated pipes, cast-in heater, bands of the heater, coil heater as well as torpedo heaters. These heating systems help in controlling the manifold melting temperature that surrounds the runner challenge.

This makes the system ensure the full transfer of heat that makes it easier to start up. The system becomes more feasible for the material as polymers because they are much sensitive to thermal variation.

Insulated Hot Runner System

The insulated multi-drop hot runner injection mold uses the benefits of insulation properties of the molten thermoplastic material used in the process. For this purpose, the process uses the formation of oversized passages in the molten plates.

In this way, it utilizes insulation properties. By using this system, there is an availability of thick layers of thermally insulated thermoplastic. This helps in freezing around the large diameter of an insulated runner. Hence, it helps the thermoplastic to move through the center of the insulated runner source.

The design of this system however appears to be quite simpler than that of those previously discussed. Moreover, the cost of the production comes lower than that of other traditional methods as an internally heated and externally heated system.

However, this system may result in the formation of uneven design production and filling. The system thereby is famous for heat-sensitive thermoplastic materials and polymers. In short, the method serves best when it comes to changing colors.

multi-drop hot runner injection mold 2021


The system was first introduced in the year 1960s. the system since then appears to be the most adaptive method, however, it went throw many changes and advancements with the passage of time and trends.

Now, with modern technology, the system appears to be the best in injection molding methods. This eventually makes the system carry some favorable advantages that make the system to be famous in the industry. It includes:

Improving the Efficiency of the Mold

The system as we have discussed carries the property to provide the uniformed melting viscosity throughout the system. It also carries a batter pressure injection control that reduces the melt shot capacity hence making it to be the most efficient system.

Less Wastage of Material

When we eliminate the runner, we eventually are eliminating the chances of expensive scrap that causes pots of money.

Fast Cycle Period

The period of a cycle in multi-drop hot runner injection mold tends to get smaller because of the presence of smaller shot sizes.


There are a few drawbacks that we must expect because of so many things going on in these systems. It includes:

More Expensive

The system becomes more expensive as it has more complex molding features. It also carries a high price tag when it comes to its maintenance. Not only this but also energy consumption in old systems get higher.

Complex Operating Requirements

It involves the addition of complex additional hot runner tools and components. Moreover, the additional wear and tear factors in the system cause it to be difficult to manage and operate.

Thermal Sensitivity of Polymers

As we know the system gets too much exposure to additional heat. It thereby makes some thermal sensitive materials such as polymers less suitable for the hot runner systems.

Changing Color Isn’t That Easy

We need to have a multi-step purge of the material that we are using to change colors in the process. The requirement leaves out too much scrap material that appears to be expensive with added machine downtime.

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