Different Types of Mold Cooling Channels: Enhancing Injection Molding Efficiency

Table of Contents

Cooling channedl design
Cooling channel design

I. Introduction

An essential question that often gets asked in injection molding manufacturing is what would be the likely outcome of ineffective mold cooling channels in injection molding? The effects are numerous. But we know that the efficacy of cooling channels in injection molding is significant in minimizing cycle times, ensuring the optimal use of materials, and enhancing part quality. It is for these reasons cooling channels are designed with keen meticulousness.

Its ability to dispel heat while regulating its temperature ensures cycle times are minimized. With that, manufacturers can perfectly manufacture market-worthy items.

Let’s go a step further by taking an in-depth look into mold cooling channels.

Simulating pressure temperature and flow rate
Simulating pressure temperature and flow rate

II. Understanding Mold Cooling Channels

Every mechanical tool deserves a cooling mechanism. In the case of injection mold, its cooling channels are responsible for maintaining a controlled temperature. In essence, it simply presents the best way to expel heat. This process also permits the proper formation and solidification of the molded part while maintaining a high-quality part production.

As for the principle of heat transfer which is employed in the injection molding process, expelling heat from the mold to allow parts to form excellently, void of complications and defects is the objective. Incidentally, the heat from the plastic is transferred to the cool surface within the mold by a coolant. The results obtained are cooling channels maintaining a consistent temperature required for part formation.

Baffles and Bubbler cooling system
Baffles and Bubbler cooling system

III. Types of Mold Cooling Channels

Several types of mold cooling channels exist in the injection molding industry. However, we have highlighted the most common ones with extensive use cases below.

1.  Conventional Cooling Channels

Straight-line cooling channels are conventional channels that allow liquid coolants to flow through the mold. This way, the coolant can extract the heat from the molded plastic within the mold. Heat dissipation via this cooling channel keeps the mold cool for optimal performance. It’s one of the most sought-after cooling channels due to its simplicity in design and maintenance.

The design of straight-line channels is such that it works efficiently in proximity to the mold’s cavity. However, the proximity must be meticulously crafted so it doesn’t impair the part’s quality. In addition, they work best with simpler dimensioned parts.

2.  Baffle Cooling Channels

Baffles function optimally and efficiently by ensuring the coolant flows through the most complex parts. This allows the coolant to extract heat from crevices conventional cooling channels may not be able to get to. Furthermore, baffles ensure a longer flow of coolant typically fostering consistent temperature control.  Baffles employ the use of thin plates that control the flow of the coolants within the cooling channels.

A major merit of the baffle cooling channel is its reach. More importantly, its ability to maintain regulated cooling increases the chances of producing dimensionally uniform parts. Baffles are often used in producing automotive components.

3.  Bubbler Cooling Channels

The design of the bubbler cooling channel creates an effective operation system. Just like the baffle cooling channel, bubblers encourage deep cooling into areas conventional cooling is unable to reach. The flow of the coolant begins from the inner tube, runs through the mold, and travels back through the outer tube. Think of it as a slight upgrade to the baffle cooling channel, and tubes are used in place of thin plates.

Bubbler cooling channels thrive in complex geometries, especially designs with intricate dimensions with deep cores. The automotive part manufacturers.

4.  Conformal Cooling Channels

Innovation continues to make its mark in manufacturing, and yet again in cooling channels.  The prowess of additive manufacturing such as 3D printing techniques is evident in its ability to function excellently. Conformal cooling channels are an advanced cooling technique that employs a 3D printing method. This cooling system is integrated with the formation of the mold cavity. Conformal cooling channels align the functionality of 3D printing with the engineering brilliance of injection molds to create a cooling system that cuts down cycle time and eliminates the possibility of defects.

When high precision and part quality are top priorities, conformal cooling steps up to the challenge, hence its application in the production of high-quality medical and aerospace parts. Its cooling efficiency is unrivaled even with complex geometry parts.

5.  Spiral Cooling Channels

As its name suggests, the spiral cooling channels are most efficient in the production of cylindrical plastic parts. Its spiral form aids the flow of coolant in a spiral pattern. This enables the coolant to effectively minimize temperature.

Spiral cooling channels are suited to specific molds and part production. Its application is mainly utilized by manufacturers of packaging tools. For this reason, round and cylindrical components are cooled by the spiral cooling channel. The coolant flows nonstop around the mold to seamlessly dispel the heat from the mold. Spiral cooling channels are also space-efficient

6.  Thermal Pins and Heat Pipes

Thermal pins and heat pipes may seem unthinkable to use as heat transfer mechanisms, but with the adoption of phase change and thermal conductivity, they prove to be an innovative heat transfer type. This form of heat transfer expels heat quickly by using metal rods with extensive thermal conductivity. Meanwhile, heat pipes are armed with fluids that assist with the extraction of heat from the mold.

For quick and specific heat transfer, thermal pins and heat pipes may be your best bet. They dispel heat from specific points in the mold where heat transfer seems complex. Thermal pins and heat pipes swoop in to ensure the consistent formation of the molded part.

Plastic Injection molding Design
Designing Cooling Channels

IV. Design Considerations for Cooling Channels

The design considerations for cooling channels are first determined by the placement of the cooling channels within the mold. Considering its importance in the overall injection molding operation, placing cooling channels within the mold must be a calculated strategy.

This entails determining its closeness in the mold for efficient heat transfer and extraction. In addition, mold designers must also consider the mold’s dimensions in comparison to the part to be produced. This will further assist in the proper placement of the cooling system. The ultimate goal is compactness, and even formation of the part while reducing cycle times.

The ideal design consideration that comes next is channel diameter and spacing. The importance of these factors cannot be overstated. How so you may ask? The channel diameter conditions the amount of coolant that can flow through the cooling channels.

A larger diameter translates to heavier coolant flow. This in turn results in faster and enhanced cooling. But with a smaller diameter, the reverse is the case. The requirements for spacing are so that the cooling rate is even across the board.

Nonetheless, the inadequate spacing could lead to thermal interference or weakening of the mold’s framework. Thus, the use of Computational Fluid Dynamics (CFD) by mold engineers is birthed.

Material selection for cooling efficiency is equally as important as the aforementioned considerations and here’s why. Often the thermal conductivity of the material chosen is high and only materials such as aluminum and copper offer such thermal conductivity.

The flip side to this is they are quite expensive. Nevertheless, manufacturers have found alternatives in hybrid materials. A perfect example is a steel mold with copper inserts. The cooling efficiency of such hybrid material is outstanding. This balances out the cost, performance, and thermal conductivity for cooling efficiency for manufacturers.

Furthermore, the coolant selection is critical as it must be compatible with the cooling channel materials. Let’s not forget that regular checks and maintenance enhance the cooling capacity of these channels.

simple cooling system
Simple cooling system

V. Cooling Channel Performance Factors

A vivid way to illustrate how heat transfer works efficiently is by imagining a car radiator at work. The mold’s capacity to expel heat without complications is a testament to its cooling channel efficiency. Consequently, heat transfer is a huge marker for cooling channel performance. A few factors that the cooling channel relies on for its optimal performance include the design of the cooling channels, the flow rate of coolant, choice of coolant, and thermal conductivity of the cooling channels. The design of the cooling channel considers the diameter and spacing which directly influences the flow rate of coolant. Additionally, copper and aluminum are the materials with the highest thermal conductivity.

Another cooling channel performance marker is cooling uniformity. We don’t need a soothsayer to spell out the consequences of uneven cooling, hence the necessity of uniform cooling. The major determinant of uniform cooling is cooling channel placement and mold design. The placement of cooling channels is essential to uniform cooling with a primary focus on heat-concentrated spots. When designing the molds, the appropriate cooling channel type must be meticulously selected to suit the injection molding process. This fosters cooling saturation over the mold. Not only will the parts produced be exceptional, but also aesthetically pleasing.

The most efficient way to reduce cost and save time in manufacturing is by reducing cycle time. However, cycle time reduction also depends on the efficiency of cooling channels. In the same vein, the quality of the part being manufactured also relies on cooling channel efficiency. Seems to us like the world depends on the efficiency of cooling channels don’t you think? The mold’s capacity to dispel heat quickly means more components are manufactured in no time. That also means there is cooling uniformity that guarantees part quality. So, with optimal heat transfer and cooling uniformity, cycle time is reduced and excellent parts are produced.

VI. Challenges and Solutions in Cooling Channel Design

In the manufacturing world, there are typical challenges that lead to groundbreaking solutions. One such common problem in cooling challenge design is clogging. This typically stems from the buildup of debris and corrosion in the cooling channel which automatically impairs efficient heat transfer. Uneven cooling is no doubt a result of irregular placement of cooling channels. That directly interprets defects in the parts.

Simple solutions are what these aforementioned common problems require. It begins with regular organized flushing of the cooling channels that will discard any debris clogging the channels. In addition, filtered coolants can be incorporated. This will prevent any foreign contaminants from entering the channels. Simultaneously, routine checks and inspections are necessary to avert future complications. Considering the improper placement of cooling channels, realignment will ensure uniform cooling.

In combating these common problems, design improvements in cooling channels will extensively mitigate the looming doom. The adoption of bubblers and baffles can help cushion the effect of irregular cooling leading to defects. Furthermore, conformal cooling can be implemented with the aid of 3D printing. These various types of cooling channels are empowered to overcome these challenges. Computational Fluid Dynamics (CFD) simulations can also assist with appropriately placing the cooling channels.


In a nutshell, mold cooling channels play an integral part in enhancing injection molding efficiency. Understanding their basic principles helps to ascertain what type of cooling channel to adopt per production cycle. Each type is armed with efficient functions to tackle challenges that may arise. Furthermore, design considerations for cooling channels are important factors to be examined.

Conclusively, optimizing mold cooling channels for better performance is assured if performance factors such as heat transfer efficiency, channel diameter and spacing, and material selection are carefully considered. Without a doubt, cycle times will be shortened and part quality guaranteed. 


Gary Liao

Gary Liao

Gary Liao is the Engineering Manager of TDL Company and has more than 20 years of mold design experience.

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