The Importance of Cooling Channels

Uneven cooling is responsible for many common defects in injection molded parts, so cooling channels are a critical component of mold design that helps parts cool at the same rate throughout the part. What are cooling channels? Are there different types of cooling channels?

Here’s what you need to know about cooling channels so you can incorporate them into your mold design.

What Are Cooling Channels?

As the name suggests, cooling channels are channels in a mold through which a cooling agent (like coolant or water) can flow to accelerate the cooling process and make it more uniform.

Why Are Cooling Channels Important?

Insufficient or improper cooling channels can cause a number of problems, including:

  • Insufficient or uneven cooling can lead to deformations throughout the part as areas cool at different speeds. Proper cooling prevents parts from warping or shrinking.
  • Part defects can decrease productivity if cycles need to be re-run or if rework is needed to get deformed parts to spec.
  • Cooling usually takes up to 75% of cycle time, so you must carefully control it. Additional cooling time can significantly increase cycle and production time.
  • Part defects increase production costs.

Types of Cooling Channels

For decades, the only way to create cooling channels was to drill or mill them into a mold. Thanks to 3D printing technology, there are now two different types of cooling channels.

Standard/Traditional Cooling

Traditionally, cooling channels were straight lines created by drilling or milling into the mold. Standard cooling channels may cross or be enhanced with other devices like bubblers or bafflers. Traditional cooling channels are still a good option for parts with fairly simple geometries to ensure the whole part cools effectively.

Conformal Cooling

Conformal cooling channels follow (conform to) the shape of the part being molded. They are usually made with metal 3D printing (also known as direct metal laser sintering or DMLS). DMLS is an additive manufacturing technology that makes parts from 3D CAD models by melting metal powder with a focused laser beam, layer by layer, in layers as thin as 40 µm.

3D printing can create complex internal structures that would be impossible to make conventionally, so inserts for mold tools can be customized with cooling channels to fit the geometry of the part.

Since conformal cooling channels don’t need to be in a straight line, they can follow any curvature and the cross-sectional shape of the channel can vary anywhere along its length, which is impossible to do with traditional cooling channels. With these characteristics, conformal cooling channels offer better cooling efficiency and faster cycle times.

Injection Mold Cooling System Design

Regardless of which type of cooling channels you use, there are several important factors you must consider in your design, including:

  • Cooling channels should be as close as possible to the thickest part of the mold cavity.
  • Multiple smaller channels work better than one large channel.
  • Keep larger cooling channels the same diameter throughout the mold.
  • Ensure both halves of the mold cool consistently.
  • When choosing mold materials, consider heat transfer for more effective cooling.

Design Aspects of Cooling Channels

The following design aspects of cooling channels can help achieve good channel design.


Bubblers are small channels running off the main channel that allow coolant to reach more surface area of a part. Coolant runs through the tube of a bubbler and flows down the outside of the tube and returns to the primary cooling channel.


Baffles are shaped like a semicircle and run at a right angle to the main cooling line. Baffles increase the surface area coolant reaches while the coolant flows through one side of the baffle and out the other.

Thermal Pins

A process that can continually repeat itself throughout each cycle, thermal pins are filled with a fluid that cools by taking heat from the mold, vaporizing, and condensing back to liquid when the coolant reaches it.

Learn More or Get a Quote Today

To learn more about how to incorporate cooling channels into your mold design or to request a quote, click here or call 1-888-893-1587. Universal Plastic Mold (UPM) is an American injection molding company with more than 50 years of experience.

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