What is a Vortex Mixer, and When Should You Use One for Commercial and Industrial Coatings?
A vortex mixer is a machine that mixes liquids, like paint or coatings, by creating a spinning motion that looks like a tornado inside a closed container.
This spinning motion, called a vortex, is found throughout nature, often in surprising locations. We see it when the bathtub drains or when a tornado passes, but it also occurs on Jupiter, Saturn, and even the surface of the sun. Vortices are used in magnetic data storage devices, and there is even a branch of physics that studies vortex principles in aerodynamics and other fields. So, how can we utilize this in mixing paint and other coatings?
Understanding the Science Behind Vortex Mixing
To understand how a vortex mixer works, let’s compare it to two carnival rides:
The Graviton (also called Roundup or Centrifuge) is a ride that spins so fast it pins you against the wall. A great ride, but notice that the people inside the ride just follow the rotation of the wall. If you spin a can of paint like this, the paint gets pushed to the sides, leaving air in the middle. It looks a bit like a tornado, but the paint isn’t mixing; it’s just stuck to the walls.
The water slide is another fun ride. Of course, the best ones are both steep and as slippery as possible. As gravity pulls down (red arrow), this results in motion (green arrow) and a lot of screams and smiles! In a vortex mixer, the can is also tilted and the forces are applied so that the liquid inside wants to slide along the sides of the can, like a person on a slide.
Let’s take a closer look at the insides of a closed can and see how these forces and motions create the mixing action of the vortex.
If we simply spin the can like the Graviton and examine a particle of paint or other material, we can see that the centrifugal force, indicated by the red arrow, tends to push the particle toward the outside wall. This applies to every particle of liquid in the can. The contents rotate with the can, and we get a shape that resembles a tornado; however, there is no twisting motion or mixing.
If we spin the can about the vertical axis, called the orbit axis, we get a similar result. This is really just the Graviton except with the can tilted and offset. If this were the only rotation, the forces would want to divide the contents of the can to the far outsides of the can. When spinning starts, there is a brief bit of movement (green arrow) and then the contents catch up to the can and reach a stable position. Again, the middle resembles a tornado without any twisting motion or mixing.
The mixing fun starts to happen when we combine the two motions. Notice that when the particle moves from position 1 to position 2, the forces (red arrows) act in opposite directions. Now, instead of moving to a stable position where mixing stops after a second, the mixture is constantly moving!
Unlike a tornado, the turbulence is on the outside of the vortex (in the liquid) instead of the inside. Since the side of the can is angled, the particles want to slide along the surface of the can (green arrows). We have combined the motions of the Graviton and the water slide!
The way each particle moves applies to the whole contents of the can. The particle in position 1 wants to slide down the side of the can, but when this same particle reaches position 2, forces want to push it up the side of the can. Since forces in position 1 are larger, they overpower forces in position 2, and the particle moves in the same direction, just faster or slower.
The motion of the whole contents is shown by the dashed arrows. When combined with spinning the can, the result is a twisting tornado-like vortex in the liquid. There is an additional mixing effect caused by the tilt of the air part of the vortex. As the can spins on its axis, the vortex remains vertical and acts like a big invisible spoon stirring everything together!
Key Applications of Vortex Mixers in Manufacturing
Vortex mixers are used in many applications. These include:
- Lab Work: Mixing small samples in test tubes and beakers
- Tattoo ink: Making sure colors are smooth and even
- Miniature models: Model paint consistency
- Factories: Large industrial mixers using an impeller
- Printer inks: Accuracy and cleanliness are critical in printing
- Epoxies: Any 2-part coating activated by blending
- Paint: The most common application
Why use a vortex mixer instead of stirring by hand or with another machine? Because it keeps the container sealed, there’s no mess, no need to clean a mixing tool, and no risk of splashing out liquid (which could change the color or ruin the mix). This saves time, money, and keeps the mixture accurate.
Features to Look for in a Commercial or Industrial Vortex Mixer
Not all mixers are created equal. Design matters, especially with thick, hard-to-mix paints, newer low-VOC paints, epoxies, inks, or other difficult materials. The following is a list of features to look for in a mixer.
1. Mixing:
The Radia Speed Demon™ (1) mixer has been continuously optimized to keep up with changes in the paint industry as harder-to-mix low-VOC (Volatile Organic Compounds) paints have become more common. The rotation speeds, angle of the can, internal dimensions, and other factors all affect the size and shape of the vortex and how well the machine mixes.
2. Square Can Version:
If you are mixing square cans, Radia offers the Speed Demon™ SQ. This version can also mix round cans.
3. Easy to Use:
Look for a mixer that is quick and easy to load and unload. The Speed Demon™ mixer lets you just drop in a gallon of paint without clips or additional motion, and the yellow tabs hold the handle upright for quick removal.
4. Quiet Operation:
Loud machines can bother customers or workers. The Speed Demon™ is so quiet that Radia had to add a bright LED light to show when it’s done mixing because people couldn’t tell!
5. Mixing Smaller Cans:
If you need to mix smaller containers (like pints or quarts), check if the mixer has adapters. Radia offers these for their mixers.
6. Size of the Mixer:
In a busy shop, space matters. Radia has minimized the width of the Speed Demon™ to allow the customer flexibility in locating the mixer.
7. Space-Saving Footprint:
Footprint is costly. In the space and motion studies performed by Radia, we realized that most locations require both a table and paint mixers. Radia designed a custom table that fully isolates mixer vibration from the tabletop. This takes a smaller footprint than a table with mixers nearby.
In addition, with the 2 or 4 Wide Ergo Base (2), movements are shorter and faster. Bending over, reaching, and walking are minimized to assist the harried user on a high-traffic day. As a further bonus, the Auto Lid Press on the table quickly and quietly assures a good seal on the lid with no noisy pounding.
8. Custom Mixing Times:
If a special material needs to be mixed for a longer time, just press the button a 2nd time for a longer mix. If desired, the time for each button can be changed to be permanently longer or shorter.
9. Durability:
Durability is built into all Radia mixers, and the Speed DemonTM (3) is not an exception. Durability means that the paint department is always able to sell the product. Service call interruptions are minimized. Replacement of the mixer can be at long intervals of many years or even decades. All of these things lead to a low long-term cost of ownership.
Conclusion
When choosing a mixer, think about both obvious and hidden benefits. Size, appearance, and initial cost are easy to see, but may not be the most important features. The everyday considerations of a better mix, more ergonomic motions, or the customer experience of a quiet workspace may be even more important. Long-term cost of ownership, uptime, and time saved with every can could be the most important considerations of all.