When you think of scrubbing action, one type of agitator design should come to mind: the ribbon.
Ribbon agitators are just one of the four main types of agitators used in industrial mixing equipment. The other types are paddle agitators, fluidizing paddle agitators and hybrid agitators (which combine the design elements of both paddle and ribbon). Each agitator offers advantages that can speed up mixing, which in turn can help make your production process more efficient and help you save money.
But how do you know if the ribbon agitator is your best option?
“There are many things that need to be taken into account when deciding if a ribbon agitator is right for your particular application,” Bill Noonan, Senior Application Engineer at Marion Process Solutions says.
Here are 4 main factors to consider when determining if a ribbon agitator is the best choice for your application:
“Ribbon agitators are great for low density, free-flowing materials that are similar in shape and size and require a lot of shear work, like powders, sugar and salts," Noonan said.
Ribbon agitators are made up of helixes (three-dimensional curves that move around in a spiral). They are positioned 180 degrees out of phase so the inner helixes push material in the opposite direction as the outer flightings.
The scrubbing and blending motion that double ribbon mixers provide makes them ideal for several applications, including powders, nutraceuticals, pharmaceuticals, chemicals, pet foods, drinks mixes and other types of materials.
Within the category of ribbon agitators, you can choose between single or double ribbon designs. Double ribbon mixers are constructed for continuous, end-to-end mixing with twice the mixing action of single ribbon agitators.
“It’s the back and forth motion, or the scrubbing action, created by the ribbon agitators that allow ingredients to move and roll from end-to-end in opposite directions, which is paramount for getting a good mix,” Noonan said.
With a 4-6 minute mixing time for most dry applications, ribbon agitators offer more thorough blending compared to other agitators. Of course, as with all designs, material characteristics and shaft configurations can affect these mixing times.
Double ribbon mixers are available from one and a half to 600 cubic feet—the same geometry available for paddle mixers.
According to Noonan, ribbon mixers have a capacity that makes them highly versatile and advantageous for small to large batches and any size in between, assuming the mixer is filled an appropriate amount.
For the most efficient mixing, ribbon agitators operate best when filled between 50-100%. In comparison, paddle agitators require 25-100% capacity fill. By carefully considering your desired capacity, the appropriate mixer size can be selected.
Cleaning and Sanitation
Designed with a continuous spiral with no gaps between the ribbon flighting, ribbon agitators are welded to offer the same level of sanitation as a traditional paddle design.
“While the ribbon agitator does have a greater, more complex surface area than a traditional paddle design, the quality of the mix outweighs any additional cleaning effort,” Noonan said.
With the ribbon design, material doesn’t have the chance to clump up as easily and miss getting pulled into the mix. This makes ribbon agitators an appealing option for many applications. However, the best way to know if you’ve got the right agitator for your operation is to test it first.
“When you test your materials, you get knowledgeable engineers working with reliable data to help you get the most out of your mixer,“ Noonan said.
Interested in testing your process in a Marion Mixer?