A ribbon blender uses a shear and convection mixing principle to blend the ingredients. The rotating blades create high shear forces, resulting in a smooth consistency. A ribbon blender helps mix frozen foods and smoothies.
Shear
The principle of blending using a ribbon blender is known as shear. First, the materials are loaded into the blender until it reaches 40% to 70% of their volume. The ribbons are then allowed to rotate with the help of the drive system. This process can produce homogeneous blends in a short time. Afterward, the materials are discharged from an opening at the bottom of the trough.
The ribbon mixer is a versatile instrument that mixes wet, plastic, and finely divided solids. It can also be used for mixing liquid-solid and solid-liquid mixtures. In addition, it is a good choice for mixing liquids with solids, mainly if the mixture contains large amounts of solids.
Ribbon blenders have two main types of blades, the inner and outer helical ones. The outer one is narrower, while the inner one is wider. Both are ideal for mixing liquids and solids. They have a wide range of applications, including coating and heating. However, ribbon blenders are not the best choice for mixing free-flowing materials, as the materials can get ground up in the process.
Convection
Ribbon blenders operate on two mixing principles: convection and diffusion. Convection is turning large solid particles over in the blender, while diffusion is the movement of individual particles in the liquid. Therefore, the efficiency of the ribbon blender depends on the particle size and bulk density.
The ribbon blender moves particles in two directions, which is essential for homogeneous blending. As a result, it produces less shearing force than a planetary mixer. The ribbon blender is often used for mixing solids that contain small particles, wet masses, and plastic solids.
Diffusion
The Diffusion Principle of Ribbon Blenders works to achieve a homogenous blending of the ingredients. The ribbons move in a radial pattern, with the outer ribbons moving faster than the inner ones, along a horizontal axis. This results in uniform mixing within a short time. Most ribbon blenders achieve homogenous blending within 15 to 20 minutes of start-up. The efficiency of mixing depends primarily on the particle size of the ingredients. Ingredients with uniform particle sizes tend to blend more quickly.
Ribbon blenders can be configured to meet specific mixing needs. They use convection and diffusion. Convection mixing occurs when large solid particles move over an agitator assembly, while distribution occurs when individual particles move.
A ribbon blender’s mixing efficiency is affected by the ingredients’ particle size and bulk density. Ingredients with similar bulk density will mix more efficiently than those of different particle sizes. Batch size is also a critical consideration. A ribbon blender should be at least 30% of its stated capacity to ensure proper mixing without dead zones and clumps.
Direct-drive
A direct-drive principle of a ribbon blender can be used for blending dry powders into wet mixtures. These blenders have bulky gauge walls with strong end panels to control the agitator’s movement. They are built with solid stands to prevent the blender from collapsing, and all their components are internationally certified. The ribbon blender’s mixing capacity depends on the size and density of the raw materials. The agitator is equipped with atomizing nozzles that disperse the liquid. In addition, the liquids are discharged at the bottom of the trough through a valve that can be manually or pneumatically operated.
Ribbon blenders combine a slurry pump with agitator blades. This system helps in blending materials by moving them from the center to the outer edges. This axial movement is caused by the difference in peripheral speeds, which produces homogeneous blending. Most ribbon blenders achieve homogeneity in 15 to 20 minutes after start-up. In addition, modern ribbon blenders use a gearmotor instead of a belt drive, which requires less maintenance. They also feature adjustable starting torques and overload protection.