The V-Blender is a popular tumble blender commonly used in the pharmaceutical and food industries. V-Blenders are used for mixing, lubricating and blending in Pharmaceutical, Nutraceutical, Food, Chemical, cosmetics, ceramics, pesticide, plastics and other Allied industries. This article explains the design, construction, and operation of the standard V-Blender. ‘V’ Blender, the rotating shell V-Type Blender is used only as dry mixers and have no packing glands (seals) around shafts entering the chamber to eliminating problems of cross contamination.
The V-Blender is made of two hollow cylindrical shells joined at an angle of 75° to 90°. The blender container is mounted on trunnions to allow it to tumble. As the V-blender tumbles, the material continuously splits and recombines, with the mixing occurring as the material free-falls randomly inside the vessel. The repetitive converging and diverging motion of material combined with increased frictional contact between the material and the vessel’s long, straight sides result in gentle yet homogenous blending.
The primary mechanism of blending in a V-Blender is diffusion. Diffusion blending is characterized by small scale random motion of solid particles. Blender movements increase the mobility of the individual particles and thus promote diffusive blending. Diffusion blending occurs where the particles are distributed over a freshly developed interface. In the absence of segregating effects, the diffusive blending will in time lead to a high degree of homogeneity. V-Blenders are therefore preferred when precise blend formulations are required. They are also well suited for applications where some ingredients may be as low as five percent of the total blend size. Normal blend times are typically in the range of 5 to 15 minutes depending on the properties of material to be blended.
The charging of material into the V-Blender is through either of the two ends or through the apex port. Studies on V-blenders have demonstrated that for solid powders which have similar size and shape, there is no mechanism to move the powders across the line of symmetry of the blender. For such materials, care must then be taken to load each side of the blender equally to ensure the desired homogeneity of blends.
Blending efficiency is affected by the volume of the material loaded into the blender. The recommended fill-up volume for the V-Blender is 50 to 60% of the total blender volume. For example, if the fill of material in the blender is increased from 50% of the total volume to 70% of the total volume, the time taken for homogenous blending may be doubled.
Advantages of Using V-Blender:
Disadvantages of V-Blender:
V-Blenders designs are most often used for the dry blending of free flowing solids. This blender is often used for pharmaceuticals, but the mixing action’s slight shear limits the blender’s use for some very soft powders or granules. V-Blenders are generally used for the following: