What is Mix Accuracy or Homogeneity?

The mixing accuracy or homogeneity indicates the degree of how well it has been mixed.

There is no universal definition of homogeneity for powder mixes, due to the large number of types of mixes with very different physical properties. In addition, the use of the end product is also relevant in determining the mixing accuracy. In general, the CV variation coefficient is used as a measure of the mixing accuracy. The coefficient of variation is the ratio between the standard deviation and the mean:

The CV is determined by taking several samples from different places from the mixer and analyzing them. The achievable homogeneity with a paddle mixer is generally very high. Segregation usually takes place after the mixing process, for example during the transport phase. During transport, the large parts can “float” up again. This is segregation by percolation. This can take place after mixing, but also further down the chain. This can arise, for example, in the transport of the end product to the customer. The segregation then takes place in the final packaging intended for the consumer. For example muesli, where the large parts are at the top of the package. But other forms of segregation can also occur after mixing.

Another form of mixing inaccuracy is lump formation, also called agglomeration. This is desirable for some products such as washing powder, instant soup and instant coffee cocoa. However, in most powder blends this is undesirable and is seen as blending inaccuracy. This can occur, for example, when liquids are not applied correctly or in large quantities.