Why is shear sometimes needed during mixing?

Raw materials are mixed together during a mixing process. In some mixtures lumps or so-called fish eyes can form. This is caused by different substances coming into contact with each other, one or more substances of which are sticky or because moisture is added. Fish eyes form clumps that are dry on the inside and moist on the outside. Fish eyes can also result from improper spraying of liquids. When greases are sprayed onto dry powders, there is a risk of agglomerates forming. Clumps can also already be present in the pre-dosed raw materials. Shear during the mixing process can reduce some of these problems.