Powder particles are observed to have different shapes. Particles shapes are spherical, out of round, blocks or cubes, flakes, or irregular shapes (see figure 1).
The Conveyor Equipment Manufacturing Association (CEMA) defines the shape of the individual particles as follows :
Agglomerated - Several individual particles bonded together.
Angular - Sharp-edged or having a multi-faced, irregular shape.
Crystalline - Of geometric shape or multi-faced regular shape.
Cylindrical - Cylinder-shaped.
Dendritic - Having a branched, crystalline shape with the branches extending from the faces of the body.
Fibrous - Regularly or irregularly thread like with a flexible structure.
Flaky - Plate-like.
Needle-like - Long, thin, rigid, straight, and pointed.
Out-of-Round - Similar to spherical but being somewhat deformed or elongated.
Spherical - Globe-like.
The inter-particle powder friction depends on the shape of the particle . As a result, flowability of material within the blender is affected by the particle shape.