Characterization of the sphericity of particles by the one plane critical stability

— A method has been developed to characterize the roundness of particles in terms of the angle necessary to tilt a plane such that the particles would roll, the ‘one plane critical stability’. The method is based on determination of the centre of gravity of the particle from a digitized image of the coordinates of its outline and computing the angle necessary to incline a plane such that the centre of gravity moves outside the boundary of the particle. The method is particularly applicable to differentiate between the various shapes formed during the production of spherical granules by extrusion/spheronization.