Development of vibration shear tube method for powder flowability evaluation

A new method for evaluating powder flowability, named vibration shear tube method has been developed. In this measurement system, the powder was discharged through a narrow gap between a vibrating tube edge and a flat bottom surface, where the particles experienced high shear forces to overcome the adhesion and friction forces. The vibration amplitude was increased during the measurement, and the mass of particles discharged was measured at constant time intervals. The amount of powder used for the measurement was about 10-40. g. The measurement time was 100-400. s. A series of experiments was carried out using alumina particles of 2-60μm in mass median diameters. Flowability profiles, i.e. the relationships between the mass flow rate and the vibration acceleration were obtained experimentally. To characterize powder flowability, critical vibration acceleration and characteristic mass flow rate were proposed. The values of these factors were analyzed in detail and the performance of this measurement system was evaluated.