ABSTRACT
The fluidity of powder is defined intuitively as the ease of flow and relates to the change of mutual position of individual particles forming the powder bed. The fluidity of powder is strongly related to physical properties such as frictional force and cohesive force of the particles. The flow from hoppers or through an orifice is often considered to express the fluidity of powder. In the field of metallurgy, the time required for a powder sample of 50 g to be discharged by gravitational force from the funnel. The minimum opening size free of choking corresponds to the critical condition for powder flow and can be a measure of the fluidity. Numerous experimental equations4 have been proposed for the flow rate of powder discharged by gravitational force. The powder flow actuated by mechanical force has been studied in relation to torque using various types of rotary viscometers: those of Stomer, Couette, Green, and MacMichael.
