Study of the effects of feed frames on powder blend properties during the filling of tablet press dies

This paper studies systematically the effect of a feed frames, a device used in rotary tablet presses to drive the powders into compression dies, on the properties of the powders entering the tablet press dies. The work focused on the effect of blend composition, feed frame parameters (blade speed, residence time), and rotary die disc parameters (die disc speed, die diameter) on the flow pattern, uniformity of die filling, applied shear, and the flow properties of pharmaceutical blends. The flow pattern suggests a stratified filling of the dies and therefore, non-uniform properties of the tablets. The amount of powder entering the dies depended on blend flow properties, feed frame speed, and dies disc speed. In addition, blend properties changed significantly as the powder flowed through the feed frame. The flowability of lubricated blends improved significantly as the number of feed frame blade passes increased, decreasing in turn the RSD of the die filling weight.