The types of feed devices used in the industry vary from rotary valves to vibratory tray devices and screw feeders (single and twin screw types). However, as with any process, the product flow characteristics will often determine the best feed method. Since most pharmaceutical powders and formulations can have difficult flow characteristics, the twin screw feeder is often the method of choice. The “self-wiping” action of the intermeshed screw flights lends itself perfectly for the feeding of difficult and cohesive powders.