A flow visualization study of starve fed solids conveying in single screw and a modular self-wiping co-rotating twin screw extruder is observed inflow visualization experiments. Single screw extruders exhibit forward Archimedean transport of material on the undersides of the screw. Self-wiping co-rotating twin screw extruders conveying forward in the intermeshing region and in the region near the apex between the screws. Observations are reported of the melting of solid pellets and possible melting mechanisms are discussed.