In counterrotating screws where the profiles are conjugated the material remains enclosed in C-shaped chambers and there is no motion of it along the channels therefore a plug flow occurs. In corotating screws however even when they have conjugated profiles there are passages from one screw to the other. Lf the flight-tip width is E than is as large as possible as we have seen there is one passage if it is smaller there are two. In any case the material flows from