Modular extruder barrel construction

An extruder characterized by a plurality of barrel modules arranged in alignment, at least two adjacent barrel modules having a plate secured between each pair of adjacent barrel modules, each plate and each barrel module being interchangable, each plate being formed of two or more arcuate parts each plate having an opening passing therethrough and comprising projections extending into said opening, the opening of the plate and internal surfaces of the barrel modules forming a substantially continuous passageway which provides an extrusion chamber of a barrel of the extruder and a screw in the extrusion chamber having one or more helical flights projecting from a root portion of the screw, the flights being discontinuous and arranged to leave annular spaces between adjacent flight sections into which the projections extend towards the root of the screw, the barrel modules being provided with external flanges extending around end portions thereof, the flanges containing a plurality of bore holes which correspond to bore holes passing through a respective part of a plate around the external circumference thereof, so that the plate parts are secured between two adjacent barrel modules by fastening means inserted in aligned bore holes of the plate parts and external flanges, and the plate parts are removable in a radial direction when the fastening means are removed from the plate parts.