Optimally matched extruder screw for careful material processing with maximum output performances. Bi-metallic cylinder and hard-faced screws for long life time. Versions with different degassing systems and different screw geometries. Individual design versions matched to various materials. Optionally with controlled variable screw speed. By an optimized screw geometry the shear forces in the ARTEC extruder are lower than with other systems. These reduced shear forces result in perfect material treatment.