... external diameterScrew elements introduction:Inner hole shape: involute , six spline , single spline, inner hexagon, cruciate splineKneading block angle: 30/45/60 ... resin,chlorine sulphur polyethylenePowder paintPolyester,ring oxide,lactide,polyurethane,acrylateCERTIFICATION:Extruder screw elements co-rotating twin screw extruder screw and barrel