Screw &barrel of an extruder machine 1,Hardness After Hardending&Tempering : HB240~280 2,Nitrided Hardness 1,Standards of single screw and cylinder of exturder ... machine:20mm--300mm,2,Ratio of length to siameter :L/D ... :abrasion HTP2:corrosion resistance,HTP3:abrasion and corrosion resistance) screw of an extruder machine