Types of screw:
▪ Gradual、saltation、wave、screen、double screen、distributary、separating、exhausting、dowel、mixed、smelting、double screws、three screws、granulating、etc.
▪ Materical:38CrMoALA
▪ Hardness after quenching and tempering:HB260-290
▪ Diameter:∅15-300mm
▪ L/D：4-35
▪ Hardness after nitridation：HV900-1000 ▪ Depth of nitrided layer:0.5-0.7mm
▪ Brittleness after nitridation ≤second level
▪ Suface roughness：Ra0.4μm
▪ Straightness:0.015mm/m
▪ Inside&outside diametre tolerance :≤0.02mm
▪ Circular run-out：≤0.04mm
▪ Screw length tolerance：≤0.03m
▪ Key&spine tolerance grade ：Grade 7
