Inner diameter: ≥8mm Outer diameter: ≤800mm Thickness: 3 to 20mm Any length, any pitch and both rotating directions We have three manufacturing process according to the size of screw-flight: 1) Continued cold rolling when it has 3-5mm thickness, inner Dia. ≥20MM, outer Dia. ≤800MM. 2) Continued twisting when it has 3-20 thickness, inner Dia. ≥8MM, outer Dia. ≤2MM. 3)Stamping and extending which adapted for any product but need making specified mold These materials, which can be low-carbon, manganese and stainless steel, can meet the requirements of customers from different way.