Raw material：Medium-carbon steel Pre-treatment：Cold drawing Hardness requirements：HRA58~64 Both of external spline formed by cold forging process,the biggest OD also formed by cold forging process to save raw material,other feature machined by turning,milling and grinding process Tolerance requirements on outer diameter：10 micron Tolerance requirements on inner diameter：22 micron

Raw material：Medium-carbon steel One of external spline and internal spline formed by cold forging process,another external spline machined by gear shaping machine,thread and other feature machined by turning,milling and grinding process Pre-treatment：Cold drawing Hardness requirements：HRA58~64 Tolerance requirements on outer diameter：10 micron Tolerance requirements on inner diameter：15 micron Laser marking with 2D barcode for traceability

Raw material：16MnCr5HH or ZF6 External spline and internal spline machined by spline hobbing process, other feature machined by turning and grinding process Heat treatment：carburizing treatment to HRC 59~63 Case depth：0.4~0.7 mm. Core strength：>=900 N/mm² Tolerance requirements on outer diameter：8 micron Roundness requirements：0.003 Roughness requirements：Rz0.7