Multi-Step CNC Turned
Stepped Shafts

A stepped shaft is a shaft with multiple cylindrical sections of different diameters, connected by shoulders (steps). Each step serves a different function: bearing seat, gear fit, seal running surface, thread zone, or coupling end. Stepped shafts are the most common shaft type in gearboxes, motors, and actuators — a single shaft combines all these functions, avoiding the need for multiple mating parts.

Concentricity (coaxiality) between all stepped diameters ensures that bearings, gears, and couplings mounted on different steps all share the same rotational axis. Poor concentricity creates a bent-shaft condition — even if every individual diameter is within tolerance — causing vibration, premature bearing wear, and noise. HXC machines all stepped shaft diameters in a single 5-axis turning-milling setup, achieving concentricity ≤ 0.005 mm TIR between all steps.

Individual bearing seat diameters: IT5 (±0.005–0.010 mm depending on diameter) ground after hardening. Step shoulder runout to adjacent bearing seat: ≤ 0.005 mm. Thread runout: ≤ 0.01 mm. Spline or keyway positional tolerance: ≤ 0.010 mm. All measurements reported by CMM.

Yes — internal features including centre bores, axial through-holes, radial cross-holes, internal threads, and blind bores are all machined in the same setup as the external stepped profile. Common examples: stepped shafts with internal coolant through-bore; hollow stepped shafts with internal keyway; stepped shafts with axial M6 tapped holes for end-cap fasteners.

Prototype (1–5 pcs, turned + ground): 5–8 days. Small batch (10–50 pcs): 8–12 days. Production (100–1,000 pcs): 10–16 days. Stainless or titanium: add 2–4 days. Rush production available.

42CrMo4 (induction hardened) for industrial and automotive. 20CrMnTi (carburized) for maximum surface fatigue and EV drivetrain. C45 for BLDC and general motor shafts. SUS303/316L stainless for food, pharma, marine. Al 6061/7075 hard-anodized for lightweight. Ti Grade 5 for aerospace/medical.

Standard ground OD: Ra 0.4 µm. Precision bearing seats: Ra 0.2 µm. Mirror finish for seals: Ra 0.1 µm. All measured by contact profilometer and reported on the inspection certificate.

Yes — keyways, splines, threads, cross-holes, flats, and tapers are all machined in the same 5-axis turning-milling setup, ensuring concentricity between all features within 0.003 mm TIR.

Maximum shaft length between centres: 1,200 mm. For shafts over 600 mm, straightness correction after heat treatment is performed before final grinding. Specify the required straightness tolerance on your drawing.

A complete stepped shaft drawing should show: every diameter with tolerance and surface finish; every step shoulder with perpendicularity and runout callout relative to the bearing seat datum; all thread specifications (standard, pitch, class); keyway/spline profile and standard; and hardness requirement for each zone. HXC engineers can help interpret incomplete drawings — send a sketch and we will confirm geometry before quoting.