ClassA Motor

Raw material

Motor Shaft

Bar cutting → CNC turning & keyway / D-cut → Heat treatment → Cylindrical grinding → Cleaning, rust protection & inspection

✓ Expert reviewed All content on this page has been reviewed by a senior motor engineer.

Process flow

5 main process steps, with the equipment and instruments used at each step, their main suppliers, and the technical control points.

  1. 1

    Bar cutting

    Cold-drawn or ground bar stock (SUS420J2 / C45) is cut to length.

    ⚙ CNC Lathe / Turning CentreAutomated
    International
    MazakGuangzhou, OkumaGuangzhou, DMG MORI
    Mainland China
    MinjiaGuangzhou, JSWAYZhongshan, Haitian Precision

    Technical control points:

    • ▪Material grade — Matches the drawing (mill certificate + composition)Check: Mill certificate check; spectrometer per lot
    • ▪Bar straightness — ≤ 0.5 mm/mCheck: Straightedge / rollers; per lot
  2. 2

    CNC turning & keyway / D-cut

    Shoulders, grooves and the shaft extension are turned; the keyway or D-cut is milled.

    ⚙ CNC Lathe / Turning CentreAutomated
    International
    MazakGuangzhou, OkumaGuangzhou, DMG MORI
    Mainland China
    MinjiaGuangzhou, JSWAYZhongshan, Haitian Precision
    ⚙ CNC Machining CentreAutomated
    International
    MazakGuangzhou, OkumaGuangzhou, DMG MORI
    Mainland China
    MinjiaGuangzhou, Haitian Precision

    Technical control points:

    • ▪Diameters and grinding allowance — Allowance 0.1–0.2 mm on diameter at ground seatsCheck: Snap gauges / micrometer; first piece and SPC
    • ▪Keyway width and position — Width to N9 / JS9; symmetry per drawingCheck: Key gauge; first piece and periodic
    • ▪Circlip groove — Width and diameter per DIN 471 / drawingCheck: Groove gauge; first piece and periodic
    • ▪Burrs — None at groove and keyway edgesCheck: Visual; 100%
  3. 3

    Heat treatment

    Quench and temper (or induction hardening of bearing seats) for strength and wear resistance.

    ⚙ Heat-treatment Furnace / Induction HardenerAutomated
    International
    Ipsen, Aichelin
    Mainland China
    To be added
    ⚙ Hardness TesterTest instrumentSemi-automaticManual
    International
    To be added
    Mainland China
    To be added

    Technical control points:

    • ▪Hardness — Per design, e.g. C45 Q&T HB 220–260; induction-hardened seats HRC 50–55; SUS420J2 HRC 40–50Check: Hardness tester; every batch
    • ▪Distortion — Runout ≤ 0.05 mm before grinding (straighten if needed)Check: Runout check; every batch
    • ▪Decarburization — Depth less than grinding allowanceCheck: Metallography; at process qualification and periodic
  4. 4

    Cylindrical grinding

    Bearing seats and the shaft extension are ground to h6 tolerance.

    ⚙ Cylindrical GrinderAutomatedSemi-automatic
    International
    JTEKTGuangzhou, Studer
    Mainland China
    HotmanDongguan, MinjiaGuangzhou, Shanghai Machine Tool Works
    ⚙ CMM, Roundness & Runout GaugesTest instrumentSemi-automaticManual
    International
    MitutoyoDongguan, HexagonGuangzhou, MarpossShenzhen+1 more →
    Mainland China
    To be added

    Technical control points:

    • ▪Diameter and roundness — h6 (Ø8: 0 / −0.009 mm); roundness ≤ 0.003 mmCheck: In-process gauging 100%; air gauge SPC
    • ▪Surface roughness — Ra ≤ 0.4 µm at bearing seatsCheck: Profilometer; sampling
    • ▪Runout between bearing seats — ≤ 0.005–0.01 mmCheck: Runout tester between centres; sampling
  5. 5

    Cleaning, rust protection & inspection

    Parts are cleaned, rust-protected and inspected before packing.

    ⚙ CMM, Roundness & Runout GaugesTest instrumentSemi-automaticManual
    International
    MitutoyoDongguan, HexagonGuangzhou, MarpossShenzhen+1 more →
    Mainland China
    To be added

    Technical control points:

    • ▪Cleanliness — No chips, grinding sludge or oil residue (particles damage bearings)Check: Visual 100%; gravimetric cleanliness per lot if specified
    • ▪Full dimensional report — All drawing characteristics in toleranceCheck: CMM; first article and periodic
    • ▪Rust protection — No rust during storage and transportCheck: Rust-preventive oil / VCI packing; visual at incoming

Incoming inspection & approval tests

  • Material composition and hardnessSpectrometer, HRC / HV
  • Dimensions, runout, cylindricityIncoming inspection
  • Surface roughnessBearing seats and shaft extension
  • Rust protection (salt spray)For carbon-steel shafts as required

Buyer FAQ

Which steel is used for motor shafts?
C45 (45#) steel for general motors, SUS420J2 or SUS416 stainless for corrosion resistance, and alloy steels such as 40Cr where higher strength or induction hardening is needed.
What tolerances are critical?
Bearing seats (typically h6 or k5, ground), run-out between bearing seats and the rotor seat, the knurl or keyway for the rotor, and surface finish (Ra 0.4–0.8 µm on bearing seats).
Turned or ground?
Bearing seats should be ground (centreless or between centres); other diameters can be finish-turned. Knurls for rotor cores are rolled before grinding so that grinding does not affect them.