ClassA Motor

Raw material

Die-cast Aluminium End Cap

Melting & degassing → High-pressure die casting → Trimming & porosity inspection → CNC machining

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

Process flow

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

  1. 1

    Melting & degassing

    ADC12 ingot is melted and degassed to reduce hydrogen porosity.

    ⚙ Melting Furnace & Degassing UnitSemi-automatic
    International
    To be added
    Mainland China
    To be added

    Technical control points:

    • ▪Melt temperature — About 650–690 °CCheck: Thermocouple; continuous
    • ▪Hydrogen / density index — Density index ≤ 6% after degassingCheck: Reduced-pressure test; every shift
    • ▪Inclusions — Clean melt (fluxing and skimming)Check: K-mould / fracture test; periodic
  2. 2

    High-pressure die casting

    Molten alloy is injected into the steel die at high speed and pressure.

    ⚙ High-pressure Die-casting MachineAutomated
    International
    Bühler, Idra
    Mainland China
    YizumiFoshan, L.K. Machinery

    Technical control points:

    • ▪Die temperature — About 180–250 °C, balanced across the dieCheck: Thermocouples / thermal imaging; continuous
    • ▪Shot profile — Fast-shot speed ≈ 3–6 m/s; intensification ≈ 60–100 MPaCheck: Shot monitoring; 100% of shots
    • ▪Process consistency — Cycle time and biscuit length stableCheck: Machine SPC; continuous
  3. 3

    Trimming & porosity inspection

    Gates and overflows are trimmed; castings are sampled by X-ray for porosity.

    ⚙ X-ray Inspection SystemTest instrumentAutomatedSemi-automatic
    International
    YXLON
    Mainland China
    ZhengyeDongguan, ZhuomaoShenzhen, WahfeiShenzhen

    Technical control points:

    • ▪Porosity in bearing-seat area — ASTM E505 level ≤ 2; no pores > 1 mmCheck: X-ray; first shots each shift and periodic sampling
    • ▪Cold shuts and cracks — NoneCheck: Visual; 100%
  4. 4

    CNC machining

    Bearing seat, spigot and mounting faces are finish-machined.

    ⚙ CNC Machining CentreAutomated
    International
    MazakGuangzhou, OkumaGuangzhou, DMG MORI
    Mainland China
    MinjiaGuangzhou, Haitian Precision
    ⚙ CMM, Roundness & Runout GaugesTest instrumentSemi-automaticManual
    International
    MitutoyoDongguan, HexagonGuangzhou, MarpossShenzhen+1 more →
    Mainland China
    To be added

    Technical control points:

    • ▪Bearing-seat diameter and roundness — Per drawing (typically H7 / J7); roundness ≤ 0.008 mmCheck: Air gauge / CMM; SPC
    • ▪Spigot concentricity — ≤ 0.02 mm to bearing seatCheck: CMM; first article and SPC
    • ▪Exposed porosity — None on bearing seat; ≤ 0.5 mm elsewhereCheck: Visual; 100%

Incoming inspection & approval tests

  • Dimensions and geometric tolerances (bearing seat, spigot)CMM measurement
  • Internal porosity of castingsX-ray inspection
  • Anodizing thickness and salt sprayISO 2360, ISO 9227
  • Material compositionSpectrometer analysis

Buyer FAQ

Which alloy is used for motor end caps?
ADC12 (A383) is the usual choice: good castability and adequate strength. Where the cap must conduct heat from a driver or needs better ductility, A380 or low-iron alloys are used.
How is the bearing seat kept accurate?
The seat is machined after casting, referenced to the spigot so the two are concentric. Typical bearing-seat tolerance is J7 / K7 with roundness within a few microns; porosity in the seat must be checked by X-ray or cut sections.
Is a steel insert needed in the bearing seat?
Aluminium expands about twice as much as steel, so the bearing fit loosens when hot. For high temperature, high load or frequent bearing replacement, a steel insert or a tolerance chosen for hot fit is used.