ClassA Motor

Auxiliary material

Fasteners & Small Parts

Cold heading & thread rolling → Heat treatment & surface treatment → Optical sorting

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

Process flow

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

  1. 1

    Cold heading & thread rolling

    Wire is cold-formed into screw blanks and threads are rolled.

    ⚙ Cold Heading & Thread Rolling MachinesAutomated
    International
    National Machinery, Sacma
    Mainland China
    To be added

    Technical control points:

    • ▪Head dimensions — Per ISO standard (e.g. ISO 4762 / 7045)Check: Gauges; SPC
    • ▪Thread — 6g toleranceCheck: Go / no-go thread gauge; every lot
  2. 2

    Heat treatment & surface treatment

    Parts are hardened as required, then zinc-plated or passivated.

    ⚙ 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:

    • ▪Property class / hardness — e.g. 8.8 (HRC 22–32) or stainless A2-70 (ISO 898-1 / ISO 3506)Check: Hardness tester; every lot
    • ▪Coating thickness — Zinc 5–8 µm with passivation (ISO 4042)Check: XRF; every lot
    • ▪Hydrogen-embrittlement relief — Bake at 190–220 °C ≥ 4 h within 4 h of plating for parts ≥ 320 HVCheck: Oven record; every lot
  3. 3

    Optical sorting

    100% sorting removes dimensional and visual defects.

    ⚙ Optical Sorting MachineAutomated
    International
    To be added
    Mainland China
    To be added

    Technical control points:

    • ▪Mixed parts — 0 ppmCheck: Optical sorter; 100%
    • ▪Thread and head defects — ≤ 10 ppm outgoingCheck: Optical sorter; 100%

Incoming inspection & approval tests

  • Salt sprayISO 9227
  • Hardness and torqueISO 898-1

Buyer FAQ

Which fasteners do small motors use?
Machine screws for end caps and mounting, self-tapping screws in plastic, retaining rings (circlips) and wave washers for bearing preload, and keys or pins on the shaft.
Why do wave washers matter?
They apply a light axial preload to the bearings, which removes axial play, reduces noise and takes up thermal expansion. Specify the load at working height.
Which coatings are used?
Zinc plating with trivalent passivation (RoHS), zinc-nickel or zinc flake for higher salt-spray resistance, and stainless steel where plating is not acceptable.