Manufacturing overview · Typical process
NEMA 17 · 1.8° step · 0.3–0.8 N·m holding torque · 34–60 mm length
The highest-volume stepper size in the world, used in 3D printers, CNC and linear modules, lab automation and textile machines. An 8-pole toothed stator drives a 50-tooth rotor built from two laminated cups with an axially magnetized NdFeB ring between them. The radial air gap is only about 0.05 mm, so lamination accuracy, rotor grinding and end-cap concentricity decide torque, noise and consistency.
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Click a model for full specifications and curves.
11 main assembly steps. Each step lists its key equipment and instruments, their main suppliers, and the technical control points.
Stator and rotor laminations are punched in progressive dies, including the small stator teeth and the 50 rotor teeth, and interlocked in-die into stacks. Both rotor cups use the same lamination.
Technical control points:
The stator core is insulated either by epoxy powder coating of the slots and end faces, or by moulded insulating end plates plus slot film. The bore and tooth tips are kept free of coating so the air gap is not reduced.
Technical control points:
The two phases are needle-wound directly onto the 8 stator poles (inner winding). Each phase uses alternate poles with alternating winding direction; wire ends are parked on terminal pins or lead posts.
Technical control points:
Coil ends are soldered to a small rear PCB with a connector, or to lead wires that are then sleeved. Solderable enamelled wire is stripped by the solder heat itself.
Technical control points:
Each wound stator is tested before impregnation so faults can still be repaired.
Technical control points:
The stator is dipped or trickle-impregnated to fix the coil ends and improve heat transfer, then oven-cured. The bore must stay clean.
Technical control points:
Rotor cup, NdFeB ring magnet and the second rotor cup are pressed onto the knurled shaft, with the two cups rotated half a tooth pitch (3.6°) relative to each other.
Technical control points:
The assembled rotor OD is ground to set the ~0.05 mm air gap, then deburred and cleaned. Grinding is done before magnetizing so steel swarf does not stick to the rotor.
Technical control points:
The rotor is magnetized axially in a magnetizing fixture, making one rotor cup a north pole and the other a south pole.
Technical control points:
Bearings are pressed into the end caps, the magnetized rotor is inserted into the stator, a wave washer is fitted and the four through-bolts are tightened. Concentricity relies on the end-cap spigots fitting the stator.
Technical control points:
Every motor is tested electrically and for torque before packing.
Technical control points:
Suppliers are representative examples (international / mainland China), not an exhaustive or endorsed list.
Progressive stamping and in-die interlocking of stator and rotor laminations.
Selection criteria: Tonnage 60–200 t, 200–800 spm, bottom-dead-centre accuracy.
Used in: 1. Lamination stamping & interlocking
Equipment page →Forms and interlocks laminations; determines core accuracy and burr.
Selection criteria: Number of stations, regrind interval, stack-height control method.
Used in: 1. Lamination stamping & interlocking
Equipment page →Verifies dimensions, geometry and runout.
Selection criteria: Measurement uncertainty, probing system.
Used in: 1. Lamination stamping & interlocking, 8. Rotor OD grinding
Equipment page →Coats the slots and end faces of small stator cores with an insulating epoxy layer (fluidized bed or electrostatic), replacing slot liners.
Selection criteria: Coating thickness control, masking of the bore and tooth tips, preheat and cure temperature, cycle time.
Used in: 2. Stator insulation
Equipment page →Inserts slot-liner insulation into stator slots.
Selection criteria: Slot geometry range, cycle time, paper forming method.
Used in: 2. Stator insulation
Equipment page →Winds concentrated coils on inner-rotor stators.
Selection criteria: Spindles, wire-diameter range, tension control, layering accuracy.
Used in: 3. Winding
Equipment page →Solders winding ends to lead wires or a terminal PCB; solderable enamel is stripped by the solder heat.
Selection criteria: Tip temperature stability, solder-wire feed, positioning repeatability, fume extraction.
Used in: 4. Lead termination
Equipment page →Winding resistance, turn-to-turn insulation, hipot and insulation resistance.
Selection criteria: Surge voltage, waveform-comparison algorithm, test cycle time.
Used in: 5. Stator in-process test
Equipment page →Impregnates windings with varnish and cures it for insulation, heat transfer and vibration resistance.
Selection criteria: Vacuum level, heating method (current or oven), temperature profile.
Used in: 6. Impregnation & curing
Equipment page →Rotor-to-shaft and bearing press-fits with force–displacement monitoring.
Selection criteria: Force / displacement resolution, curve evaluation windows.
Used in: 7. Rotor assembly, 10. Final assembly
Equipment page →Applies adhesive for bonding rotor magnets.
Selection criteria: Shot-volume accuracy, 1K / 2K adhesive capability.
Used in: 7. Rotor assembly
Equipment page →Grinds bearing seats and shaft extension to h6 with low roughness.
Selection criteria: Roundness capability, in-process gauging, wheel dressing.
Used in: 8. Rotor OD grinding
Equipment page →Multi-pole magnetizing of rotor magnets, followed by surface-field measurement.
Selection criteria: Stored energy, peak current, fixture pole count and cooling.
Used in: 9. Rotor magnetizing
Equipment page →End-of-line electrical safety tests.
Selection criteria: Output voltage, leakage-current resolution.
Used in: 11. End-of-line test
Equipment page →No-load, load, T–N curve, efficiency, back-EMF and Hall-phase testing.
Selection criteria: Torque range and accuracy, speed range, data acquisition.
Used in: 11. End-of-line test
Equipment page →Main raw materials, purchased components and auxiliary materials. ★ marks items critical to performance or cost. Quantities are typical and vary by model.
| Part | Class | Material | Key specification | Qty | Supply chain / regions | Representative suppliers | Process | Tests |
|---|---|---|---|---|---|---|---|---|
| ★Stator / rotor laminations | Raw material | Non-oriented Electrical Steel | 50W470 or 50W600, 0.5 mm (0.35 mm for high-speed variants) | Per stack length | Mills are outside the Pearl River Delta (Baosteel, Shougang, Ansteel); Pearl River Delta buyers get slit coil from mill service centres and steel distributors in Foshan (Lecong) and Dongguan, or buy finished cores from stamping houses. Ask for the mill certificate with every coil. | WcanFoshan, HongwangFoshan, Fulwealth SteelDongguan+3 more → | Process → | View → |
| ★Winding | Raw material | Enamelled Copper Wire | Solderable polyurethane (class 155) or polyester-imide (class 180), Ø0.2–0.35 mm | 2 phases | The Pearl River Delta has its own enamelled-wire makers in Zhuhai, Foshan, Jiangmen and Huizhou, alongside the big Anhui and Jiangsu producers. Local supply shortens lead time; still audit the thermal class and in-line test records per spool. | RonsenZhuhai, Jingda GuangdongFoshan, Suntek WireJiangmen+2 more → | Process → | View → |
| ★Rotor ring magnet | Raw material | Sintered NdFeB Magnet | Sintered NdFeB ring, axially magnetized, e.g. N35SH; Ni-Cu-Ni or epoxy coating | 1 | Sintered blocks come mainly from Ningbo, Baotou and Ganzhou; Dongguan, Shenzhen and Jiangmen host magnet makers and finishing plants that cut, grind, coat and magnetise to drawing. Specify grade, coating and Hcj at temperature, and ask which plant sinters the block. | Dawa MagnetDongguan, Jiada MagnetDongguan, Courage MagnetDongguan+6 more → | Process → | View → |
| Shaft | Raw material | Motor Shaft | Ø5 mm, stainless (e.g. SUS420J2) or carbon steel; h6 bearing seats; knurled rotor seat, D-cut output | 1 | Dongguan is the Pearl River Delta centre for precision turned and ground shafts, with many CNC-turning and centreless-grinding shops serving the local motor industry. Check the h6 bearing-seat grinding capability and run-out inspection, not just turning. | Sanfeng ShaftsDongguan, LongmingDongguan, DayueDongguan | Process → | View → |
| ★Bearings | Purchased component | Deep-groove Ball Bearing | 625ZZ or 625-2RS, low-noise grade (Z2 / V2 or better) | 2 | Bearing factories are mostly outside the Pearl River Delta (Zhejiang, Liaoning, Henan, Japan); the Pearl River Delta has brand sales offices in Guangzhou and Shenzhen and local makers of miniature bearings in Dongguan and Shenzhen. Buy branded bearings only through authorised channels to avoid counterfeits. | NSKGuangzhou, Fitrun BearingDongguan, Kentie BearingDongguan+6 more → | Process → | View → |
| ★Front / rear end caps | Raw material | Die-cast Aluminium End Cap | ADC12 die-cast aluminium; Ø22 mm pilot; bearing bores and spigots machined in one set-up | 2 | Foshan, Zhuhai and Dongguan have many high-pressure die-casters, from listed auto-parts groups to small motor-cap shops. Ask for X-ray porosity checks at the bearing seat and whether machining is done in-house. | JinjuqiweiFoshan, WencanFoshan, KingrunZhuhai+1 more → | Process → | View → |
| Stator insulation | Auxiliary material | Insulation Bobbin & Slot Liner | Epoxy insulating powder, or PBT / PA66-GF insulating end plates plus polyester slot film | 1 set | Shenzhen and Huizhou have makers of insulation films, sleeving and moulded bobbins; slot liners (DMD, NMN, PET film) are also stocked by Dongguan distributors. Confirm the thermal class matches the insulation system and keep UL file numbers on record. | FuweiHuizhou, WoerShenzhen, JDDShenzhen | Process → | View → |
| Impregnating varnish | Auxiliary material | Impregnating Varnish | Class 155 or higher, compatible with the wire enamel | As required | International varnish makers run Pearl River Delta offices and blending sites (Zhuhai), and Foshan and Zhuhai have domestic insulating-resin producers. Choose varnish and process together — the supplier's process support matters as much as the product. | ELANTASZhuhai, DRDFoshan, ChangxianZhuhai+1 more → | — | View → |
| Leads & connector | Purchased component | Lead Wires & Connectors | 6-pin 2.0 mm connector on a rear PCB with a detachable cable, or UL1007 26 AWG flying leads | 1 set | Shenzhen and Dongguan are a major cluster for wire, harness and connector makers, including offices of international connector brands. Ask for crimp-force monitoring and pull-test records on terminated leads. | MolexShenzhen, WoerShenzhen, XSD CableDongguan+2 more → | Process → | View → |
| Fasteners & small parts | Auxiliary material | Fasteners & Small Parts | 4 × M3 through-bolts, wave washer, spacer | 1 set | Dongguan and Shenzhen have many fastener makers and specialists in retaining rings and wave washers for small motors, so standard parts no longer have to come from Wenzhou or Ningbo. Check plating and hardness certificates per lot. | JinyiDongguan, LiangguDongguan, Lock TechnologyShenzhen+3 more → | Process → | View → |
How each key raw material and purchased component is made: process steps, the equipment and instruments used at each step with their main suppliers, and the technical control points. Click a material to expand.
Steelmaking & vacuum degassing → Hot rolling → Pickling & cold rolling → Continuous annealing → Insulation coating → Testing & slitting
Hot metal is refined in a converter, then RH-degassed to ultra-low carbon; silicon and aluminium are added to the target grade.
Technical control points:
Slabs are reheated and rolled into hot-rolled coils of about 2 mm.
Technical control points:
Scale is removed and the strip is cold-rolled to final gauge (0.50 / 0.35 mm).
Technical control points:
Recrystallization annealing in a protective atmosphere grows grains to the size that minimises core loss.
Technical control points:
A thin inorganic / organic insulation coating is applied and cured to limit interlaminar eddy currents and aid punchability.
Technical control points:
Magnetic properties are tested per coil, then coils are slit to the stamping width.
Technical control points:
Rod drawing → In-line annealing → Enamelling & curing → Lubrication, in-line testing & spooling
8 mm oxygen-free copper rod is drawn through successive diamond dies to the target diameter.
Technical control points:
Resistance annealing restores ductility after drawing.
Technical control points:
Base coat (polyesterimide) and overcoat (polyamide-imide) are applied in many thin passes, each cured in the oven.
Technical control points:
A surface lubricant is applied for winding, diameter and film faults are tested continuously, and wire is spooled.
Technical control points:
Melting & strip casting → Hydrogen decrepitation → Jet milling → Field orientation & pressing → Cold isostatic pressing → Sintering & ageing → Machining → Surface coating → Final inspection
Nd/Pr, Dy/Tb, Fe, B and additives are vacuum-induction melted and cast onto a water-cooled wheel into thin flakes.
Technical control points:
Flakes absorb hydrogen and crack along grain boundaries into coarse powder, followed by dehydrogenation.
Technical control points:
Coarse powder is milled in nitrogen to fine single-crystal particles.
Technical control points:
Powder is aligned in a strong magnetic field and pressed into blocks inside a protective glove box.
Technical control points:
Sealed green blocks are pressed isostatically to raise and even out density.
Technical control points:
Blocks are vacuum-sintered at about 1,050–1,100 °C, then aged in one or two stages to develop coercivity.
Technical control points:
Blocks are sliced, ground or wire-cut into arc segments, then chamfered and cleaned.
Technical control points:
Ni-Cu-Ni electroplating, zinc or epoxy coating protects the magnet from corrosion.
Technical control points:
Magnetic properties, dimensions and appearance are checked per lot.
Technical control points:
Bar cutting → CNC turning & keyway / D-cut → Heat treatment → Cylindrical grinding → Cleaning, rust protection & inspection
Cold-drawn or ground bar stock (SUS420J2 / C45) is cut to length.
Technical control points:
Shoulders, grooves and the shaft extension are turned; the keyway or D-cut is milled.
Technical control points:
Quench and temper (or induction hardening of bearing seats) for strength and wear resistance.
Technical control points:
Bearing seats and the shaft extension are ground to h6 tolerance.
Technical control points:
Parts are cleaned, rust-protected and inspected before packing.
Technical control points:
Ring forging & turning → Heat treatment → Grinding → Superfinishing → Cleaning, assembly, greasing & sealing → Vibration & noise test
GCr15 (52100) bearing steel is forged or turned into ring blanks.
Technical control points:
Through-hardening and tempering to about HRC 60–64.
Technical control points:
Faces, outer diameter, bore and raceways are ground.
Technical control points:
Raceways are superfinished for low roughness and low noise.
Technical control points:
Rings and balls are cleaned, matched for clearance, assembled with the cage, greased and shielded.
Technical control points:
Every bearing is spun and its vibration measured to classify the grade.
Technical control points:
Melting & degassing → High-pressure die casting → Trimming & porosity inspection → CNC machining
ADC12 ingot is melted and degassed to reduce hydrogen porosity.
Technical control points:
Molten alloy is injected into the steel die at high speed and pressure.
Technical control points:
Gates and overflows are trimmed; castings are sampled by X-ray for porosity.
Technical control points:
Bearing seat, spigot and mounting faces are finish-machined.
Technical control points:
Resin drying → Injection moulding → Inspection
PA66+GF pellets are dried before moulding.
Technical control points:
Bobbins (end plates) are moulded, optionally with insert-moulded terminals.
Technical control points:
Dimensions, appearance and flammability conformance are checked.
Technical control points:
Cut, strip & crimp → Crimp verification → Housing insertion & continuity test
Wires are cut and stripped, and terminals crimped automatically.
Technical control points:
Cross-sections and pull tests verify each setup and lot.
Technical control points:
Terminals are inserted into connector housings and the harness is continuity-tested.
Technical control points:
Cold heading & thread rolling → Heat treatment & surface treatment → Optical sorting
Wire is cold-formed into screw blanks and threads are rolled.
Technical control points:
Parts are hardened as required, then zinc-plated or passivated.
Technical control points:
100% sorting removes dimensional and visual defects.
Technical control points:
Materials without a process here (bought-in chemicals, chips and some purchased components) are covered by incoming inspection and approval tests only.
Material-level tests are used for incoming inspection and supplier approval (PPAP / sample approval); motor-level tests for product validation (DV / PV). Conditions and criteria depend on the application and customer specification.
Applies to: Stator / rotor laminations
Applies to: Winding
Applies to: Rotor ring magnet
Applies to: Shaft
Applies to: Bearings
Applies to: Front / rear end caps
Applies to: Stator insulation
Applies to: Impregnating varnish
Applies to: Leads & connector
Applies to: Fasteners & small parts
| Test | Standard / condition |
|---|---|
| High-temperature operation and low-temperature start | IEC 60068-2-1 / -2-2 |
| Temperature cycling / thermal shock | IEC 60068-2-14 |
| Damp heat, steady state (e.g. 85 °C / 85% RH) | IEC 60068-2-78 |
| Salt spray | IEC 60068-2-11 |
| Sinusoidal / random vibration | IEC 60068-2-6 / -2-64 |
| Mechanical shock | IEC 60068-2-27 |
| Temperature-rise test | IEC 60034-1 |
| IP protection rating | IEC 60529 |
| Hipot and insulation resistance | IEC 60034-1 |
| Locked rotor and overload | Per customer specification |
| Endurance test (continuous rated load) | Per customer specification, typically 3,000–20,000 h |
| Noise and vibration | ISO 1680, IEC 60034-14 |
Low-voltage motor without electronics: Assumes a low-voltage motor (up to 48 V) without built-in electronics, exported as a component. An integrated driver or the end use (medical, automotive…) changes the requirements.
Listed alphabetically, not in order of preference. Confirm accreditation scope with each body.
Cost analysis, supplier sourcing and audits, production-line planning and equipment selection, and export certification planning — consulting by a senior motor engineer.
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