I. Evolution of Motor Cores: Why Segmented Stators Prevail
In traditional motor manufacturing, stator cores are stamped as a single, continuous ring. While mechanically straightforward, single-piece ring laminations restrict automated winding machinery access. Needle winding heads must maneuver through narrow slot openings, capping the maximum Copper Slot Fill Factor at 45%–55%.
By dividing the annular stator geometry into distinct modular segments—such as Single-Tooth (T-Core), Tooth-Yoke Separated, or Multi-Tooth Blocks—manufacturers create an Open Slot Architecture. Coils can be pre-wound directly onto individual teeth using high-speed precision winding or Hairpin copper insertion before final circumferential assembly.
II. Segmented Stator Structural Typologies
- Features: Each tooth is individually stamped with integrated yoke joint.
- Electromagnetic: Fully open winding space, boosting fill factor up to 88%.
- Business: Compact stamping dimensions allow ultra-high nesting density.
- Applications: Humanoid robotics, EV traction motors.
- Features: Teeth and yoke ring are manufactured as separate components.
- Electromagnetic: Teeth are pre-wound and press-fitted into the outer yoke ring.
- Business: Enables asymmetric steel pairing (e.g., 0.1mm steel teeth with standard yoke).
- Applications: High-frequency industrial motors.
- Features: Groups 2–4 teeth into a single modular segment.
- Electromagnetic: Reduces total assembly joints, minimizing flux reluctance.
- Business: Balances higher material yield with lower assembly labor costs.
- Applications: Direct-drive torque motors, wind generators.
| Performance Metric | Single-Piece Ring Stator | Segmented Stator Core | Youyou Company Engineering Standard |
|---|---|---|---|
| Copper Slot Fill Factor | 45% – 55% | 70% – 85%+ | Achieves up to 88% via direct precision pre-winding |
| Material Yield (Strip Utilization) | 40% – 50% | 80% – 90% | Optimized nested stamping reduces scrap by 35% |
| Lamination Stacking Loss | Baseline (rivet/weld shorting) | Minimizable with lap joints | Backlack bonding prevents inter-sheet eddy shorting |
| Scalability (Large Diameters) | Limited by die size & press tonnage | Modular assembly | Infinite diameter expansion via standardized tooling |
III. Electromagnetic Losses & Material Engineering
To achieve high power density at high frequencies (e.g., >1,000 Hz in high-speed motors), core losses (Pcore) must be strictly controlled. Total core loss is expressed by the classical Bertotti equation:
Youyou Company's Backlack Process: We utilize silicon steel pre-coated with B-stage self-bonding epoxy. Stamped segments are stacked and heat-cured under precise pressure profiles. The resulting stack has zero rivets, zero welds, and 100% inter-sheet insulation, lowering high-frequency core loss by 10% to 20% while offering superior structural rigidity and vibration damping.
IV. Precision Joining Geometry & NVH Countermeasures
A primary engineering challenge in segmented stators is the introduction of microscopic joint air gaps (5–15 μm) and tooth pitch variation, which can induce magnetic reluctance and severe NVH (Noise, Vibration, and Harshness).
Mitigation Strategy 1: Staggered Layer Stacking (Lap Joint Overlap)
To eliminate magnetic reluctance caused by joint air gaps, laminations are stacked in an alternating lap-joint configuration. The seam gap of Layer 1 is offset and covered by the continuous steel body of Layer 2, allowing magnetic flux to smoothly "bypass" the gap via adjacent layers.
Mitigation Strategy 2: Sub-Micron Stamping & Radial Potting
- Progressive Die Tolerances: Stamping die tolerances are held within ±0.002 mm (±2 μm) to guarantee uniform tooth pitch.
- Housing Heat Shrink Fit: Assembled segmented stators are radially compressed inside the motor housing via heat shrink fitting or high-thermal resin potting, eliminating joint compliance and neutralizing cogging torque harmonics.
About Youyou Company
As a specialized precision motor core processing manufacturer in China, Youyou Company delivers state-of-the-art 0.10mm–0.20mm ultrathin progressive stamping and advanced Backlack self-bonding lamination solutions. We specialize in Segmented Stator Lamination Stacks (T-Segment teeth), engineered to maximize slot fill factors (up to 88%) for hairpin windings, eliminate interlaminar shorting, and achieve 10%–20% iron loss reduction—delivering maximum torque density and thermal efficiency for global OEMs and Tier-1 suppliers.
Whether you are developing next-generation EV traction motors, humanoid robot joint actuators, high-speed drone propulsion, or semiconductor handling systems, our end-to-end manufacturing capabilities have you covered. Contact our engineering team for 3–5 day rapid prototyping, Backlack thermal bonding trials, DFM strip nesting analysis, and custom soft magnetic alloy (Vacodur 49 / 1J50) core processing.
Ready to Upgrade Your Motor Power Density & Cost Efficiency?
Core Capabilities: Segmented Stator & T-Segment Lamination, 0.10mm Ultrathin Electrical Steel Stamping, Backlack Self-Bonding Technology, Cobalt-Iron Alloy Cores, Hairpin Winding Stators, and Fast-Turn DFM Prototyping.
