The manufacturing process of motor stator and rotor lamination cores has a significant impact on the performance of the motor. In the production of motor stator and rotor lamination cores, the direct stacking process and the large rotation process are two different techniques, each with its own characteristics and application scenarios.
01 Direct Stacking Process
The direct stacking process is a more conventional method, where the laminations are stacked directly on top of each other without any angular rotation.
In a progressive die, during the rotor or stator blanking step, the laminations are directly punched into the blanking die cavity. Each lamination is fixed together by the protruding riveting parts on the laminations.
The direct stacking process offers high production efficiency and cost advantages.
02 Large Rotation Process
The large rotation process involves rotating the laminations at a certain angle during stacking to compensate for the cumulative errors caused by uneven material thickness, thereby improving the magnetic performance of the motor.
Since its inception, Yuma Precision has used molds with rotation processes, which can implement a certain angle of rotation stacking inside the mold according to product characteristics and customer requirements. This ensures the perpendicularity, parallelism, and concentricity of the core. In the large rotation process, laminations can be rotated and riveted at large arbitrary angles such as 45°, 60°, 72°, 90°, 120°, and 180°.
The large rotation process is suitable for applications with high precision and performance requirements. It can improve the magnetic performance, dimensional accuracy, and dynamic balance of the core. However, it is relatively more complex, with higher requirements for equipment and technology.
Comparison of Process Principles: Two Error Compensation Approaches
1) Direct Stacking Process: Simple and Straightforward “Stacking Art”
Core Logic:
Individual stamped laminations are stacked at the same orientation and fixed through mechanical interlocking using protrusions and indentations.
Advantages:
Low Cost: No need for complex die structures, reducing equipment investment by about 30%.
High Efficiency: Stamping speed can reach up to 600 strokes per minute, ideal for mass production.
Limitations:
Error Accumulation: Thickness tolerance of silicon steel sheets (±0.02 mm) is directly transferred to the entire core, leading to end face runout exceeding 0.1 mm.
Magnetic Performance Variability: Inconsistent slot permeability results in motor efficiency fluctuations of up to 5%.
2) Large Rotation Process: “Dynamic Error Compensation”
Core Logic:
Each stamped lamination is rotated by a specific angle (45°–180°), allowing thickness deviations to be offset through staggered stacking.
Advantages:
Significantly Improved Precision: Core vertical deviation < 0.02 mm; end face runout < 0.05 mm.
Optimized Magnetic Performance: Slot permeability variation reduced to less than 1%, improving motor efficiency by 2%–3%.
Challenges:
Process Complexity: Requires high-precision rotation systems (servo motors + encoders), increasing equipment cost by about 50%.
Speed Limitation: Due to angle adjustment, stamping speed decreases to 200–400 strokes per minute.
Key Performance Comparison of Motor Core Processes
| Indicator | Direct Stacking Process | Large Rotation Process |
|---|---|---|
| Material Utilization | 95% (minimal waste) | 85%–90% (edge trimming required) |
| Dynamic Balance Accuracy | > 0.1 g·mm/kg | < 0.05 g·mm/kg |
| Core Loss (W/kg @1.5 kHz) | 1.8–2.2 | 1.5–1.8 |
| Die Life | 100 million cycles (standard carbide) | 80 million cycles (requires wear-resistant coating) |
Application Scenarios: Where Each Process Excels
1) Direct Stacking: The “Foundation Choice”
Cost-Sensitive Motors: Home appliances and power tools.
Low-Speed Applications: Industrial fans (<5000 rpm), low-speed electric vehicles (<100 km/h).
Typical Case:
An air conditioner compressor manufacturer adopted direct stacking, reducing the cost per unit by ¥28 and saving ¥1.2 million annually.
2) Large Rotation Process: The “High-Ground Technology”
High-End EV Motors: Used in models like high-performance electric vehicles with speeds up to 20,000 rpm.
Precision Industrial Equipment: Surgical robot joint motors, aerospace servo systems.
Technical Breakthrough:
A leading manufacturer increased motor power density to 12 kW/kg using the large rotation process.
Overall, the main difference between the direct stacking process and the large rotation process lies in the stacking method of the laminations. The choice of the appropriate process depends on the specific requirements of the motor and the manufacturing conditions.
YUMA is a professional motor core manufacturer. Feel free to contact us anytime for inquiries or support.
