The impact of stator silicon steel sheet bonding and riveting on motor efficiency

Against the backdrop of continuous advancement in the motor manufacturing industry, achieving a balance between structural strength, magnetic performance, noise control, and manufacturing efficiency has become a core challenge for motor design and manufacturing enterprises. Particularly in high-efficiency motors, brushless motors, EV drive systems, and industrial automation, the manufacturing process for stator cores is progressively shifting from a “cost-driven” approach to a “system performance-driven” orientation.

Among numerous critical processes, the connection method for stator laminations holds particular significance. For a long time, traditional riveting has been widely adopted due to its maturity, stability, and controllable costs. However, as motors evolve toward higher efficiency, lower losses, reduced noise, and increased power density, laminations bonding is increasingly becoming the preferred solution for many high-end motors.

This article systematically compares stator laminate bonding with traditional riveting across multiple dimensions—material properties, process principles, performance impacts, manufacturing adaptability, and application scenarios—to assist engineers, technical leads, and procurement decision-makers in making more forward-looking process choices.

I. What Are Stator Silicon Steel Sheets and Their Role in Motors

First, it is essential to clarify the core function of stator silicon steel sheets.

Typically made from cold-rolled non-oriented or oriented silicon steel, these sheets feature high magnetic permeability, low iron loss, and excellent consistency. After stamping, laser cutting, or precision mold processing, the sheets are laminated into the stator core, forming the primary magnetic circuit of the motor.

In other words, stator laminations are not merely structural components; they directly determine:

• Whether the magnetic path flows smoothly
• Whether iron loss levels remain controllable
• Whether motor efficiency stays stable
• Whether noise and vibration can be suppressed

Therefore, the connection method between laminations directly impacts magnetic performance and overall machine reliability.

II. Structural Characteristics and Industry Application Status of Traditional Riveting Processes

1. Basic Principles of Riveting Processes

Traditional riveting techniques secure multiple layers of silicon steel sheets into an integrated structure using rivets, blind rivets, or spot riveting. This method requires no additional adhesive materials, features a clear process flow, and employs mature operational procedures.

Consequently, riveting has long dominated the following sectors:

• Standard industrial motors
• General-purpose asynchronous motors
• Applications with non-extreme noise and iron loss requirements

2. Key Advantages of Traditional Riveting

From a manufacturing perspective, riveting offers distinct benefits:

• Cost-effective: Relatively low material and equipment investment
• High structural strength: Excellent resistance to axial and radial mechanical loads
• Mature process: Well-established supply chain and extensive quality expertise

Thus, riveting remains practical for high-volume, cost-sensitive projects.

3. Limitations of Riveting Processes

However, as demand for high-efficiency motors grows, the limitations of riveting become increasingly apparent:

• Localized stress concentration may induce micro-deformation
• Rivet points disrupt the continuous magnetic path of silicon steel sheets
• Additional mechanical contact points increase iron losses
• Vibration and noise become harder to control

In applications pursuing higher efficiency and lower NVH, traditional riveting increasingly becomes a performance bottleneck.

III. The Emergence and Technical Background of Stator Silicon Steel Sheet Bonding Processes

1. Fundamental Principles of Bonding Processes

Stator silicon steel sheet bonding typically employs specialized motor structural adhesives or insulating adhesives to form uniform, continuous bonding interfaces between laminations. Subsequent pressure or heat curing solidifies the laminated stack into a stable monolithic structure.

Unlike riveting, bonding achieves “surface bonding” rather than “point bonding.”

2. Core Advantages of Bonding Technology

Advancements in materials science and automated equipment have amplified bonding’s advantages:

• Superior magnetic performance: Reduced magnetic circuit interruptions minimize additional iron losses
• Lower Noise: The adhesive layer inherently dampens vibrations
• Lighter Weight: Eliminates the need for additional metal fasteners
• Greater Structural Consistency: Ensures more uniform stress distribution across laminations

Consequently, bonding technology is experiencing rapid adoption in the following sectors:

• Brushless DC Motors (BLDC)
• New Energy Vehicle Drive Motors
• Axial Flux Motors
• High-Speed, High-Power-Density Motors
  

  Riveted-silicon-steel-laminations-in-electric-motor-stator-core

IV. Systematic Comparison Between Bonding and Riveting Processes

1. Comparison from Efficiency and Iron Loss Perspectives

In high-efficiency motors, every watt of loss matters critically.

• Riveting process: Higher risk of localized magnetic saturation
• Bonding process: More continuous magnetic path, lower iron loss

Therefore, bonding solutions offer advantages in IE3, IE4, and even higher efficiency class motors.

2. Comparison from Noise and Vibration Perspectives

• Riveting Structure: Rigid connection facilitates vibration transmission
• Bonding Structure: Adhesive layer absorbs vibrations, delivering superior NVH performance

This explains why bonding is widely adopted in EVs, electric drive axles, and robotic joints.

3. Comparison from Manufacturing and Automation Perspectives

• Traditional riveting: Mature equipment, but limited automation flexibility
• Bonding process: Better suited for automated adhesive application, in-line curing, and consistency control

Long-term, bonding aligns more closely with smart manufacturing trends.

V. Process Selection Recommendations for Different Applications

1. Cost-Sensitive Applications

If project priorities are cost and delivery time with moderate efficiency requirements, traditional riveting remains a reasonable choice.

2. High-Efficiency and High-End Applications

If the objectives are:

• Higher efficiency
• Lower noise
• Greater power density

Then stator laminate bonding offers greater long-term value.

3. New Energy and High-Speed Motors

In EV, electric aviation, robotics, and similar fields, bonding has become the dominant trend.

VI. Future Trends: Processes Coexist in Layered Applications, Not as Substitutes

It is crucial to emphasize that bonding does not entirely replace riveting.

The future scenario is more likely to be:

• Riveting for standardized, mass-produced products
• Bonding for high-performance, high-value-added products

Ultimately, process selection will depend more on application scenarios than on cost alone.

Conclusion: The Optimal Process for High-Efficiency Motors Starts with a System Perspective

Both stator silicon steel sheet bonding and traditional riveting possess irreplaceable value. The true key lies not in determining “which is better,” but in identifying which aligns best with your motor system objectives.

In the era of high-efficiency motors, structural processes are no longer mere manufacturing details—they are integral components of system performance. Only through holistic optimization spanning materials, processes, application scenarios, and system goals can motor manufacturers establish genuinely sustainable technological advantages in fierce global competition.