The Pursuit of Peak Efficiency: Why Our Plant is Transitioning to Backlack (Self-Bonding) Lamination Technology

As a veteran in the motor core manufacturing industry, I know that in the race for motor efficiency, every micron of thickness and every Newton of bonding force matters. Today, Backlack (Self-Bonding Coating) technology has shifted from a "luxury niche" to a mandatory "entry ticket" for high-performance EV motors.

"Backlack is expensive—is it truly worth it?" This is the question I hear most from our clients. Today, I’ll break down the core technical and commercial logic of this technology from the perspective of the factory floor.

I. The Factory Advantage: Why Engineers Demand Backlack

1. "Damage-Free" Physical Performance

  • Stress Elimination: Conventional clinching or interlocking creates significant local mechanical stress, degrading magnetic permeability. Backlack is a "stress-free" connection. Our tests show that core loss is reduced by 10% - 15% compared to traditional methods using the same steel grade.
  • Superior Insulation: While welding destroys interlaminar insulation and creates short-circuit paths, Backlack forms a dense, continuous insulation layer (approx. 2-6 µm) after curing, completely eliminating interlaminar eddy currents.

2. High-Speed Structural Integrity

Once cured, the core becomes a monolithic block with shearing strengths often exceeding 20 MPa. This ensures that rotor laminations remain perfectly aligned even at extreme speeds of 20,000+ RPM. Furthermore, the full-surface bond provides natural protection against moisture and salt spray corrosion.

Impact of Clinching Vs Backlack On Motor Magnetic Permeability

II. Factory Secrets: Mastering the "Three Devilish Details"

1. The "Pressure Balancing Act" During Curing

During the heating phase, the resin passes through a "glass transition" state where it flows like honey. If the pressure is too low, the bond fails; if too high, resin squeeze-out leads to dimensional inaccuracies. We utilize closed-loop servo-hydraulic controls to maintain thickness tolerances within ±0.05 mm.

2. Zero Tolerance for Burrs

In Backlack stacking, burrs are lethal. Because of the full-surface contact, even a 0.03mm burr can decrease the bonding area and dilute strength. We sharpen our progressive dies 1.5x more frequently than standard tools to keep burr heights strictly below 0.01 mm.

3. Thermal Uniformity Management

For large-diameter stators, temperature gradients between the ID and OD can cause uneven curing. Our facility employs Induction Heating combined with Mold Heat Transfer to ensure the entire core reaches the curing window simultaneously.

Interlaminar Bonding Reliability For Thin Gauge 0.1Mm Electrical Steel Automated Induction Heating Vs Oven Curing For Motor Core Bonding Backlack Vs Clinching Eddy Current Loss Comparison In Ev Motors Difference In Interlaminar Insulation Resistance Between Welded and Bonded Cores Dimensional Stability of Bonded Motor Cores Under 20000Rpm Centrifugal Force Environmental Resistance of Bonded Iron Cores In Salt Spray and Humidity Gap Filling and Sealing Properties of Self Bonding Lamination Resins Impact of Mechanical Interlocking Stress On Magnetic Permeability of Electrical Steel Improving Motor Stacking Factor Space Factor With Self Bonding Technology Magnetic Flux Density Distribution In Clinching Vs Backlack Motor Cores Optimal Curing Temperature and Pressure Cycles For Eb 549 Bonding Progressive Die Maintenance For Self Bonding Coated Electrical Steel Reducing Motor Acoustic Noise and Vibration Nvh With Backlack Bonding Roi of Eliminating Secondary Od Grinding Via Backlack Lamination Rotor Dynamics and Balancing of Backlack Bonded Motor Stacks Self Bonding Lamination Technology For Ultra High Speed Motor Rotors Shear Strength of Self Bonding Lamination At High Operating Temperatures Stiffness and Mechanical Damping of Backlack Stacked Laminations Thickness Tolerance Control In Backlack Lamination Stacking Process Total Cost of Ownership Analysis Backlack Vs Traditional Clinching

III. The Economic Reality: Is Backlack Actually More Expensive?

Feature Clinching / Welding Backlack Self-Bonding
Secondary Processing Requires OD grinding (due to welding distortion) No grinding required; achieves final dimensions out of the mold
Assembly Handling Prone to "spring-back"; requires extra fixtures Solid monolithic structure; handles like solid metal
Space Factor (Stacking Factor) Lower (approx. 95-96%) Ultra-high (can exceed 98%)
NVH Performance Requires additional acoustic damping Native noise reduction via high structural damping

Conclusion: While the raw material cost is higher, the total system cost is often lower because you eliminate secondary grinding, reduce motor size, and achieve superior power density.

IV. Advice for Motor Designers

  • Account for Expansion: Curing adds a slight thickness to the coating. Always verify "nominal stack height" with us during the design phase.
  • Optimize Positioning Holes: Ensure at least three symmetrical alignment holes are included for high-precision curing fixtures.
  • Coating Compatibility: Brands like EB 549 or Remisol have different curing profiles. Consult with us early to ensure compatibility with our production lines.

Looking for a manufacturing partner?

We provide full-link solutions from material selection (JFE, Baosteel) to final thermal curing.

Request a Technical Consultation

Have specific dimensions? Contact our technical team for the "Backlack Process Specification Manual" or to request a sample of our latest high-speed bonded rotors.

About Youyou Technology

Youyou Technology Co., Ltd. specializes in the manufacture of Self-bonding precision cores made of various soft magnetic materials, including Self-bonding silicon steel, ultra-thin silicon steel, and Self-bonding specialty soft magnetic alloys. We utilize advanced manufacturing processes for precision magnetic components, providing advanced solutions for soft magnetic cores used in key power components such as high-performance motors, high-speed motors, medium-frequency transformers, and reactors.

The company Self-bonding precision core products currently include a range of silicon steel cores with strip thicknesses of 0.05mm(ST-050), 0.1mm(10JNEX900/ST-100), 0.15mm, 0.2mm(20JNEH1200/20HX1200/ B20AV1200/20CS1200HF), and 0.35mm(35JNE210/35JNE230/ B35A250-Z/35CS230HF), as well as specialty soft magnetic alloy cores including VACODUR 49 and 1J22 and 1J50.

Quality Control for Lamination Bonding Stacks

As an stator and rotor lamination bonding stack manufacturer in China, we strictly inspect the raw materials used to make the laminations.

Technicians use measuring tools such as calipers, micrometers, and meters to verify the dimensions of the laminated stack.

Visual inspections are performed to detect any surface defects, scratches, dents, or other imperfections that may affect the performance or appearance of the laminated stack.

Because disc motor lamination stacks are usually made of magnetic materials such as steel, it is critical to test magnetic properties such as permeability, coercivity, and saturation magnetization.

Quality Control For Adhesive Rotor and Stator Laminations

Other Motor Laminations Assembly Process

Stator Winding Process

The stator winding is a fundamental component of the electric motor and plays a key role in the conversion of electrical energy into mechanical energy. Essentially, it consists of coils that, when energized, create a rotating magnetic field that drives the motor. The precision and quality of the stator winding directly affects the efficiency, torque, and overall performance of the motor.

We offer a comprehensive range of stator winding services to meet a wide range of motor types and applications. Whether you are looking for a solution for a small project or a large industrial motor, our expertise guarantees optimal performance and lifespan.

Motor Laminations Assembly Stator Winding Process

Epoxy powder coating for motor cores

Epoxy powder coating technology involves applying a dry powder which then cures under heat to form a solid protective layer. It ensures that the motor core has greater resistance to corrosion, wear and environmental factors. In addition to protection, epoxy powder coating also improves the thermal efficiency of the motor, ensuring optimal heat dissipation during operation.

We have mastered this technology to provide top-notch epoxy powder coating services for motor cores. Our state-of-the-art equipment, combined with the expertise of our team, ensures a perfect application, improving the life and performance of the motor.

Motor Laminations Assembly Epoxy Powder Coating For Motor Cores

Injection Molding of Motor Lamination Stacks

Injection molding insulation for motor stators is a specialized process used to create an insulation layer to protect the stator's windings.

This technology involves injecting a thermosetting resin or thermoplastic material into a mold cavity, which is then cured or cooled to form a solid insulation layer.

The injection molding process allows for precise and uniform control of the thickness of the insulation layer, guaranteeing optimal electrical insulation performance. The insulation layer prevents electrical short circuits, reduces energy losses, and improves the overall performance and reliability of the motor stator.

Motor Laminations Assembly Injection Molding of Motor Lamination Stacks

Electrophoretic coating/deposition technology for motor lamination stacks

In motor applications in harsh environments, the laminations of the stator core are susceptible to rust. To combat this problem, electrophoretic deposition coating is essential. This process applies a protective layer with a thickness of 0.01mm to 0.025mm to the laminate.

Leverage our expertise in stator corrosion protection to add the best rust protection to your design.

Electrophoretic Coating Deposition Technology For Motor Lamination Stacks

FAQS

What is the most cost-effective core material for high-volume production?

For high-volume production, silicon steel (0.20-0.35mm) remains the most cost-effective option. It offers an excellent balance of performance, manufacturability, and cost. For applications requiring better high-frequency performance, ultra-thin silicon steel (0.10-0.15mm) provides improved efficiency with only a moderate cost increase. Advanced composite laminations can also reduce total manufacturing cost through simplified assembly processes.

How do I choose between amorphous metals and nanocrystalline cores?

The choice depends on your specific requirements: Amorphous metals offer the lowest core losses (70-90% lower than silicon steel) and are ideal for applications where efficiency is paramount. Nanocrystalline cores provide a better combination of high permeability and low losses, along with superior temperature stability and mechanical properties. Generally, choose amorphous metals for maximum efficiency at high frequencies, and nanocrystalline cores when you need balanced performance across a wider range of operating conditions.

Are cobalt-iron alloys worth the premium cost for EV applications?

For premium EV applications where power density and efficiency are critical, cobalt-iron alloys like Vacodur 49 can provide significant advantages. The 2-3% efficiency gain and 20-30% size reduction can justify the higher material cost in performance-oriented vehicles. However, for mass-market EVs, advanced silicon steel grades often provide better overall value. We recommend conducting a total lifecycle cost analysis including efficiency gains, battery size reduction potential, and thermal management savings.

What manufacturing considerations are different for advanced core materials?

Advanced materials often require specialized manufacturing approaches: Laser cutting instead of stamping to prevent stress-induced magnetic degradation, specific heat treatment protocols with controlled atmospheres, compatible insulation systems that withstand higher temperatures, and modified stacking/bonding techniques. It's essential to involve material suppliers early in the design process to optimize both material selection and manufacturing approach.

What thicknesses are there for motor lamination steel? 0.1MM?

The thickness of motor core lamination steel grades includes 0.05/0.10/0.15/0.20/0.25/0.35/0.5MM and so on. From large steel mills in Japan and China. There are ordinary silicon steel and 0.065 high silicon silicon steel. There are low iron loss and high magnetic permeability silicon steel. The stock grades are rich and everything is available..

What manufacturing processes are currently used for motor lamination cores?

In addition to stamping and laser cutting, wire etching, roll forming, powder metallurgy and other processes can also be used. The secondary processes of motor laminations include glue lamination, electrophoresis, insulation coating, winding, annealing, etc.

How to order motor laminations?

You can send us your information, such as design drawings, material grades, etc., by email. We can make orders for our motor cores no matter how big or small, even if it is 1 piece.

How long does it usually take you to deliver the core laminations?

Our motor laminate lead times vary based on a number of factors, including order size and complexity. Typically, our laminate prototype lead times are 7-20 days. Volume production times for rotor and stator core stacks are 6 to 8 weeks or longer.

Can you design a motor laminate stack for us?

Yes, we offer OEM and ODM services. We have extensive experience in understanding motor core development.

What is the advantages of bonding vs welding on rotor and stator?

The concept of rotor stator bonding means using a roll coat process that applies an insulating adhesive bonding agent to the motor lamination sheets after punching or laser cutting. The laminations are then put into a stacking fixture under pressure and heated a second time to complete the cure cycle. Bonding eliminates the need for a rivet joints or welding of the magnetic cores, which in turn reduces interlaminar loss. The bonded cores show optimal thermal conductivity, no hum noise, and do not breathe at temperature changes.

Can glue bonding withstand high temperatures?

Absolutely. The glue bonding technology we use is designed to withstand high temperatures. The adhesives we use are heat resistant and maintain bond integrity even in extreme temperature conditions, which makes them ideal for high-performance motor applications.

What is glue dot bonding technology and how does it work?

Glue dot bonding involves applying small dots of glue to the laminates, which are then bonded together under pressure and heat. This method provides a precise and uniform bond, ensuring optimal motor performance.

What is the difference between self-bonding and traditional bonding?

Self-bonding refers to the integration of the bonding material into the laminate itself, allowing the bonding to occur naturally during the manufacturing process without the need for additional adhesives. This allows for a seamless and long-lasting bond.

Can bonded laminates be used for segmented stators in electric motors?

Yes, bonded laminations can be used for segmented stators, with precise bonding between the segments to create a unified stator assembly. We have mature experience in this area. Welcome to contact our customer servic.

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Start stator and rotor lamination Self-adhesive Cores stack Now!

Looking for a reliable stator and rotor lamination Self-adhesive Cores stack Manufacturer from China? Look no further! Contact us today for cutting-edge solutions and quality stator laminations that meet your specifications.

Contact our technical team now to obtain the self-adhesive silicon steel lamination proofing solution and start your journey of high-efficiency motor innovation!

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