Bonded Lamination Stack Solutions for Motor Cores
The bonding of electrical steel laminations is a proven solution for achieving high mechanical strength and precise stacking in electric motor cores.
Huaci Technologies specializes in self-bonded lamination cores using thin electrical steels and soft magnetic alloys, offering superior structural integrity and magnetic performance.
Bonding Process
Our process is based on a separated stacking and bonding sequence, enabling optimal control over each stage and ensuring consistent quality for a wide range of motor applications, including torque motors, coreless motors, servo drives, and high-speed electric machines.
In a bonded core, each lamination is coated with a thermosetting epoxy adhesive layer.
Under defined conditions of temperature, pressure, and time, the adhesive layer flows, wets, and chemically crosslinks to form a continuous solid structure that tightly bonds the laminations.
The bonding process not only ensures electrical insulation between laminations but also provides high stiffness, stability, and resistance to vibration and delamination.
The result is a compact core with high stacking factor and reduced eddy current loss.
Material Preparation
We provide silicon steel materials with thicknesses from 0.05 mm to 0.35 mm for precision lamination core manufacturing.
We provide cobalt-iron alloys for applications requiring high magnetic flux density, typically combined with annealing treatment.
We work with various European and Asian steel mills, using their materials in our production.
Bonding Varnish Preparation
We have established the use of several proven bonding varnish (Backlack) types, while continuously expanding and testing new bonding solutions in collaboration with material partners to further enhance lamination performance.
In-house Coating
Each strip is coated in-house with a precisely applied epoxy-based self-bonding Varnish layer to ensure uniform thickness, thermal stability, and strong adhesion.
- Maximum coating width: 450 mm.
- Coating layer thickness: 1.0 – 4.0 µm, tolerance +/- 0.5 µm
- Coil thickness: 0.05 – 0.25 mm
We are likewise equipped with a sheet coating machine for flexible and efficient coating of thin materials.
Cutting and Stacking
Laminations are produced by precision punching or fine blanking, depending on the geometry and thickness.
Tight control of burr height and dimensional tolerance ensures high stacking accuracy.
Laminations are then stacked and aligned within custom fixtures designed to maintain consistent geometry and pressure distribution.
Bonding and Curing
The bonded core is consolidated using a hot-press curing process.
The stack is subjected to a defined combination of temperature, pressure, and dwell time to activate and cure the epoxy bonding layer.
Unlike conventional batch ovens or continuous furnaces, the hot-press approach provides uniform temperature and pressure across the entire stack, ensuring consistent bonding strength and flatness.
Typical curing parameters are within industry norms, adjusted according to the core’s geometry and height.
This process enables:
- Full crosslinking of the adhesive
- Excellent geometric stability
- High stiffness and mechanical strength
Parameter
Conventional Oven Process
Huaci Hot-Press Process
The combination of uniform heating and controlled pressure allows a high stacking factor and consistent flatness across all segments, even with ultra-thin laminations down to 0.05 mm.
Core Performance
- High stacking factor (up to 95%)
- Stable flatness and geometry
- High bonding and shear strength
- Low eddy-current loss and stable magnetic properties
- Excellent thermal endurance
Cooling and Demolding
After curing, the stack is cooled under controlled conditions to minimize residual stress and shape deviation.
The bonded cores are then released from the fixture and proceed to inspection and finishing.
Prototype Bonding and Wire-Cutting Process
For prototyping and early-stage design validation, Huaci also applies an alternative process route.
Individual laminations are first stacked into rectangular or block-shaped assemblies, which are then heated and cured as a single bonded unit.
After curing, the solidified stack is precisely cut to the final rotor or stator geometry using wire electrical discharge machining (EDM) or other precision cutting methods.
This approach allows fast turnaround and high dimensional accuracy for sample production and small batches, enabling customers to validate motor designs before committing to full-scale tooling.
Although the process is less efficient than the standard hot-press route, it provides excellent flexibility and short development lead times, making it ideal for engineering trials, performance evaluation, and prototype verification.
Prototyping Workshop
In-house prototype workshop equipped with advanced laser cutting and medium-speed EDM systems, enabling high-precision processing, flexible prototyping, and fast iteration for new core designs.
- Within 30days prototyping
- Fast delivery
- Custom for your need
Testing
Equipped with a high-precision coordinate measuring machine, it allows precise inspection of product dimensions, shapes, and geometric tolerances. It further enhances measurement accuracy, providing more reliable quality assurance for products.
- High precision
- Multiple types of testing
Magnetic performance testing
Specialized magnetic performance testing equipment enables comprehensive analysis of magnetic properties, promoting improved quality and production efficiency.
lt measures the AC magnetic properties of grain-oriented or non-oriented electrical steel and motor cores across a wide frequency range of 45Hz to 10kHz. lt supports both the Current Method(M.C Method) and Magnetic Field Coil Method (H-Coil Method, optional) for magnetic field strength measurement. This equipment features easy operation, rapid measurement, excellent repeatability, and high reliability
- High precision
- Multiple types of testing
Prototyping Steps
Send us the informations of your project and drawings for further evaluation.
Our engineering team will analyze the project requirements and evaluate feasibility.
Provide quotations based on project requirements, including materials, dimensions, quantity, and processing methods.
Make prototyping according to the requirements, typically using wire cutting and hot pressing methods.
