Stator Core FAQs
①What materials are used for stator and rotor cores?
Stator and rotor cores are typically manufactured from non-oriented electrical steel (NOES) because it provides suitable magnetic properties in rotating electrical machines, including low core loss, appropriate magnetic permeability, and good manufacturability. Material selection depends on motor speed, power density, operating frequency, flux density, thermal conditions, and efficiency targets.
We can work with different electrical steel grades and thicknesses according to customer specifications. Typical considerations include steel grade, lamination thickness, core loss, magnetic flux density, coating system, and mechanical properties. For high-efficiency EV and high-speed motors, thinner electrical steel may be selected to reduce eddy-current losses, although material cost and manufacturing requirements must also be considered.
②How do you choose the right electrical steel for a motor core?
Material selection should be based on the motor's magnetic flux density, operating frequency, core loss target, mechanical requirements, and manufacturing process rather than simply choosing the lowest-loss material.
We evaluate parameters such as specific core loss, magnetic polarization, permeability, lamination thickness, electrical insulation coating, and mechanical strength. For high-speed or high-frequency applications, thinner laminations can help control eddy-current losses. For high-flux-density applications, the magnetic characteristics of the selected grade become particularly important.
The final material should provide an appropriate balance between magnetic performance, manufacturability, cost, and application requirements.
③How does stamping affect stator core performance?
Progressive stamping provides high production efficiency and accurate lamination geometry, but the cutting process can introduce mechanical stress, burrs, and localized changes in the material near the cut edges.
These manufacturing effects can influence magnetic permeability and core loss. Punching clearance, tool condition, material thickness, stamping speed, and burr height therefore need to be controlled carefully. Research on motor-core manufacturing has shown that cutting and subsequent assembly processes can alter the magnetic properties of electrical steel.
Our process control focuses on tooling accuracy, dimensional tolerances, burr control, and inspection to minimize manufacturing variation and maintain consistent lamination quality.
④What is the difference between interlocking, laser welding, and bonding?
These are three different methods for consolidating individual laminations into a rigid motor core.
Interlocking mechanically connects laminations through formed features in the stamping process. It is efficient for mass production but introduces localized mechanical stress and electrical contact between laminations.
Laser welding provides strong mechanical joining with precise weld locations and is suitable where structural strength is important. However, heat input, residual stress, and damage to insulation around the weld can influence magnetic performance. Studies have shown that welding parameters and weld geometry can affect core loss.
Bonding uses an adhesive layer to join laminations while maintaining electrical separation between sheets. It can provide low mechanical stress and favorable magnetic performance, although curing time, adhesive selection, and process control are important.
The appropriate method depends on motor speed, mechanical strength, magnetic performance, production volume, cost, and customer requirements.
⑤Does laser welding increase stator core loss?
Laser welding can affect core loss, primarily because localized heat input, residual stress, microstructural changes, and possible electrical bridging between laminations can alter the magnetic and electrical behavior around the weld.
The actual effect depends strongly on laser power, welding speed, pulse parameters, weld geometry, weld location, number of welds, lamination thickness, and electrical steel grade. Research has demonstrated that optimized pulsed laser welding can balance mechanical strength and magnetic performance, while inappropriate parameters can increase iron loss.
Therefore, laser welding should not simply be optimized for weld strength alone. The process should be developed as a strength-versus-magnetic-performance balance.
⑥When should bonding be used instead of laser welding?
Bonding can be advantageous when the application places a high priority on low magnetic loss, low mechanical stress, dimensional stability, and uniform lamination joining.
Unlike fusion welding, bonding does not introduce a concentrated heat-affected zone into the core. A properly selected adhesive system can also maintain electrical insulation between laminations. However, bonding requires controlled adhesive application, stacking pressure, curing temperature, and curing time.
For high-efficiency motors, EV traction motors, and applications with demanding magnetic-performance requirements, bonding can be considered alongside welding and interlocking rather than treating one joining technology as universally superior.
⑦How do manufacturing processes affect motor core loss?
Motor core loss is influenced not only by the electrical steel itself but also by the manufacturing history of the core.
Important factors include:
Electrical steel grade and thickness
Punching or laser-cutting conditions
Burr height
Mechanical stress
Lamination insulation condition
Stacking method
Interlocking
Laser welding
Adhesive bonding
Press fitting and housing assembly
Operating flux density and frequency
Manufacturing-induced stress and local electrical contact can change magnetic behavior and increase losses. Therefore, achieving low core loss requires control of the entire manufacturing chain, not simply selecting a low-loss steel grade.
⑧How is stator core concentricity controlled?
Concentricity is controlled through a combination of precision stamping, tooling accuracy, automatic stacking, fixture positioning, and dimensional inspection.
Critical features such as the inner diameter, outer diameter, slot geometry, and stack alignment are monitored to minimize eccentricity. During stacking, accurate lamination alignment helps maintain the designed geometry throughout the axial length of the core.
Good concentricity is important because excessive eccentricity can contribute to uneven air gaps, vibration, noise, electromagnetic imbalance, and assembly difficulties.
⑨How do you control burr height during stamping?
Burr control starts with progressive die design and proper punch-to-die clearance. Tool sharpness, stamping parameters, electrical steel thickness, material properties, and die condition all influence the resulting burr.
During production, burr height is monitored through in-process inspection. If burr levels approach the specified limit, tooling maintenance, clearance adjustment, or process optimization may be required.
Controlling burrs is important because excessive burrs can affect stacking accuracy, insulation integrity, dimensional quality, and inter-laminar electrical behavior.
⑩How do you evaluate the magnetic performance of stator cores?
Magnetic performance can be evaluated using several methods depending on the development stage and customer requirements.
For electrical steel materials, Epstein Frame testing can characterize specific core loss and magnetic properties. B-H curves can be used to evaluate the relationship between magnetic field strength and flux density.
For motor-level analysis, finite element analysis (FEA) can simulate magnetic flux distribution, flux density, electromagnetic behavior, and core-loss-related performance. Under inverter excitation, PWM effects, harmonics, operating frequency, and DC bias may also need to be considered.
For core-loss modeling, approaches such as the Steinmetz model and Bertotti loss model can be used depending on the excitation waveform and required modeling accuracy.
⑪Can you manufacture stator and rotor cores according to customer drawings?
Yes. We support custom stator and rotor core manufacturing based on customer drawings, specifications, and technical requirements.
Engineering review can cover:
Lamination geometry
Slot and tooth dimensions
Inner and outer diameters
Lamination thickness
Stack height
Material grade
Stacking method
Welding or bonding requirements
Dimensional tolerances
Inspection requirements
For new projects, the manufacturing process can be reviewed from a DFM perspective to identify potential tooling, stamping, stacking, joining, and inspection considerations before production.
⑫Can you support prototype development through mass production?
Yes. Our production system is designed to support different stages of motor-core development, including prototype, sample validation, small-batch production, and high-volume OEM production.
Prototype and trial production can be used to verify lamination geometry, material selection, stacking method, joining process, dimensional accuracy, and magnetic requirements before mass production.
Once the design and process are approved, production can be scaled through progressive stamping, automatic stacking, laser welding or bonding, standardized inspection, and production planning. This allows the manufacturing process to transition from engineering validation to stable OEM production while maintaining consistent quality.