In the world of electric motors, generators, and transformers, performance, efficiency, and reliability are never accidental. Behind every high-efficiency motor lies a precisely engineered stack of laminations – and at the heart of those laminations is a material that often goes unnoticed: silicon steel.
As a company with over three decades of hands-on experience – founded in 1994 and based in Luoyang Town, Wujin District, Changzhou – Changzhou Huadong Lamination Co., Ltd. has witnessed the evolution of motor core manufacturing. Today, we would like to share some practical industry knowledge on how choosing the right laminations and silicon steel can directly impact motor efficiency, heat generation, and long-term operating costs.
Electric motors operate on alternating current (AC), which creates changing magnetic fields. In a solid iron core, these changing fields induce circulating currents – called eddy currents – that lead to energy loss and heat. The solution is to build the core from thin, insulated laminations.
Standard lamination thicknesses range from 0.50 mm, 0.35 mm down to 0.27 mm or even thinner for high-frequency applications. The thinner the lamination, the lower the eddy current loss – but also the higher the manufacturing cost. For general industrial motors, 0.50 mm laminations offer a good balance. For electric vehicle (EV) traction motors or high-speed spindles, 0.27 mm or 0.20 mm laminations are becoming the new standard.
At Changzhou Huadong, we produce precision-stamped laminations with consistent thickness and burr control, ensuring that stacked cores achieve the tight magnetic circuit performance required by modern motor designs.
Silicon steel contains between 0.5% and 3.5% silicon, which increases electrical resistivity and reduces eddy current losses. The two main types are:
Non-oriented (NO) silicon steel – magnetic properties are uniform in all directions. Used in most rotating machines: motors, generators, compressors.
Grain-oriented (GO) silicon steel – optimized magnetic properties in the rolling direction. Used primarily in transformers and large generators.
For motor laminations, non-oriented silicon steel is the standard choice. Within this category, grades are classified by core loss (W/kg) and magnetic polarization. Common grades include 50W800, 35W440, 27WGP1300, etc. A lower core loss number usually means higher efficiency, but also higher material cost.
Choosing the right grade means balancing efficiency targets with budget. For IE3 or IE4 premium efficiency motors, a mid-to-high grade (e.g., 35W440) is often necessary. For standard IE2 motors, 50W800 may be sufficient.
Even the best silicon steel will perform poorly if laminations are poorly stamped. Excessive burrs reduce the lamination stacking factor (less steel in the same stack height) and can create electrical shorts between laminations, increasing eddy current losses.
Flatness is equally critical. Warped laminations make stacking difficult and can create uneven air gaps in the stator or rotor, leading to vibration, noise, and efficiency loss.
With decades of in-house tooling and stamping experience, Changzhou Huadong maintains strict process controls:
Burr height kept below 0.03 mm (for most applications)
Progressive dies optimized for high-volume consistency
Post-stamping degreasing and heat treatment as required
We also offer custom stamping for motor frames, mechanical parts, and sell silicon steel coils and sheets directly, supporting customers who prefer to do their own stamping or need additional material.
Global regulations (e.g., IE4, IE5 efficiency classes, and China’s GB 18613-2020) are pushing motor manufacturers toward higher efficiency. This drives demand for:
Thinner laminations (0.30 mm and below)
Better magnetic coatings (C5, C6 insulation coatings)
Reduced hysteresis loss through advanced annealing processes
At the same time, NVH (Noise, Vibration, Harshness) has become a key differentiator, especially for appliances, EVs, and HVAC systems. Lamination geometry – slot design, notching patterns, and even magnet pocket shapes – must be optimized not only for electromagnetic performance but also for structural acoustics.
