Electric vehicles, energy-efficient industrial motors, fans, pumps, compressors and transformers all have one thing in common: they depend on electrical steel. As India pushes electric mobility, higher motor efficiency classes and a much larger power grid, demand for precisely slit electrical steel is growing quickly.
Electrical steel is also one of the most demanding materials to process. Its magnetic performance can be damaged by poor slitting, and its thin gauges and coatings leave little room for error. This article explains the two main types of electrical steel, why slitting quality matters so much, and what to look for in a line for electrical steel slitting.
CRNO vs CRGO: The Two Types of Electrical Steel
CRNO (Cold Rolled Non-Oriented)
CRNO has magnetic properties that are similar in all directions within the sheet. That makes it suitable for rotating machines, where the magnetic field turns with the rotor. It is used for stator and rotor laminations in EV traction motors, industrial motors, generators, compressors and household appliance motors.
CRGO (Cold Rolled Grain Oriented)
CRGO has its grains aligned in the rolling direction, which gives very low loss when magnetised along that direction. It is used mainly for transformer cores. We covered the current CRGO supply situation in our article on CRGO core cutting for transformer makers.
Why Demand for Electrical Steel Slitting Is Rising
- Electric vehicles: Every EV traction motor uses a stack of thin CRNO laminations, and two-wheeler, three-wheeler and car EV production in India continues to expand.
- Motor efficiency standards: Higher efficiency classes for industrial motors require better grades of electrical steel and tighter lamination quality.
- Power grid build-out: India’s plan to more than double transformer capacity by 2032 is driving CRGO demand.
- Appliances and HVAC: Inverter air conditioners, BLDC fans and efficient compressors all use electrical steel laminations.
Lamination stampers and core makers usually buy wide master coils and need them slit to the exact width of their stamping dies or core designs. That is where the slitting line comes in.
Why Slitting Quality Matters for Electrical Steel
Burr damages insulation
Electrical steel carries a thin insulating coating. Burr on the slit edge can cut through the coating of neighbouring laminations when they are stacked, creating electrical contact between layers and increasing eddy current losses.
Edge strain affects magnetic properties
The shearing action at the slit edge creates a narrow zone of plastic deformation. Clean cuts with sharp knives and correct clearance keep this zone small. Blunt knives or poor setup widen it and increase core loss.
Width tolerance affects stamping
Strip width must match the stamping die closely. Too wide and it will not feed; too narrow and the lamination will be out of specification.
Camber affects feeding
High-speed lamination presses need straight strip. Camber causes misfeeds and die damage. Our guide on camber and burr defects explains the root causes.
Surface and coating protection
Scratches, dents or coating damage during slitting and recoiling reduce the value of an expensive material.
What to Look for in an Electrical Steel Slitting Line
Precision slitter head
Rigid arbors with minimal runout and accurate knife positioning are essential for thin gauges. Knife clearance and overlap must be settable in small increments.
High-quality tooling
Tool steel or carbide knives with a fine edge finish, precision-ground spacers and good stripper rings help achieve low burr. Plan for a regular regrinding schedule.
Gentle strip handling
Rubber-coated or polished rolls, controlled pass-line height and smooth transitions reduce surface damage and edge strain.
Accurate tension control
A good separator and tension unit gives evenly wound coils without telescoping and without overstressing narrow strips.
Narrow strip capability
Motor lamination stampers often need narrow widths. Check the minimum strip width and the maximum number of cuts the line can handle.
Clean recoiling and packing
Interleaving paper and proper coil wrapping protect the coated surface in storage and transit.
For most electrical steel applications, a light gauge slitting line built for thin, coated material is the right starting point.
Practical Tips for Processing Electrical Steel
- Set knife clearance for the actual thickness and grade rather than using a general rule for mild steel.
- Measure burr regularly during a run, not only on the first coil.
- Keep tooling dedicated to electrical steel where possible, so knives are not dulled by harder or dirtier materials.
- Control humidity in storage to protect coated coils before and after slitting.
- Record coil traceability, since customers in EV and motor supply chains increasingly require it.
How Valgo Supports Electrical Steel Processors
Valgo Machinery builds slitting lines and transformer core cutting machines for processors of CRNO and CRGO steel. Each line is configured around the customer’s grades, thickness range, strip widths and output. Get in touch to discuss your electrical steel slitting requirement.
Frequently Asked Questions
What is the difference between CRNO and CRGO steel?
CRNO has similar magnetic properties in all directions and is used for rotating machines such as motors. CRGO has grains aligned in one direction and is used mainly for transformer cores.
Why is burr a problem in electrical steel slitting?
Burr can damage the insulating coating between stacked laminations, which increases eddy current losses and reduces motor or transformer efficiency.
Which electrical steel is used in EV motors?
EV traction motors use thin grades of CRNO electrical steel for their stator and rotor laminations.
Can a standard slitting line process electrical steel?
A line intended for electrical steel needs precise knife setting, low arbor runout, good tooling and gentle handling. Discuss the specific grades with your machine supplier before buying.
How often should slitting knives be reground for electrical steel?
It depends on the grade, thickness and tonnage processed. Monitor burr height during production and regrind before it exceeds the customer’s specification.