Our ultra-thin-gauge electrical steel laminations already handle the highest rotational speeds recorded. Specified for the greenest hybrid vehicles, the most advanced vacuum cleaners and the fastest cars in the F1 circus, our products put a new spin on innovation.

For application frequencies beyond the standard 50 or 60 Hz, thinner steel may be needed to maintain low losses. Our product range, available with a Suralac^®7000 insulating coating, and now also with the Suralac^®9000 bonding coating, has been optimised for medium to high fundamental frequencies (200 -2500 Hz) and harmonics up to about 25 kHz. For the most extreme applications, we have developed NO 10, the thinnest wide strip electrical steel on the market.
 

Advantages of thin gauge

Thin gauge electrical steels make it possible to make electric motors and generators with very high rotating speed. A standard 2-pole motor connected to the 50 Hz grid rotates at approximately 3000 rpm depending on motor type. Rotating at speeds of 10000 rpm or higher enable much higher power from a motor of the same size as the standard 
frequency motor. Equally these higher rotational speeds facilitate the delivery of a much smaller motor with the same power. The latter is demonstrated in the figure below in which the use of thinner electrical steel allows motors to be smaller, using less steel, and still obtaining the same power and efficiency.

Space and weight can be saved using thin gauge steels. 80 kW motors, with the same efficiency, optimised for different speeds using a standard grade compared to two different Hi-Lite™ grades.

High frequency losses

To maintain high motor efficiency at high speeds, the steel used in the motor needs to have low magnetic losses at high frequencies. At these frequencies the total losses are dominated by eddy current losses, which are proportional to the strip thickness squared and inversely proportional to the electric resistivity of the strip. Thus, thin gauge, in combination with high silicon and aluminium content in the steel (increases resistivity), are needed for low loss at high frequencies. Hi-Lite™ grades are made using two different chemical compositions, resulting in two groups of grades called “N” and “H”.

The importance of strength

The rotors of internal permanent magnet motors, typically used in electric vehicles, have thin “bridges” of steel keeping the magnets in the rotor in place. The thinner these “bridges” can be made, the higher the torque of the motor. In combination with high rotational speeds these “bridges” are subject to high mechanical stresses. Thus, the strength of the steel in the rotor is of great importance for the performance and durability of high speed internal permanent magnet motors.

Hi-Lite™ grades have high minimum levels of strength in combination with low loss. This is mainly obtained via the mechanism called “solid solution strengthening” coming from the high amounts of silicon and aluminium added to the steels. 

Our Hi-Lite™ grades significantly reduces losses at higher frequencies compared to normal gauge electrical steels. Opening a whole new array of design and application possibilities for your business. Another focus area is our HP-grades (High Permeability) for applications where improved permeability is of importance. A recent addition to our product portfolio are our grades with guaranteed mechanical strength.

For more detailed data on our Hi-Lite™ grades please contact Surahammars Bruk at sales@sura.se