Servo Motor Magnet
The servo motor magnets ensure servo motors to make the control accurate speed and position accuracy, and can convert the voltage signal into torque and speed to drive the control object. The rotor speed of servo motor is controlled by the input signal and can react quickly.
Since the Indramat branch of Rexroth officially launched MAC permanent magnet AC servo motor and drive system at the Hannover trade fair in 1978, this marks that this new generation of AC servo technology has entered into the practical stage. By the middle and late 1980s, each company had a complete series of products. The entire servo market is turning to AC systems. Most of the high-performance electric servo systems use permanent magnet synchronous AC servo motor, and the control driver mostly adopts the full digital position servo system with fast and accurate positioning. There are typical manufacturers such as Siemens, Kollmorgen, Panasonic, Yaskawa, etc.
Due to the accurate function of the servo motor, it has a stringent requirement about working accuracy and high performance, which mainly depends on the quality of Neodymium magnets for servo motors. Due to a wide range of higher magnetic properties, Neodymium magnet makes the servo motors possible with lower weight and smaller size compared to traditional magnetic materials, like Ferrite, Alnico or SmCo magnets.
For servo motor magnets, currently Horizon Magnetics are producing serials of high end grades of Neodymium magnets, like H, SH, UH, EH and AH with following three characteristics:
1.High intrinsic coercivity Hcj: high to >35kOe (>2785 kA/m) which increases magnet demagnetizing resistance and then servo motor working stability
2.Low reversible temperature coefficients: low to α(Br)< -0.1%/ºC and β(Hcj)< -0.5%/ºC which increases magnet temperature stability and ensures servo motors to work with higher stability
3.Low weight loss: low to 2~5mg/cm2 in HAST testing condition: 130ºC, 95% RH, 2.7 ATM, 20 days which increases magnets corrosion resistance to extend life time of servo motors