Special Design for Rotor Magnet - Stepper Motor Magnet – Horizon

Stepper motor magnet means a Neodymium ring magnet with high remanence and coercivity assembled between two stacks of Silicon-Iron (FeSi) laminations to work as a rotor of the brushless stepper motor. With the continuous development of mechanization, electrification and production process automation, various types of special motors emerge. The working principle of stepping motors is generally similar to that of ordinary asynchronous motors and DC motors, but they have their own characteristics in performance, structure, production process and so on, and they are mostly used in automatic control process.

The stepper motors using rare earth Neodymium magnet have some advantages like high torque at low speed & small size, quick positioning, fast start/stop, low working speed, low cost, etc, in spite of disadvantages compared with servo motors like low efficiency, low accuracy, high noise, high resonance, high heating, etc. Therefore the stepper motors are suitable for the application with requirement about low speed, short distance, small angle, fast start and stop, low mechanical connection rigidity and acceptance of low vibration, noise, heating and accuracy, for example, tufting machines, wafer testing machines, packaging machines, photo printing equipments, laser cutting machines, medical peristaltic pumps, and so on. There are typical manufacturers of stepper motors such as Shinano Kenshi, Autonics, Sonceboz, AMCI, Phytron, ElectroCraft, etc.

Stepper motor magnet is one of the most important components to ensure stepper motors to work with good performance and cost. When choosing stepper motor Neodymium magnets, the stepper motor manufacturers should consider following three factors at least:

1. Low cost: Unlike servo motors, the stepper motor is inexpensive, so it’s important to find the cost effective Neodymium magnet. The Neodymium magnets are available with a wide range of magnetic grades and cost. Although the UH, EH and AH grades of Neodymium magnets can work at high temperature exceeding 180C degrees, they contain specially expensive heavy rare earth, Dy (Dysprosium) or Tb (Terbium) and then are too expensive to fit the low cost option.

2. Good quality: N grade of Neodymium magnets are much cheaper but their maximum working temperature is lower than 80C degrees, and not high enough to ensure motor working performance. Normally SH, H or M grades of Neodymium magnets are the best options for stepper motors.

3. Quality supplier: The quality for the same grade may vary between different magnet suppliers. Horizon Magnetics are familiar with stepper motors and understand what quality aspects of the stepper motor magnets are needed to control for stepper motors, such as angle deviation, consistency of magnetic properties, etc.