Eccentric weights used in ERM (Eccentric Rotating Mass) vibration motors are typically made from metals such as steel, brass, or tungsten alloys. The material is selected based on the required vibration force, motor size, weight, and application requirements.
For compact vibration motors requiring high vibration force in a small package, tungsten alloys are often preferred because of their high density.
Historically, both neodymium (NdFeB) and samarium-cobalt (SmCo) magnets have been used in vibration motors. However, neodymium magnets have become the preferred choice for most applications due to their excellent magnetic performance, high energy density, and cost competitiveness.
Compared with samarium-cobalt magnets, NdFeB magnets offer a favorable balance of magnetic strength, compact size, and cost, making them particularly well suited for small, high-performance ERM vibration motors.