The grinding electrical spindle is a new technology that integrates the machine tool spindle with the motor in the CNC machine tool field. Alongside linear motor technology and high-speed tooling technology, it propels high-speed machining into a new era. The electrical spindle is a set of components, which includes the electrical spindle itself and its accessories: the electrical spindle, high-frequency variable frequency device, oil mist lubricator, cooling unit, built-in encoder, tool changer, etc.

The motor rotor is directly used as the machine tool's spindle, with the spindle unit's housing serving as the motor base. In conjunction with other components, this achieves an integrated design between the motor and the machine tool spindle.

Currently, with the rapid development and maturation of electrical transmission technology (such as variable frequency speed regulation technology and motor vector control technology), the mechanical structure of the high-speed CNC machine tool main transmission system has been greatly simplified, essentially eliminating belt and gear drives. The machine tool spindle is directly driven by an integrated motor, thereby reducing the length of the machine tool's main transmission chain to zero, achieving the "zero transmission" of the machine tool.

This drive structure, where the spindle motor is integrated with the machine tool spindle, allows the spindle component to be relatively independent from the machine's transmission system and overall structure. Consequently, it can be made into a "spindle unit," commonly known as an "electric spindle." As the electric spindle primarily uses AC high-frequency motors at present, it is also referred to as a "high-frequency spindle." Due to the absence of intermediate transmission stages, it is sometimes called a "direct drive spindle."