The grinding electrical spindle is a new technology that integrates the machine tool spindle with the spindle motor, emerging in the CNC machine tool field. Alongside linear motor technology and high-speed tool 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's rotor serves directly as the machine tool's spindle, with the spindle unit's housing being the motor base. Together with other components, it achieves an integrated design between the motor and the machine tool's spindle.

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

This transmission structure, where the spindle motor is integrated with the machine tool spindle, makes the spindle component relatively independent from the machine's transmission system and overall structure. As a result, it can be made into a "spindle unit," commonly known as an "electric spindle." Since the electric spindle predominantly uses AC high-frequency motors currently, 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."