Small-scale machining centers have been rapidly developed, and there have been interchangeable spindle box machining centers, which are equipped with multiple multi-axis spindle boxes equipped with tools that can be automatically replaced, and can perform multi-hole machining of workpieces at the same time.

This form of multi-process centralized machining has also been extended to other types of CNC machine tools, such as turning centers. It is equipped with multiple automatic tool changers on a CNC lathe and can control more than three coordinates. In addition to turning, the spindle can be stopped Or indexing, and the process of milling, drilling, reaming and tapping by tool rotation is suitable for processing complex rotating body parts.

Machining centers are divided into vertical and horizontal types according to the arrangement of the spindle. The horizontal cnc machining center generally has an indexing turntable or a numerical control turntable, which can process all sides of the workpiece; it can also be used for joint movement of multiple coordinates in order to process complex spatial curved surfaces. Vertical machining centers generally do not have a turntable, only for top surface machining. In addition, there are composite machining centers with vertical and horizontal spindles, and vertical and horizontal adjustable machining centers with spindles that can be adjusted to horizontal or vertical axes. They can process five faces of the workpiece.

The automatic tool changer of the machining center is composed of a tool magazine and tool change mechanism for storing tools. There are many types of tool magazines, the common ones are disc type and chain type. The capacity of the chain knife stock is larger.

Tool change mechanism exchanges tools between the machine tool spindle and the tool magazine, the common one is the manipulator; there are also those without the manipulator and the spindle directly exchanges the tool with the tool magazine, called the armless tool changer.