There are many ways to classify CNC machine tools.
1. Classified according to the CNC motion trajectory of the machine tool, they can be divided into the following types:
Point‑controlled CNC machine tools are those in which, during tool motion, only the accuracy of the tool’s displacement relative to the workpiece is controlled, without regard to the path between two points—for example, CNC drilling machines.
Point‑to‑line control CNC machine tool: Building on point‑to‑point control, it ensures that the tool’s trajectory is a straight line and performs cutting operations during motion.
Contour-controlled CNC machine tools: capable of controlling the motion of two or more coordinate axes (multi-axis linkage), with the tool’s trajectory following a spatial curve.
2. According to the control method of the servo system, it can be classified into the following categories:
Open-loop CNC machine tools: These machines lack position feedback and compensation, resulting in low cost but poor accuracy and stability.
Semi-closed-loop CNC machine tools: They detect and compensate for the position of the servo motor or lead screw, offering high precision and stability, moderate pricing, and the widest range of applications.
Closed-loop CNC machine tools: They detect and compensate for the position of the machine’s moving components, offering high precision and excellent stability, but are difficult to control and come at a higher cost.
3. Classified according to the number of linked coordinate axes, they can be divided into the following types:
2.5-axis CNC machine tool: It can only perform simultaneous motion along the X and Y axes, enabling planar contour machining. Z-axis movement allows for layered machining.
Three-axis CNC machine tools: By coordinating the X, Y, and Z axes, they can perform machining of complex surfaces. Among CNC milling machines, three-axis models are the most common and are widely used in the mechanical manufacturing industry today.
4-axis simultaneous CNC machine tool: In addition to the simultaneous motion of the X, Y, and Z axes, it incorporates rotation about one of these axes.
5-axis CNC machine tool: simultaneous motion along the X, Y, and Z axes, combined with rotation about two of these axes, enables the machining of a wide variety of complex curved surfaces.
4. Classified according to the relative positional relationship between the spindle and the worktable, they can be divided into the following types:
Vertical CNC machine tools: In vertical CNC machines, the spindle is mounted perpendicular to the worktable, enabling operations such as milling, boring, drilling, and tapping. Vertical machining centers typically feature three-axis linkage, allowing for three-dimensional curved-surface milling.
High-end machining centers can also support 4-axis and 5-axis control. Vertical machining centers are suitable for machining parts with small height dimensions.
Horizontal CNC machine tools: In horizontal CNC machines, the spindle is mounted horizontally relative to the worktable. They are typically equipped with rotary axes (rotary tables). These machines are particularly well suited for machining box-type parts, enabling the simultaneous completion of multiple surface and hole‑making operations in a single setup.
The machining center is equipped with a tool magazine on the CNC milling machine, which stores a varying number of cutting and inspection tools. During machining, the program-controlled ATC automatically selects and changes tools, enabling milling, boring, drilling, tapping, and other operations to be performed on a single machine, thus offering a wide range of machining capabilities.

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