The main differences between 3-axis, 4-axis, and 5-axis CNC machines lie in the number of controllable axes and the machining surfaces that can be covered in a single setup.

Parameter Dimensions	3-Axis CNC	4-axis CNC	5-Axis CNC
Definition of Axis Count	Three linear axes: X, Y, Z The tool moves in a linear direction; during a single setup, it typically faces a single primary plane	Three linear axes + one rotary axis (e.g., A-axis) Linear and rotary axes work in conjunction, allowing multiple sides to be machined in a single setup	Three linear axes + two rotary axes (e.g., A/B) Five-axis simultaneous machining, capable of machining complex surfaces from multiple angles
Typical accuracy	Relatively low (typically ±0.05 mm) Cumulative errors from multiple setups are more pronounced	Moderate (typically ±0.02 mm) Fewer setups	Higher (precision equipment can achieve the ±0.005 mm range) Fewer setups, continuous machining of curved surfaces
Machining efficiency	Lower for complex parts; requires multiple setups and flipping Suitable mainly for 2D/2.5D	Medium to high; multiple surfaces machined in a single setup Cycle times are often significantly shorter compared to 3-axis machining	High; complex surfaces and undercuts require fewer setups Higher machine tool and programming costs
Suitable for	Flat milling, drilling, and slotting Simple 2D/2.5D structural parts	Multi-sided box bodies, cylindrical side profiles Medium-complexity mold cavities	Free-form surfaces such as impellers and propellers Multi-curvature transitions and undercut features

* Accuracy and efficiency are typical industry comparisons; actual results depend on the machine tool, material, and process.