CNC machining of free- form surfaces is a very  important technology in the machining of precision parts. 

Free-form surface refers to parts with complex curve surface shape, such as automotive partsi aviation parts, medical equipment and SO on.

CNC (Computer Nmerical Control) machining is the proces of using computer -controlled CNC machine tools for processing
 
The key of surface CNC machining is how to transform the complex curve and surface shape into machining path that the machine can understand and execute.
First of all, CAD( Computer - Aided Design) modeling is needed to design the three dimensional geometry of the part.
Then, the CAD model is processed by CAM (Computer - Aided Manufacturing) software to generate the machining path.
The CAM software can automatically generate the cutting path and tool path according to tHe geometry and machining requirements of the part. 

In the CNC machining process of free-form surface, it is necessary to select the appropriate tool and processing parameters.
Due to the complexity of free - form surfaces,it may be necessary to use a specially shaped tool, such ast a ball end tool or a cone tool,
in order to dry cut the surface. 
At the same time, the choice of machining parameters is also very impontant, including cutting speed, feed rate, cutting depth and so on.
Reasonable machining parameters can ensure machining quality and efficiency.
In addition, CNC processing of free cunved surface also needs to consider the process regulations and processing order.

According to the shape and processing requirements of the parts,determine the appropriate process route and processing sequence to maximize the processing efficiency and quality. At the same time, it is also necessary to optimize the tool path in the machining process 
to avoid tool interference and collision and ensure the šafety and stability of the machining pročess.

Therefore, the CNC machining of free- form surface is a complex and key technology which has important application value in the machining of 
precision parts.Though reasonable CAD modeling, CAM processing and processing parameter selection, as well as the as the arrangement of process regulations and processing sequence, efficient accurate and stable free-form surface processing can be realized.