The deformation of CNC machine tools is mainly caused by insufficient rigidity or external factors. The following are some methods to prevent the deformation of CNC machine tools:

1. Choose a machine tool with high rigidity: When purchasing a CNC machine tool, choose a machine tool structure with higher rigidity. A machine tool with high rigidity can better resist external and cutting forces and reduce the possibility of deformation.
2. Reasonable basic design of the machine tool: The basic design of the machine tool must fully consider the weight and force distribution of the machine tool to ensure that the machine tool can remain stable during operation. Reasonable foundation design can reduce the vibration and deformation of the machine tool.
3. Regular maintenance: Regular maintenance of machine tools, including cleaning, lubrication and tightening bolts. Keeping the machine tool in good condition can help reduce the occurrence of deformation.
4. Control cutting force and cooling: Reasonably control the cutting force and the use of coolant to avoid the influence of excessive cutting force and temperature on the machine tool. By selecting the appropriate tool, cutting data and cooling method, the deformation of the machine tool can be reduced.
5. Optimize the machining process: In the process of CNC machining, optimize the tool path, cutting parameters and feed speed to reduce the impact on the load and deformation of the machine tool. A reasonable machining strategy can reduce the stress on the machine tool and reduce the possibility of deformation.
6. Regular inspection and adjustment: Regularly check the various parts and key connections of the machine tool to ensure their tightness and precision. For the problems found, adjust and correct them in time to reduce the occurrence of deformation.
7. Stiffness compensation technology: Some advanced CNC machine tools can use stiffness compensation technology to measure deformation through sensors and make feedback adjustments to the control system to achieve more accurate processing. This technology can compensate the deformation of the machine tool to a certain extent and improve the machining accuracy.

It should be noted that the above methods are for reference only, and specific analysis and adjustments should be made according to the type of machine tool and working environment. When encountering larger deformation problems, it is best to consult professional technical support for accurate solutions.