There can be many reasons for inaccurate dimensions of workpieces processed by CNC machine tools, involving machine tools, cutting tools, technology, programming and other aspects. Here are some of the main reasons why dimensions may be inaccurate:

1. Machine tool problems:

Wear and looseness: The guide rails, screws and other components of CNC machine tools may become worn due to long-term use, or may become loose resulting in inaccurate positioning.

Thermal deformation: CNC machine tools may be affected by heat during long-term high-speed operation and undergo slight thermal deformation, which affects positioning accuracy.

Insufficient rigidity: Insufficient rigidity of CNC machine tools may cause vibration during cutting, affecting machining accuracy.

2. Tool problem:

Tool wear: Using CNC machine tool tools for too long or the hardness of the cutting material exceeds the tool standard may cause tool wear, thereby affecting the processing dimensions.

Tool eccentricity: Incorrect CNC machine tool tool clamping or eccentricity of the tool itself may lead to inaccurate cutting paths.

3. Process issues:

Improper cutting parameters: Improper settings of cutting parameters such as CNC machine tool cutting speed, feed speed, and cutting depth may lead to dimensional out-of-tolerance.

Coolant issues: Insufficient coolant or a faulty cooling system in a CNC machine can cause the workpiece and tool to overheat, which can affect dimensions.

4. Programming questions:

CNC program errors: CNC machine tool programming errors may cause the CNC machine tool to cut along the wrong trajectory, thus affecting the processing size.

Coordinate system error: Due to the CNC machine tool coordinate system error or improper coordinate system switching, the actual position of the workpiece may not match the expected position.

5. Material issues:

Material deformation: During the processing of CNC machine tools, some materials may cause dimensional changes due to internal stress or cutting heat.

Material heterogeneity: The heterogeneity of CNC machine tool materials may lead to different cutting performance in different directions, affecting machining accuracy.

6. Measurement issues:

Inaccurate measuring instruments: If the measuring instruments used by CNC machine tools are inaccurate, it may lead to inaccurate measurement results, which will affect the determination of dimensions.

Solving the problem of inaccurate dimensions of CNC machine tools usually requires systematic analysis, starting from multiple aspects such as CNC machine tool adjustment, tool replacement, process optimization, programming correction, etc., to ensure the accuracy and stability of the entire processing system.