What is the Highest Machining Accuracy of Machine Tools?

Importance of accuracy of the machine tool

The accuracy of the machine tool determines the degree of refinement of the processed product to a large extent. If we use the traditional machine tool and the CNC machine tool to operate at the same level of technology, the accuracy of the CNC machine tool will be higher. After all, there are computers that control more than humans. The control is more accurate and precise. And if the machine tool is aging, machine parts may have problems, and the electrical system fails, the accuracy of the machine tool will be reduced.

Nowadays, most manufacturers are using CNC machine tools, and there are many factors influencing the machining accuracy of CNC machine tools. Statistics show that more than 65.7% of CNC machine tools do not fully meet the accuracy standards when installed, and more than 90% of CNC machine tools are in a state of inaccuracy during work, and there are errors in dynamic accuracy. This determines the importance of monitoring the working status of the machine tool, and it plays an important role in ensuring the accuracy of the machine tool.

Some people even think that the accuracy of machine tools is related to the national military level, representing the manufacturing level of a country, and can almost rise to the strategic level.

CNC lathe turning machine and milling machine, as the most common machine tools, what is the range of accuracy that can be achieved?


The workpiece rotates, and the turning tool performs cutting processing of linear or curved movement in the plane. Turning is generally performed on a lathe to process the inner and outer cylindrical surfaces, end surfaces, conical surfaces, forming surfaces and threads of the workpiece.

The turning precision is generally IT8-IT7, and the surface roughness is 1.6~0.8μm.

  • Rough turning strives to use large cutting depth and large feed to improve turning efficiency without reducing the cutting speed, but the machining accuracy can only reach IT11, and the surface roughness is Rα20~10μm.
  • For semi-finishing and finishing turning, try to use high speed and small feed and cutting depth, the machining accuracy can reach IT10~IT7, and the surface roughness is Rα10~0.16μm.
  • High-speed precision turning of non-ferrous metal parts with a finely-refined diamond turning tool on a high-precision lathe can make the machining accuracy reach IT7~IT5, and the surface roughness is Rα0.04~0.01μm. This kind of turning is called “mirror turning”.


Milling refers to the use of rotating multi-edge tools to cut workpieces, and is a highly efficient processing method. It is suitable for processing planes, grooves, various forming surfaces (such as splines, gears and threads), and special shapes of molds. According to the same or opposite direction of the main movement speed and workpiece feed direction during milling, it is divided into down milling and up milling.

The machining accuracy of milling is generally IT8~IT7, and the surface roughness is 6.3~1.6μm.

  • The machining accuracy during rough milling is IT11~IT13, and the surface roughness is 5~20μm.
  • The machining accuracy of semi-finishing milling is IT8~IT11, and the surface roughness is 2.5~10μm.
  • The machining accuracy of finishing milling is IT16~IT8, and the surface roughness is 0.63~5μm.

Write a Comment