Describe the accuracy of CNC processing

Recently, I received a message from some netizens asking me if the accuracy of CNC machining outer diameter can reach 0.001 mm? What we want to say is that your accuracy is calculated based on your blade. The general machine tool can be controlled at 0.01 mm, and the better one can be controlled at 0.005 mm.

Therefore, it is impossible for CNC machining to achieve this accuracy of 0.001mm, generally 0.02 mm~0.005 mm. The highest CNC outer diameter processing I have seen can only reach 0.004 mm.

Friends who are familiar with CNC machining centers know that high precision is a feature of machining centers. Accuracy is a mechanical term used to measure the surface quality of a product processed. Generally, IT is used to represent processing accuracy. IT refers to the dimensional accuracy level, referred to as tolerance. Smaller tolerance levels mean higher workpiece accuracy and greater machining difficulty.

Generally speaking, IT6 is classified according to international accuracy tolerance and is widely used in important coordination indicators in CNC processing. The surface of IT6 steel has high uniformity requirements, which can ensure a very high matching performance, and is stable and reliable in use. The machining center can complete a variety of processes such as drilling, milling, boring, expansion, reaming, and hard tapping. Next, let’s talk about the accuracy of these processing processes.

1. Drilling

Drilling is another important processing process in CNC machining centers. Drilling is the basic method of hole processing. Drilling is usually carried out on drilling machines and lathes. Some holes with high accuracy requirements can also be completed on machining centers.

The drilling accuracy is not high, the tolerance level can generally reach IT10, and the surface roughness of the workpiece is generally between 12.5 and 6.3 microns. However, after drilling, reaming and reaming are often used for subsequent semi-finishing and finishing.

2. Milling

Milling is the most important machining process in CNC machining centers . It can be said that all machining processes are carried out through milling. Milling is divided into reverse milling and straight milling according to the direction of spindle movement and workpiece feed. Using rotating multi-edge tools to cut workpieces is an efficient and commonly used processing method. Suitable for processing special shape molds such as planes, grooves, various complex surfaces and curved surface molds.

The precision tolerance of finish milling during processing can generally reach IT16-IT8, and the surface roughness of the workpiece processed at this accuracy is 0.63-5μm.

3. Boring

Boring is usually used to machining inner diameter parts. Use tools to enlarge the hole or cut the inner diameter of the circular profile, which is usually used to go from semi-rough processing to finishing. The machining accuracy tolerance level of steel workpieces can reach IT9-IT7, and the surface roughness is 2.5-0.16 microns.

In the existing processing technology, the highest requirements for grinding accuracy are required and the minimum tolerance level is. Moreover, the tolerance levels of stamping and die-casting are very high. Understanding the accuracy tolerance of each process can allow the CNC machining center to play a high-precision characteristic.