Describe the accuracy of CNC machining

Recently, I received a message from some netizens asking me whether the accuracy of CNC machining outer diameter can reach 0.001 mm? What we want to say is that your accuracy is calculated according to your inserts, the average machine can control it at 0.01 mm, and the better ones can be controlled at 0.005 mm.

Therefore, it is impossible for the outer diameter of CNC machining to reach this precision of 0.001mm, generally 0.02 mm~0.005 mm. The author has seen that the highest CNC outer diameter processing 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 quality of a product's machined surface. Generally, IT is used to represent the machining accuracy, and IT refers to the dimensional accuracy grade, abbreviated as tolerance. Smaller tolerance classes mean higher workpiece accuracy and greater machining difficulty.

Generally speaking, IT6 is widely used in CNC machining according to the international precision tolerance level, which is widely used in important matching indicators. The surface of IT6 steel has high uniformity requirements, which can ensure high matching performance, stable and reliable use, and the machining center can complete various processes such as drilling, milling, boring, expanding, reaming, and hard tapping. Next, let's talk about the precision of these machining operations.

1. Drilling

Drilling is another important processing procedure of CNC machining centers. Drilling is the basic method of hole processing. Drilling is usually performed on drilling machines and lathes. , and some holes that require high precision can also be completed on the machining center.

The drilling precision is not high, the tolerance level can only reach IT10, and the surface roughness of the workpiece is generally between 12.5-6.3 microns, but after drilling, reaming, reaming and other methods are often used for follow-up Semi-finishing and finishing.

2. Milling

Milling is the most important processing procedure of CNC machining center. It can be said that all machining processes are carried out by milling. Milling is divided into up milling and down milling according to the direction of spindle movement and workpiece feed. The use of rotating multi-blade tools for workpiece cutting is an efficient and commonly used machining method. It is suitable for processing flat, groove, various complex different-surface and curved molds and other special-shaped molds.

The precision tolerance of finishing milling in machining can generally reach IT16-IT8, and the surface roughness of the workpiece processed under this precision is 0.63-5μm.

3. Boring

Boring is usually used to machine the inner diameter part. Enlarging the inner diameter of a hole or cutting a circular profile with a tool, usually used for semi-roughing 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 requirements for grinding accuracy are the highest and the tolerance level is the smallest. Moreover, the tolerance levels of stamping and die casting are very high. Knowing the precision tolerance of each process can make the CNC machining center play the characteristics of high precision.