Those who know CNC machining centers 640 know that high precision is a major feature of machining centers. Machining accuracy refers to the fineness of the produced product, a mechanical term used to evaluate the processed surface. Machining accuracy is generally expressed by IT, IT refers to the level of determining the degree of accuracy of the size, referred to as tolerance. The smaller the tolerance level, the higher the accuracy of the workpiece, and the greater the processing difficulty.
Generally speaking, according to the classification of international precision tolerance grades, IT6 is widely used in important matching indexes for machining. IT6 indicates that the mating surface has a higher uniformity requirement, which can ensure a fairly high mating property, and is stable and reliable in use. The machining center can complete various processes such as drilling, milling, boring, expansion, reaming, and rigid tapping. So how is the accuracy of these processing procedures divided and defined?
Milling
Milling is the most important processing procedure of the machining center. It can be said that all the machining processes of the machining center are carried out by milling. Milling is divided into up milling and down milling according to the direction of spindle movement and workpiece feed. Cutting the workpiece by using a rotating multi-edged tool is an efficient and common machining method for machining centers. It is suitable for processing special profiles such as planes, grooves, various complex different surfaces and curved molds.
The precision tolerance level of finishing milling in milling is generally up to IT16-IT8, and the surface roughness of the workpiece under this tolerance precision processing standard is 0.63-5μm.
Drilling
Drilling is another important processing procedure of machining center. Drilling is a basic method of hole processing. Drilling is often performed on drilling machines and lathes. Some high precision requirements can also be completed by machining centers.
The machining accuracy of drilling is low, the tolerance level generally can only reach IT10, and the surface roughness of the workpiece is generally 12.5-6.3μm. However, after drilling is completed, reaming and reaming are often used for subsequent semi-finishing and finishing.
Boring
Boring is generally used for the processing of inner diameter parts. It is a machining process that uses a tool to expand the hole or cut the inner diameter of a circular contour, and is generally used in semi-rough machining to finishing. The tolerance level of the boring accuracy of steel workpieces can reach IT9-IT7, and the surface roughness is 2.5-0.16μm.
In the current machining process, the precision of grinding is the highest and the tolerance level is the lowest. The tolerance level of stamping and die-casting is high. Only by understanding the precision tolerance of each process can we let the CNC machining center play its high-precision characteristics.
