Introduction to common machining methods

Manufacturing technology is an application technology that transforms raw materials into products.  It is not only the interface and bridge for science and technology to be applied in practice, but also the basis for promoting the development of science and technology. Advanced manufacturing technology is of great significance to the creation of material wealth and the development of science and technology.

All industrially developed countries in the world have advanced creative technologies and huge manufacturing industries. Manufacturing has become the basic pillar industry of industrially developed countries. The material wealth created has reached more than half of the total value of the national economy. Therefore, in order to make the country prosperous and strong, we must vigorously innovate manufacturing technology and vigorously develop modern manufacturing.

Material forming process basis: 

It mainly introduces the technological characteristics of the blank forming method of mechanical parts, the selection of process parameters, the structural manufacturability of various parts blanks, the basic principles of the material selection of parts and the selection of forming methods.

Basic machining process: 

It mainly introduces the basic concepts of machining, basic principles of cutting, cutting machine tools and cutting tools, the basic process of cutting, the basic principles of selecting cutting methods, and the manufacturability of machining structures of parts.

Cutting:

Cutting is the process of using the relative movement of the tool and the workpiece, and the tool removes excess material from the blank or profile in order to obtain parts that meet the requirements of precision and surface roughness.

Cutting is divided into machining and fitter

Fitters and machining 

Fitter: Cutting by hand tools used by workers 

Mechanical processing: using different machine tools (such as lathes, milling machines, planers, grinding machines, drilling machines, etc.) to cut the workpiece

The concept of part surface quality

Part geometry parameters:

Macro geometric parameters: including size, shape, position and other elements

Microscopic geometric parameters: refers to the degree of microscopic surface roughness

Machining accuracy: refers to the degree of the size, shape, position and other parameters consistent with the theoretical parameters of the parts after machining. The smaller the deviation, the higher the machining accuracy, including: 

Dimensional accuracy: the accuracy of dimension parameters of parts 

Shape accuracy: the degree to which the shape of the part is close to the ideal shape 

Position accuracy: The accuracy of actual elements (points, lines, surfaces) on a part relative to the position of the reference

The national standard stipulates that the commonly used precision grades are divided into 20 grades, represented by IT01, IT0, IT1, IT2... IT18 respectively.  The higher the number, the lower the precision.  Among them, IT5-IT13 are commonly used. 

High precision: IT5 and IT6 are usually obtained by grinding 

Medium precision: IT7-IT10 is usually obtained by fine turning, milling and planing 

Low precision: IT11-IT13 are usually obtained by rough turning, milling, planing, drilling and other processing methods.