Shaft parts CNC Turning Requirements

 

Shaft parts are rotating parts, whose length is greater than the diameter, generally consisting of the outer cylindrical surface, conical surface, inner bore and threads of the concentric shaft and the corresponding end face. According to different structural shapes, shaft parts can be divided into optical axis, stepped shaft, hollow shaft and crankshaft.
 
Their accuracy and surface quality are generally more demanding, and their technical requirements are generally based on the main functions and working conditions of the shaft. There are usually the following:
 

(a) Surface roughness

The surface roughness of the shaft diameter that is generally matched with the transmission member is Ra2.5-0.63 μm, and the surface roughness of the bearing shaft that matches the bearing is Ra0.63-0.16 μm.
 

(b) mutual position accuracy

The position accuracy requirements of shaft parts are mainly determined by the position and function of the shaft in the machine. It is usually necessary to ensure the coaxiality of the shaft journal of the assembly transmission to the supporting journal. Otherwise, it will affect the transmission precision of the transmission (gear, etc.) and generate noise. For an axis with normal accuracy, the radial runout of the supporting shaft journal for the matching shaft section is generally 0.01-0.03 mm, and the high-precision shaft (such as the main shaft) is usually 0.001-0.005 mm.
 

(c) Geometrical accuracy

The geometric accuracy of shaft parts mainly refers to the roundness, cylindricity, etc. of the journal, outer cone, Morse taper, etc. Generally, its tolerance should be limited within the range of dimensional tolerances. The surface of the inner and outer circles that require high precision shall be marked on the drawing to allow deviations.
 

(d) Dimensional accuracy

The bearing journals that are used to support the shaft position usually have high dimensional accuracy (IT5~IT7). The precision of the journal size of the assembled transmission is generally lower (IT6~IT9).