Technical requirements for precision parts machining

  • ⑴ Dimensional accuracy. The main surfaces of shaft parts are usually of two types: one is the outer journal that cooperates with the inner ring of the bearing, that is, the support journal, which is used to determine the position of the shaft and support the shaft. The dimensional accuracy requirements are high, usually IT 5 ~ IT7; the other type is the journal that cooperates with various transmission parts, that is, the matching journal, its accuracy is slightly lower, often IT6 ~ IT9.
  • ⑵ Geometry accuracy. Mainly refers to the roundness and cylindricity of important surfaces such as journal surface, outer conical surface, cone hole and so on. The error should generally be limited to the dimensional tolerance range. For precision shafts, the geometric accuracy must be specified separately on the part drawing.
  • ⑶ Mutual position accuracy. Including the inner and outer surfaces, the coaxiality of the important axis, the radial runout of the circle, the perpendicularity of the important end to the axis, and the parallelism between the ends
  • ⑷ Surface roughness. The machining surface of the shaft has roughness requirements, which are generally determined according to the possibility and economy of machining. The supporting journal is usually 0.2 ~ 1.6μm, and the transmission part matching the journal is 0.4 ~ 3.2μm.
  • ⑸ Others. Requirements for heat treatment, chamfering, chamfering and appearance modification.
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