The lathe spindle refers to the axis on the machine tool that drives the rotation of the workpiece or tool. Usually composed of spindle components, bearings, and transmission components (gears or pulleys). In machines, it is mainly used to support transmission components such as gears and pulleys, transmit motion and torque, such as machine tool spindles; Some are used to clamp workpieces, such as mandrels. Except for machine tools such as planers and pullers whose main motion is linear, most machine tools have spindle components. 45 steel is commonly used for shaft components, with high-precision shafts available in 40Cr, bearing steel GCr15, spring steel 65Mn, or ductile iron available;

Standard Precision Requirements for Lathe Spindles (GB4020-83)

(1) The axial displacement of the spindle is 0.01mm.

(2) The bearing surface of the spindle shoulder has a runout of 0.02mm.

(3) The radial runout of the spindle centering journal is 0.01mm.

(4) Radial runout of the spindle cone hole axis: ① 0.01mm near the spindle end face; ② The length measured at 300mm from the spindle end face is 0.02mm.

(5) The parallelism of the spindle axis with respect to the movement trajectory of the bed saddle: ① 0.02mm in length measured within 300mm of the vertical plane (only allowed to deviate upwards); ② The length measured within 300mm of the horizontal plane is 0.015mm (only allowed to deviate forward).