Requirements of Spindle

(1) The spindle should rotate along with high degree of accuracy. The accuracy of rotation is computed by the axial and radial run out of the spindle nose. The radial and axial run out of the spindle nose should not exceed specific permissible values. These values depend upon the needed machining accuracy. The rotational accuracy is influenced mainly by the stiffness and accuracy of the spindle bearings particularly by the bearing that is located at the front end.

(2) The spindle unit must comprise high dynamic stiffness and damping.

(3) The spindle bearing have to be selected in such a way that the initial accuracy of the unit should be maintained throughout the service life of the machine tool.

(4) Spindle unit should have fixture that provides quick and reliable centering and clamping of the cutting tool or workpiece.

(5) The spindle unit must comprise high static stiffness. Maximum accuracy is influenced by the bending, axial also torsional stiffness.

(6) The wear resistance of mating surface should be as high as possible.

(7) Deformation of the spindle because of heat transmitted to it by workpiece, cutting tool, bearings etc. should be as low as possible. Otherwise it will influence the accuracy of the machining accuracy.