Accuracy of depth of cut in micro milling operations

In any kind of conventional machining operation, dimensional and geometrical accuracy of the machined part cannot be achieved without a precise control of cutting parameters as well as positioning accuracy. Miniaturization of components implies a reduction of all component’s dimensions and involves downscaling of conventional manufacturing technologies. Although in micro manufacturing operations particular precautions are taken, the ratio between tolerances and absolute dimensions increases. However, the absolute required accuracy for the functionality increases, therefore the absolute value of tolerances decreases. Existing machine tools designed for conventional size machining operations are generally unsuited for mechanical micromachining due to a too low positioning accuracy and too high thermal deformations of the machine structure (while static and dynamic stiffness is not generally a problem since the magnitude of the cutting forces involved is reduced), which make mechanical micromachining by use of miniaturized tools troublesome or even impossible. This study deals with the use of a conventional 3 axis vertical milling machine equipped with a high speed attached spindle for micro milling operations, the identification of the main sources of inaccuracy and the solutions adopted for the optimization of machine performances through elimination or compensation of such inaccuracies.