Production of highly precise micro-optic components, such as micro-lens arrays, requires appropriate machining processes and tools to be applied. One such machining process is fast tool servo (FTS) diamond turning. FTS technology is a diamond machining process that applies highly dynamic additional axes to enable production of nonrotation-symmetrical surfaces, such as the aforementioned micro-lens array. In the FTS process, a cutting tool is rapidly moved in and out of a workpiece by FTS module and synchronized with a spindle rotation. For machining control purposes, the required surface shape is decomposed into motion trajectories for different axes, such as C-axis (the spindle), X-axis (x slide), Z-axis (z slide), and W-axis (the FTS tool). According to scientists from the National University of Singapore, the Department of Mechanical Engineering, the motion trajectories for C, Z, and Z axes are not problematic, so that the form error coming from the axes can be ignored. Nevertheless, the FTS module shows high dynamics due to the presence of high-frequency components; it results in form errors in the machined surface and shortens the useful bandwidth of the FTS for precision machining.
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