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Usually monocrystalline diamonds tools are applied due to their unsurpassed cutting edge properties. New cutting tool material developments have shown that it is possible to produce tools made of nano-polycrystalline diamonds with cutting edges equivalent to monocrystalline diamonds. In nano-polycrystalline diamonds ultra-fine grains of a few tens of nanometers are firmly and directly bonded together creating an unisotropic structure. The properties of this material are described to be isotropic, harder and tougher than those of the monocrystalline diamonds, which are unisotropic. This publication will present machining results from the newest investigations of the process potential of this new polycrystalline cutting material.
In order to provide a baseline with which to characterize the cutting material cutting experiments on different conventional machinable materials like Cooper or Aluminum are performed. The results provide information on the roughness and the topography of the surface focusing on the comparison to the results while machining with monocrystalline diamond. Furthermore, the cutting material is tested in machining steel with ultrasonic assistance with a focus on tool life time and surface roughness. An outlook on the machinability of other materials will be given.
Free form surfaces are now commonly used components in optics applications and can be widely found in fields such as ophthalmics, car illumination and head-up display systems and laser optics. The machining of free form optics on a 3-axis diamond turning machines is made possible with the use of tool servo machining which synchronises either or both the axial and radial motions of the tool and surface positions (X and Z axes) to the angular position of the spindle (C axis).
However, the machining of surfaces with non-zero gradient at the surface centre is particularly troublesome because the tool is still subject to a relatively large amplitude motion when reaching the central area of the surface. As a result, a small tool offset in either X (radial) or Y (height) creates a particular central signature that can be readily identified, measured and subsequently corrected by the machine operator.
In this paper, we report on a method to optimise the tool offset (X axis) in the particular case of non-zero central gradient and illustrate our discussion with simulation and measurement results.
The measurement and generation of orbital angular momentum using an optical geometric transformation
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