Laser processing machine
Laser processing machines are machine tools that process materials with the help of a high-energy laser beam . The area of application includes a large number of manufacturing processes such as cutting , changing material properties or primary shaping .
Laser processing machines are used for cutting, engraving, structuring, welding, heat treatment (surface hardening) and coating as well as for volume-building processes ( rapid prototyping , selective sintering ). As a force-free machining process, in contrast to mechanical machining processes, heavy clamping devices can usually be dispensed with. Light part pickups are sufficient to hold the workpieces in position. Typical designs are portal, C-column and side-column machines.
The spectrum of machinable materials includes all metals, plastics, glass, ceramics, stone, wood, textiles and paper. In the case of combustible materials, ignition must be prevented by using inert gases and only briefly injecting energy. Today, CO 2 lasers or Nd: YAG lasers are mostly used as laser beam sources . For surface hardening, welding and powder application also come diode laser used. Lithographic micromachining is also performed with excimer lasers.
The laser beams are guided through fiber optic cables (Nd: YAG laser, some with diode laser) or via deflection mirrors (CO 2 laser, excimer laser) to the processing optics, which focus the laser beam and thus generate the required power densities.
Due to their compactness, diode lasers can also be guided directly over the workpiece - their poor beam quality often does not allow coupling into a fiber optic cable or transport over long distances.
Systems with CO 2 lasers mostly consist of a fixed laser resonator and so-called flying optics. The beam emerging from the resonator has a more or less pronounced beam waist that changes the focal length and thus the focus position on the workpiece when the optics are moving. To compensate for this and to reduce the thermal load on the deflecting mirrors, the beam is often widened with a mirror telescope.
The beam guidance between the resonator (laser beam source) and the focusing optics is implemented by mirrors that may be water-cooled. The mirrors are gold- or molybdenum-coated and consist of monocrystalline silicon or pure copper. In systems that are to cut metal two- or three-dimensionally in all degrees of freedom, phase-rotating mirrors are arranged between the resonator and telescope: arrangements of 1, 2 or 4 such mirrors ensure that the linearly polarized laser beam is circularly polarized in order to ensure the cutting quality in all directions the same - otherwise the polarization-dependent absorption in the cutting gap would lead to a direction-dependent edge quality and cutting performance.
With Nd: YAG and sometimes with diode lasers, the beam can be guided to the focusing optics via fiber optic cables.
The German company Trumpf is a large manufacturer of laser processing machines .