When it comes to laborious, monotonous tasks that are typically performed by hand, the polishing of hard materials has got to rank right near the top. Although a really lustrous shine may still require the human touch, scientists have now developed a process for getting a "good enough" shine, using lasers. Instead of removing a fine layer of the material's surface, which is what traditional buffers and polishes do, the lasers melt it.
The system was developed by Germany's Fraunhofer Institute for Laser Technology, in collaboration with the companies Maschinenfabrik Arnold and S&F Systemtechnik. While it could presumably have many applications, it is intended mainly for use on the inside surfaces of metal molds. According to Fraunhofer, such molds are presently polished by hand at a rate of ten minutes per square centimeter.
The main components are a 5-axis gantry system (which holds the mold), and a 3-axis laser, which together allow the laser's beam to access the inside contours of the mold from pretty much every possible angle. The beam is deflected off angled mirrors, which control the rate at which it travels along the surface of the metal. It is able to move as quickly as one meter (3.28 feet) per second, even on small pieces.
Computer-aided manufacturing (CAM) programs, which will likely already be in use by most manufacturers anyway, are used to build a 3D model of the mold. The system can then plan a path for the laser, based on that model.
The laser melts a surface layer just 20 to 100 micrometers deep. The surface tension of the melted material ensures that it will reset evenly. While the end result won't be quite as smooth as what could be achieved by hand, it should be fine for things like glass and tool molds. It will also take as little as one-tenth the amount of time.
Fraunhofer's laser polishing machine should be commercially available soon, and will be unveiled in November at the 2011 EuroMold exhibition in Frankfurt.
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