A team of researchers at Kaunas University of Technology (KTU), Lithuania have developed a novel approach to precision grinding of hard and brittle materials achieving unparalleled efficiency of this process. By experimenting with tungsten carbide they created an innovative technology for shaping the extremely strong and yet easily breakable material into a desirable form.
High tech industry demand for high-performance optical components—from glass lenses for consumer products such as digital cameras to high-end products like medical systems—is increasing exponentially. In precision glass moulding, that allows the production of optical components from glass without grinding and polishing, hard and high-temperature resistant mould materials, such as tungsten carbide, are being used.
“Machining tungsten carbide in order to make the cylindrical details used in the moulding of optical elements is challenging. First, it is a very hard material, so any tool contacting with it is being worn almost instantly, second, if the tool is inserted too deep into the surface of tungsten carbide, the latter breaks. In order to be able to machine the hard and brittle material, it needs to reach plastic deformation state, when it can be shaped and formed without breaking,” explains Gytautas Balevičius, a researcher of KTU Institute of Mechatronics.
One of the ways to achieve the plastic deformation of the workpiece is the ultrasonic excitation of the tool. In other words—the tool starts vibrating and the vibration is transferred to the workpiece. The higher the frequency of excitation, the better the chances of achieving the state of plastic deformation of the material being ground. In a laboratory environment, it is possible to achieve the excitation frequency needed for plastic deformation using nano-scratching but so far it has been impossible to reach these frequencies in industrial conditions.