Laser-assisted turning of silicon-nitride ceramics

The production of high-precision parts made of silicon nitride ceramic such as roller bearing rings or valves, has required time and cost intensive finish-grinding operations up to now. This situation has resulted in a demand for more efficient machining techniques to be developed and made available to manufacturing industry. A prototype precision lathe with an integrated high power diode for laser-assisted turning has been developed at the Fraunhofer-IPT, which co-operated closely with industrial partners. Continuous heating of the workpiece via laser and the resultant localized loss of material strength, make it possible to machine ceramics using a geometrically defined cutting edge. Complex silicon nitride parts can be manufactured without cooling lubricant, considerably more flexibly and with surface qualities of up to Ra=0.3 µm.