Influences on hole quality in high precision drilling of steel with ultra-short pulsed laser systems

Abstract

The accuracy of laser drilled holes in metals is limited by a relatively large amount of molten material which is produced when lasers with pulse durations in the range of nanoseconds or longer are used. In general, shortening the pulse duration down to the picosecond or femtosecond regime promises to overcome these problems. In this contribution different influences on hole quality such as energy density, beam quality, and polarization as well as processing strategies for the high precision drilling of steel with ultra-short pulses are presented and discussed. Furthermore, a new method of polarization control is demonstrated by which the hole geometry can significantly be improved and ripples in the surface of the hole walls can be avoided during helical drilling.The accuracy of laser drilled holes in metals is limited by a relatively large amount of molten material which is produced when lasers with pulse durations in the range of nanoseconds or longer are used. In general, shortening the pulse duration down to the picosecond or femtosecond regime promises to overcome these problems. In this contribution different influences on hole quality such as energy density, beam quality, and polarization as well as processing strategies for the high precision drilling of steel with ultra-short pulses are presented and discussed. Furthermore, a new method of polarization control is demonstrated by which the hole geometry can significantly be improved and ripples in the surface of the hole walls can be avoided during helical drilling.