Drilling of Metals
The use of ultrashort laser pulses for drilling of metals is highly promising with respect to reduced melt production and recast formation, as well as minimized heat-affected zones. It enables a machining precision far superior to that achieved by longer pulses, the full potential of which, however, can frequently only be reached using low laser fluence levels at the expense of processing speed. Hence, ablation rates are presented versus drilling depth and energy density and discussed in view of an empirical model of laser drilling with respect to their limiting mechanisms. On this basis, processing windows for ideal laser parameters are concluded. With helical drilling being by far the most successful drilling technique using laser pulses in the nano-, pico-, or femtosecond-pulse duration domains, the method is discussed in detail and various technical means are presented for its improvement towards a successful implementation in an industrial environment.
Keywords42.55.Xi 42.65.Re 42.62.Be 42.62.Cf 42.62.Eh 87.50.Hj 07.85.Fv
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