Laser drilling velocity in metals

Abstract

To describe the laser drilling process, a theoretical model that includes expulsion of liquid material is developed. The model allows the calculation of drilling velocity and drilling efficiency as a function of the absorbed intensity. The same quantities were determined experimentally, using Nd-YAG-laser pulses of rectangular shape. Good agreement between measurement and calculation was found in the intensity region where efficient drilling is possible, i.e., where reflection losses and vapor absorption can be neglected. For most metals this region is between 1 and 100 MW/cm2.

Comparison of Laser-Engraved Hole Properties between Cold-Rolled and Laser Additive Manufactured Stainless Steel Sheets

“…According to the heat temperature map published by the British Stainless Steel Association, the yellow to dark brown color seen in the samples indicate temperatures in the range of 57-673 K (30-400 °C) [36]. This agrees well with the previous findings published by the authors [34] where the processing temperature in engraving was measured with thermocouples. There are significant differences between the samples, even after accounting for the darker color and rough surface of the PBF sheets that made it more difficult to estimate where the color began to change.…”

“…The increase is fairly linear. Similar results have been published by von Allmen, who investigated the effect of pulse duration on drilling depth in the microsecond range, and Manninen et al, who investigated the same in the nanosecond range [34,35]. No significant difference can be noticed between the cold-rolled sheets and the PBF sheets.…”

Study of dopant activation in biaxially compressively strained SiGe layers using excimer laser annealing

“…21,22 For the first 7 nm thin amorphous SiGe layer, an optical penetration depth of a À1 $ 6.5 nm was estimated, 23 thus the optical effect to the thermal process by means of the Beer-Lambert law additionally been considered. 24 The numerical model estimates the temperature profiles caused by the first laser pulse. Dopant diffusion below the melting points is not considered in this model.…”

Theoretical and experimental investigation of plasma dynamics for laser-induced machining mechanism

“…Uluslararası Malzeme Sempozyumu Özel Sayısı) S.Çelen [22], [23]. Allmen developed a theoretical model for laser drilling process in 1976 [24]. Knight investigated rapid vaporization concept in 1979.…”