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ADVANCED MANUFACTURING PROCESSES Prof. Strano – Annoni – Demir SURNAME NAME PERSONAL ID Exam – 20th January 2023 Question n. 1 Which of the following statements is WRONG concerning the active media of industrial laser sources? o Liquid state media are not preferable since they can provide visible wavelengths o Solid state media can be in the form of a rod or a fiber doped with ions or elements o Gaseous state media can be in the form of molecules o Semiconductor media such as diodes can provide direct conversion from electricity to photons o The active media type influences also the final electrical (wall -plug) efficiency of the laser Question n. 2 Consider the laser cutting operation of a 1 mm-thick mild steel plate. Which of the following could be considered to improve the process productivity? o Employ Ar as the cutting gas to better protect the material surface o Place the focal point 5 mm above the material surface for a larger spot size on the material surface o Remove the process gas to operate in the vaporization cutting regime o Polish the material surface to improve surface quality o Reduce the focal length of the focusing lens Question n. 3 You plan to employ the stationary extended heat source model to estimate the weld depth during a single-pulse laser keyhole welding operation. Which of the following statements is WRONG concerning your model? o The model is not adequate since it does not consider phase transformation o The model is not adequate since the optical absorptivity is constant over time o The model is not adequate since the heat source is not planar o The model is not adequate since it does not estimate temperature change along the thickness o The model is not adequate since it does not estimate temperature change along the surface plane…