10 2 2023

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ADVANCED MANUFACTURING PROCESSES Prof. Strano – Annoni – Demir SURNAME NAME PERSONAL ID Exam – 10th February 2023 Question n. 1 Which of the following statements concerning laser beam transport is WRONG? o An active disc laser can be transmitted in an optical fiber o Diode lasers can be transmitted in transmission fibers with large diameters o A green laser (532 nm) can be transmitted in an optical fiber o A CO2 laser can be transmitted in an optical fiber with some insignificant power loss o An active fiber laser beam can be transmitted with mirrors after the collimation stage Question n. 2 Which of the following laser source/process combinations is NOT FEASIBLE? o Cutting of 2 mm-thick brass plates with a fiber laser o Conduction welding of 0.5 mm-thick steel plates in lap-joint with a diode laser o Keyhole welding of 2 mm-thick stainless steel plates in butt-joint configuration with a CO2 laser o Keyhole welding of 0.5 mm-thick Al-alloy plates in lap-joint configuration with a ms- pulsed Nd:YAG laser o Remote (vaporization) cutting of 1 mm-thick Cu plates with a diode laser Question n. 3 You are carrying out a deep engraving operation with a ns -pulsed active fiber laser source on a tool steel. The operation consists of scanning a square geometry with 2 mm x 2 mm section down to 2 mm depth employing adjacent scan trajectories and multiple passes. After several passes, you observe a reduction of materia l removal rate. Which of the following explanations is a plausible cause? o As more material is removed, the laser beam on the material surface to be processed enlarges (defocuses) due to the caustic propagation o The oxidation reaction during the process reduces the energy input to the material o Steels in general and tool steels in particular cannot be laser…