Oral questions collection v2

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AMP Theoretical questions GENERAL 1. What are the feasible processes to cut a precise, circular and burr-free micro pocket on zirconia material that looks like the following figure? a) Pure water-jet milling (p=200 bar, nozzle diameter=0.2 µm) b) Micromilling with diamond tools (D=100µm, Vc=200 m/min; fz=0.001 µm/tooth) c) Laser with Femto-second frequency (P=20W, laser spot D=15 µm) d) Plunge EDM with inverse polarity (ton=40 µs, toff=60 µs, I= 50 A peak current, f =10 kHz) e) Plunge EDM with direct polarity (ton=40 µs, toff=60 µs, I= 50 A peak current, f =10 kHz) R. c 2. In the figure, the schematic of a thermal welding process (e.g. laser welding, rotary ultrasonic welding, plasma arc welding, conventional arc welding, resistance welding, etc.) is shown. The heat source is moving from left to right in the direction of the arrow. What is the variable x shown in the diagram? Which welding process is it? Motivate your answer. R. The x variable is the Temperature. The process consists of Plasma arc welding. The reason is that the swirl of the gas does not generate a symmetric distribution of temperature and therefore the temperature profile of points A and B is different WATER JET 1. Explain why the overall efficiency of the Nd:YAG source in Figure 1 is higher than the overall efficiency of the Nd:YAG source in Figure 2. Both sources suffer from the thermal lens phenomenon. Which of the two more? R. Nd:YAG Lamp, which is much more affected by problem of thermal lensing in comparison to laser diode solution. On the other hands the laser diodes are characterized by a narrow laser wavelength of 800-900 nm which is able to produce a good quantic efficiency with Nd:YAG and consequently a much more efficient pumping; this is directly visible by an higher deposit energy (35%…