additive manufacturing questions

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DOMANDE ADDITIVE MANUFACTURING 2023-01-20 As in any other AM technology, in the additive manufacturing by extrusion process of short fiber reinforced polymers, it is very difficult to obtain 3d printed parts with 0% porosity. Among the following sentences, select the CORRECT one: o With a careful selection of the hatch distance, regardless of the other process parameters, the porosity can be minimised and nearly suppressed o With a careful selection of the extrusion temperature, the hatch distance and the layer height, the porosity can be minimised and nearly suppressed o With a careful selection of the hatch distance and the layer height, the porosity can be minimised and nearly suppressed if a “meander” infill pattern is used o The porosity can never be suppressed, with any selection of the printing process parameters, because of the presence of short fibers in the material mixture 2023-07-20 In additive manufacturing by extrusion, the extrusion nozzle temperature is crucial for the success of the process, i.e. for achieving a satisfactory quality of the print. Which of the following sentences is NOT correct? o The nozzle temperature mainly depends on the extruded feedstock, and it must be always set well above the glass transition temperature and close to the melting temperature o When the nozzle temperature is too small, there is a risk of lack of adhesion between the layers o When the nozzle temperature is too high, there is a risk of delamination between the layers, because of thermal distortions o The correct value of the nozzle temperature depends and interacts with many other parameters, including: the transverse feed rate, the nozzle diameter, the layer heigh, the feedstock flow rate o When the nozzle temperature is too small, there is a higher risk of…