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In this work the various problems concerning the CO2 laser cutting of copper sheet are reported. In the first part of this research all the thermophysical parameters that regulate the process dynamics have been individualized and than the weight of each parameter has been evaluated numerically, even if only approximately.
The surface absorption value of copper at room temperature and near the melting point and the size order of laser power that is necessary to cause a gradual raising of the workpiece temperature from room to melting temperature have been estimated. Than, the size order of the cutting speed at which a sheet of a known thickness can be cut has been evaluated. The analysis of all this problems, joined to the process dynamics and state of the art seems to confirm the validity of the current thesis on the impossibility of copper cutting by CO2 laser. 1,2,8,9,10,12÷31 In the second part of the work the experimental results relating to the first ever tests on 0.2÷4.0 mm thick copper sheet cutting by 2 KW CO2 laser are reported. These first interesting results have been obtained thanks to the possibility of making overlapped layers of cupric oxide CuO, mixed with a small quantity of cuprous oxide Cu20 grown under laser beam irradiation (CuO and Cu20, together, allow the laser cutting to be carried out). We have also seen that the percentage absorption of laser radiation at 10.6 micron does not increase in the presence of just cuprous oxide while, when the experimental conditions allow it the growth of cupric oxide increases the absorption value to around 52+58 per cent, giving rise to the loop process with three variable quantities (temperature-oxide-absorption) that has been the winning clue of cutting process. The work speeds turned out to be significant and various micrographic sections, performed on the work pieces have shown that the laser cutting quality is quite good.
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