The theoretical part will be described in the first part of the thesis. In the introduction, thermal cutting processes such as plasma cutting, laser cutting and autogenous cutting, their advantages, disadvantages, etc. are discussed in general. Furthermore, plasma as an aggregate state will be explained and the process of plasma cutting using different protective gases will be described in detail. Different ways of performing plasma cutting are listed and the most important parameters are described in order to obtain the highest quality plasma cutting of aluminum. In addition to all that, we will talk about the automation of plasma cutting, what kind of CNC systems are used, how it is possible to robotize plasma cutting with different sensors and programming software. At the end of the theoretical part, manual plasma devices are described and the plasma device is used in conducting experiment. The experimental part will show what influence the parameters have on the quality of the cutting surface of aluminum EN AW-1050A, 3 mm thick, by plasma cutting with air. The experiment was conducted in such a way that the samples were first cut with different current strengths and cutting speeds, then the samples were processed and a computer analysis was performed to determine the influence of different parameters during plasma cutting. Nine samples were cut, with currents of 20-25 A and cutting speeds of 50-90 cm/min. The analysis measures the angle of inclination of the furrows and the amount of slag produced during cutting. At the end, optimal parameters are taken for different current strengths and cutting speeds, and a conclusion is written according to the obtained results of the experiment.