## 3 Results of Studies of AE Signals
### Results of Studies of AE Signals When Processed Using Concentrated Energy Flows  
At first glance, it seems that blade processing and concentrated energy flow processing technologies do not have many common properties. However, similar properties can be found in the behavior of AE signal parameters in these types of processing. Figure 13 shows records of changes in AE signal parameters during the processing of the HG20 (W94K6) alloy on the CUT30P WEDM machine (Figure 6). Figure 13a shows how the amplitude 1/3 octave spectrum is distorted from the moment the cutting begins until it approaches the moment the wire electrode breaks: the amplitudes at high frequencies decrease, and at low frequencies, they increase. In recordings of the AE signal (Figure 13b) in two frequency ranges, this trend continues. The amplitudes change unevenly, but the noted trend remains. Figure 13c shows how the RMS amplitudes of the AE signal components, the records of which are shown in Figure 13b, and the discrete values of K\({}_{\text{f}}\), which are averaged over short periods, change as the moment of electrode break approaches. If we compare the data in Figure 13 with the blade machining results shown in Figures 9-12, the trends in the behavior of the AE signal parameters will be similar in many respects. The central coincidence of the properties of AE signals is that the deterioration of the technological process conditions causes an increase in the K\({}_{\text{f}}\) parameter, which is the ratio of RMS amplitudes in the low and high frequency ranges. For blade processing, the deterioration of conditions was expressed in increased wear of the cutting tool, and for WEDM processing, as an increase in the concentration of erosion products in the interelectrode gap. Another method of processing materials with concentrated energy flows is the technology of electron beam doping in a vacuum chamber. Works [49,50,55] described the use of wire waveguides for recording AE signals (Figure 5) from the area of irradiation of workpiece surfaces with electron beams. Figure 14 shows the results of an experiment with irradiation of an M20 alloy [54] with pulses of increasing charging voltage of an electron gun. As the charging voltage increases, the power of the electronic pulse supplied to the processing area, the duration of which was 4 us, increases. Figure 14a shows the amplitude  
Figure 12: Examples of recording RMS amplitudes of AE signals in the ranges of 2–8 kHz and 23–33 kHz and the K\({}_{\text{f}}\) parameter during grinding on the first pass (**a**) and the 29 th pass (**b**); view of the surface with traces of burns after treatment (**c**). spectra of the AE signals that accompanied the effects of these pulses on the M20 alloy [54] at charging voltages of 16 kV and 22 kV. The graphs in Figure 14b show the changes in the RMS values of the amplitudes of the AE signals at high and low frequencies during the time, including the moment of the peak value of the AE amplitude at high frequencies. The values of the charging voltage are marked horizontally, which, in this case, is proportional to the heat flow power density. In the case of electron beam processing with different charging voltages, it is impossible to talk about the deterioration of processing conditions. We can say that the thermal power acting on the surface of the workpiece changed. With a decrease in the power of the heat flow and the preservation of the irradiated area, we can talk about a decrease in the power density q\({}_{s}\) (the ratio of the power of the heat flow to the area of exposure) and a reduction in the corresponding productivity of the irradiation process. If, conditionally, a drop in power density is taken as a deterioration of conditions (a decrease in productivity), then in the case of electron beam processing, the trend mentioned above of a reduction in K\({}_{\rm f}\) will continue with a deterioration in the conditions of the technological process. A similar change in K\({}_{\rm f}\) occurs when the workpiece surface is exposed to laser pulses.