# Computer-Aided Analysis of the Formation of the Deformation Zone in the Burnishing Process
## 3 Three-Dimensional Deformation Zone Imaging  
The measurement results presented in the study were obtained using the Talyrond 365 roundness measurement station (with Ultra Roundness 5.17 control program) [35]. It is equipped with a self-levelling, aerostatic measuring table, facilitating the measurement process. The equipment enables comprehensive, three-dimensional analysis of the shape of cylindrical surfaces with a resolution of 1.3 nm. During measurement, points located on the circumference of the cylindrical surface are collected in the form of a digital point cloud in the number of 3600 or 18,000 points (optionally) per 1 revolution of the table. The positioning resolution of the measuring table is 0.02 degrees. The methodology used in the research consisted of performing a series of axially shifted measurements, allowing the creation of a three-dimensional image of the deformation zone area for the entire circumference of the analysed cylindrical surfaces. This makes it possible to perform three-dimensional imaging of changes in the shape of the obtained burnished surfaces depending on the method and technological parameters of the burnishing treatment performed (Figure 13). As a result, thanks to the use of computer technology, i.e., digital processing of a cloud of measurement points, it became possible to analyse the shape of the unevenness formation zone in selected cross-sections perpendicular to the axis of the burnished cylindrical surface. It was possible to recreate the shape of the material wave forming in front of the burnishing tool in the direction of the main burnishing movement. The computer-aided measurement allowed for the analysis of changes occurring in the geometry of the pressed surface, as well as the initial turned surface after the preceding machining (Figures 13 and 14). Figure 11: Computer-aided analysis of the dependence of the contact surface area of the burnishing tool on the burnishing process parameters: (**a**) ball R = 5 mm, (**b**) disc R\({}_{\text{k}}\) = 5 mm. Figure 12: Disc burnishing (R\({}_{\text{k}}\) = 10 mm, F = 2.5 kN)—numerical analysis of the digitally processed area of contact between the tool and the burnished material. The analysis of the data obtained as a result of the measurements made it possible to draw conclusions regarding the nature of changes taking place in the surface layer of the processed material. The burnishing process leads to plastic deformation of the material and, as a result, to the formation of a wave of piled-up material both in the circumferential  
Figure 14: Ball burnished surfaces—the three-dimensional image of the burnishing zone: (**a**) (R = 5 mm, F = 2.75 kN, \(f_{\text{turn}}\) = 0.410 mm/rev, \(f_{\text{burn}}\) = 0.102 mm/rev), (**b**) (R = 5 mm, F = 2.75 kN, \(f_{\text{turn}}\) = 0.102 mm/rev, \(f_{\text{burn}}\) = 0.186 mm/rev). Figure 13: Ball-burnished surface (R = 5 mm, F = 2.5 kN, \(f_{\text{burn}}\) = 0.5 mm/rev)—the three-dimensional image of the burnishing zone. (direction of the main movement of the tool) and axial (in the feed direction) directions. A helical groove is created around the machined surface, with a helical pitch corresponding to the feed value (Figures 13 and 14). In the area of the deformation zone, a displaced \"fault\" is observed--a wave of the material formed in front of the tool. Shape deviations of the pressed material are the result of processes occurring within the displaced deformation zone. The geometry of the created deformation (width and depth of the groove, pitch of the formed helix, geometry of the formed material wave) results from the material parameters (mechanical properties, shape of the primary surface, initial roughness) and the adopted technological parameters of the process (selected tool). Figures 13 and 14 show images of the deformation zone for typical cases of burnishing (ball or disc with different radii).