# Determining Optimal Parameters of Regular Microrelief Formed on the End Surfaces of Rotary Bodies
## 1 Introduction  
End surfaces of rotary bodies are widely used as working surfaces of actuators in modern automotive and mechanical engineering. These include conical disks of continuously variable transmission of automatic transmissions of cars, parts of end bearings (both tapered and axial) [1, 2, 3, 4], valves of gas-distributing mechanisms of internal combustion engines, and so on. These surfaces are usually exposed to high operating temperatures and specific pressures [5, 6]. Using plastic deformation of the surface to form a regular microrelief on the conjugated working surfaces of heavily loaded friction pairs allows enhancing their durability [7, 8, 9, 10]. Fundamental in terms of findings obtained in the study of the influence of rolling modes on the surface layer structure of the treated surface is work [11]. The authors established the influence of burnishing force and rolling feed on the roughness parameters of the rolled surface. In addition, the authors investigated residual stresses in-depth (in the axial direction) at different feed rates of rolled materials (prediction of residual stresses (in the axial direction) for different burnishing feed rates, along with depth). The result of comparing the structure of the material obtained by ball burnishing and shifted in the axial direction of the roller allowed us to systematize the influence of technological parameters and structural components of the material. Specific parameters of the relative area of burnishing are challenging to provide when grooves of partially regular microrelief (PRMR) of the 3 rd type are formed, which are characterized by an overlap of the groove. Therefore, the formation of PRMR of the 3 rd type with a given relative area of burnishing on the rotary body end surfaces (RBES) is a rather complex technological task. The formation of a regular microrelief on the conjugated working surfaces of heavily loaded friction pairs significantly enhances their functional properties and, accordingly, theservice life of the unit itself [12; 13; 14]. The regular microrelief's positive effect on the surface roughness parameters is also described in [15]. A regular microrelief was formed on the outer cylindrical surfaces of specimens from medium-carbon steel 1C45 and low-carbon alloy steel 18 CrMn4-4, which were used to determine the effect of processing conditions on the surface roughness and hardness. One of the leading research findings was that a significant influence of the vibration amplitude was found to be the most determining factor for the surface roughness parameter \(R_{a}\). In [16], the effect of changes in the deformation force and feed rate on the surface roughness parameters during burnishing and the mechanical properties of the surface layer was investigated. In addition, surface parameters obtained by ball burnishing and milling were compared. The range of optimal pressure values at the processing of specimens by ball burnishing (ball burnishing treatment), at which values of roughness parameters will be minimal, was established. In [17], the relative area of the regular microrelief (RMR) \(F_{n}\) was presented as the ratio of the area occupied by regular roughness \(F_{gr}\) to the surface area of the part to be processed \(F_{w}\). According to [1], the relative surface area \(F_{n}\) was a partially regular microrelief parameter, which most fully characterizes almost all the surface's functional properties and, primarily, the actual contact area of one surface. Therefore, the regular microrelief Fn's relative surface area was one of its most important indicators, which characterizes the working properties of the surface on which it is formed. Its optimal value varies between 30-45% depending on the conjugated surfaces' operating conditions [18]. The optimal relative areas of burnishing of the regular microrelief depending on the operating conditions of the machine parts' cylindrical surfaces were studied in detail in [19; 20; 21].