Despite turning could be replaced by grinding as a finishing machining process, it is considered not satisfactory for elongating the fatigue life of the component because of the produced tensile residual stresses and irregularities formed at the surface. Therefore, a complimentary operation should be applied after hard turning. Slide diamond burnishing process is a mechanical finishing operation used after hard turning to further decrease the surface roughness, introducing compressive residual stresses, increasing the microhardness, and refining the microstructure of the surface and subsurface layer of the workpiece. The main result is increasing the fatigue life of the rotating components subjected to cyclic loading. In this work, the simultaneous effect of changing the burnishing speed, feed, and force of slide diamond burnishing on surface roughness, residual stresses, and microhardness of 42CrMo4 hard-turned steel was studied. It was found that the effect of one parameter was highly affected by the others. As a result, the optimal burnishing parameters were specified, with which better surface quality was obtained than after grinding.

Additive manufacturing (AM)’s ability to produce customized products with reduced material wastage and other advantages helped the technology to gain popularity in many industries. However, its poor surface integrity is its weak side, and to overcome this, additional post-processes are essential. Slide diamond burnishing, known for its enhancement of surface roughness, residual stress, microhardness, and other properties, was combined with grinding in this research after 3D printing of MetcoAdd 17-4PH-A to mitigate the mentioned shortcomings. This study aimed to analyze the effects of each process on surface roughness, residual stress (both on the surface and in-depth), and microhardness. Workpieces were ground with the same parameters and burnished with four levels of force, feed, and number of passes. The L16 Taguchi experimental design was used to optimize the process parameters and to study their effects. For surface roughness, the optimum parameters were found to be 60 N force, 0.02 m/min feed rate, and three passes. The longitudinal surface residual stress has optimal values at 80 N force, 0.02 m/min feed rate, and four passes. In the case of transverse surface residual stress, the optimal values were 60 N force, 0.17 m/min feed rate, and three passes. Microhardness was maximized with 60 N force, 0.02 m/min feed rate, and one pass. Additionally, the in-depth residual stress for selected surfaces was investigated, and 100 N force showed a deep burnishing effect. Further multi-objective optimization using desirability function analysis found that the optimal parameters for all responses were achieved at the fourth burnishing force level (100 N), the first tool feed level (0.02 m/min), and the fourth number of passes level (four passes). Ultimately, both grinding and burnishing processes exhibited significant enhancements in the measured parameters.

Surface roughness characterization plays an important role in the qualification of machined surfaces. As a result of the development of high resolution 3D scanning techniques, researchers and technologists have more possibilities to analyze surface topography in a more detailed way. The purpose of this study is determining the minimal measurement area size of surfaces hard machined by single-point and abrasive tools. Some important height parameters were analyzed: Sa, Sq, Sp, Sv, Ssk and Sku. It was found that the minimum area sizes vary for the different roughness parameters, however, in several cases minimization is possible, depending on the purpose of the surface analytics.