Chromium–nickel austenitic stainless steels are widely used in various industries after their initial hardness and strength are increased. Apart from low-temperature thermal–chemical diffusion, the mechanical properties can be improved by surface cold working (SCW). A cheap and reliable form of static SCW is diamond burnishing (DB), which drastically improves the surface integrity (SI) and hence the operational behavior of the processed component. To be maximally effective, the DB parameters must be optimized according to a relevant criterion, depending on the desired effect. For high fatigue strength and/or high wear resistance, complex experimental tests are necessary, which require significant time and financial resources. This study presents a cost-effective optimization approach based on the DB process–SI–operating behavior correlations. Using these correlations, in addition to the correlations between appropriately selected SI characteristics, the proposed approach relies on the control of only three easy-to-measure roughness parameters, namely the arithmetic average roughness, skewness, and kurtosis, which, in turn, depend on the governing factors of the DB process.

The main goal of this study is to develop an optimized sustainable combined process, including sequential dry hard turning and dry smoothing diamond burnishing (DB), to improve the surface integrity (SI) and fatigue limit of heat-treated 42CrMo4 steel shafts and axles. A holistic approach was used based on a two-stage study: (1) optimization of dry hard turning under an average roughness Ra criterion and (2) selection of a suitable dry DB from three alternative DB processes, implemented with burnishing forces of 50, 100, and 150 N. With increasing burnishing force, the average roughness of Ra decreases, the microhardness increases, and the surface axial residual stresses increase in absolute value. However, the fatigue limit decreases, and at burnishing forces of 100 and 150 N, the fatigue limit is smaller than that obtained via the previous turning. The sustainable combined process achieves greater SI than consecutively applied conventional turning and DB under flood lubrication conditions. Dry DB at a force of 50 N increases the rotating bending fatigue limit by 20 MPa and the fatigue life by a factor of more than 70 compared to the previous dry turning.

There is a lack of information in the literature on the influence of technological heredity on surface integrity characteristics after diamond burnishing (DB). The present study fills this gap. Here, we present the effects of DB on the roughness parameters and surface microhardness of heat-treated C45 steel under conditions of changing initial roughness (Ra^init) due to wear on the cutting insert in the previous turning. The aim was to quantitatively assess the ability of DB to maintain sustainable surface integrity characteristics. We found that the service life of the cutting insert up to complete wear or fracture when operating at an optimal feed rate and cutting velocity was 163 min, at which point the roughness changed unevenly from an average roughness (Ra) value of 0.38 to 1.31 μm and an average height of the profile microroughness (Rz) value of 2.21 to 6.13 μm. Under conditions of an artificially created Ra^init (through different combinations of feed rate and cutting velocity) of 0.308 to 10.688 μm, DB provided Ra values in the range of 0.042 to 0.316 μm, with the surface microhardness varying from 461 to 568 HV. Stable Ra values were maintained from 0.042 μm to 0.089 μm, after which the Ra^init increased to 3.379 μm. Under production conditions, where the previous turning was performed at an optimal feed rate of 0.05 mm/rev and a cutting velocity of 180 m/min, DB provided a stable Ra of ≤0.059 μm of a resulting mirror-like surface during the first 90 min of operation of a new (unused) cutting insert, after which the Ra values increased linearly from 0.059 to 0.133 μm in the 150th minute. After 30 min of operation, until the cutting insert was completely worn, the microhardness after DB varied from 676 to 795 HV, the high surface microhardness resulting from a complex process of surface thermo-mechanical strengthening (including strain and transformation hardening) in the previous turning due to wear on the cutting insert.

To disclose the capabilities of slide burnishing (SB) conducted using a cylindrical-ended, non-diamond-based deforming element to improve the roughness of CuZn39Pb3 alloy components.A full factorial experiment, analysis of variance, regression analysis, and an optimisation procedure based on the NSGA II algorithm were employed.The Ferro-Tic Grade C hard alloy can be successfully used to produce deforming elements in burnishing processes, when the processed material is a copper-based alloy. Under conditions of tangential sliding friction contact between the deforming element and the processed surface, no negative effects due to adhesion were observed.The research answered some questions about improving the roughness of CuZn39Pb3 alloy components, but also revealed the need for future research on the SB of this alloy using Ferro-Tic Grade C hard-alloy deforming elements.The optimal values of the governing factors (radius of 5 mm, burnishing force of 207 N, feed rate of 0.089 mm/rev, and burnishing velocity of 70 m/min) yielded a minimum value of the Ra roughness parameter of 0.139 μm. Understanding the correlation between roughness and operating behaviour can significantly improve the fatigue, tribological, and corrosion behaviour of such a component.The literature lacks information on the effects of surface plastic deformation on the surface integrity (SI) of the alloy. There is also a lack of information on the technological capabilities of the hard alloy Ferro-Tic Grade C used as a deforming element in the burnishing process. The study partially fills this gap by shedding light on the effect of SB on the roughness.

In this study, a sustainable advanced manufacturing technology was developed using a holistic approach for finishing heat-treated 42CrMo4 steel cylindrical parts. The proposed technology is based on a hybrid combined process (HCP) involving cool-assisted dry hard turning and subsequent cool-assisted dry diamond burnishing (DB). A cold-air cooling (without lubrication) condition was achieved using a special device with a cold-air nozzle based on the principle of vortex tubes. The study was conducted in two stages. In the first stage, only the hard turning process was investigated using variance analysis to determine the significant governing factors (feed rate and cutting insert radius). The second stage involved studying and optimising the HCP. This approach incorporated the two significant turning process factors, along with three additional DB process factors: the radius of the diamond insert, burnishing force and feed rate. The selected objective functions were the average roughness, skewness, kurtosis, surface microhardness, residual surface axial stress and fatigue limit. The fatigue limit was determined using the accelerated Locati method. Mathematical models of the objective functions were obtained using experiments and regression analyses. Using multi-objective optimisation, the HCP was optimised based on two criteria: (1) maximum wear resistance under boundary lubrication conditions and (2) maximum fatigue limit. The optimisation tasks were solved by searching for the Pareto optimal solution approach using QStatLab and the NSGA II algorithm. The compromise optimal values of the governing factors, maximising the fatigue limit (690 MPa), are as follows: feed rate in turning and DB of 0.05 mm/rev, radius of the cutting insert of 0.8 mm, diamond insert radius of 2 mm, and burnishing force of 50 N. Experimental verification showed a good agreement with the optimised solutions for surface integrity and fatigue limit characteristics.

CuZn39Pb3 leaded brass is one of the most widely used alloys in machining, with a 100% machinability index. However, there has been a lack of research on the effects of coldworking on surface integrity (SI) and operating behaviour of CuZn39Pb3 components. This study addresses this knowledge gap by examining the effects of three optimised combined processes on surface roughness, a key SI characteristic. Specifically, samples were subjected to a turning process followed by diamond burnishing (DB); this combined process was performed under three conditions: conventional flood lubrication (F), dry (D), and dry and cool-assisted (D+C) conditions. Cool-assisted conditions were achieved using a special device with a cold air nozzle operating on the vortex tube principle. The D and D+C conditions represent environmentally sustainable alternatives because they eliminate the use of cutting fluids, thereby reducing their adverse effects on both the environment and human health. The resulting surfaces obtained after each of the three optimised combined processes (F, D, and D+C) exhibited mirror-like finishes with minimum average roughness Ra values of 0.054, 0.079, and 0.082 μm, respectively. In addition, the F- and D+C-processes resulted in surface profiles with negative skewness and kurtosis values greater than three. Since roughness shape parameters are known to influence the operating behaviour of machined components, these processes are suitable for improving wear resistance in boundary lubrication regimes.