Search Results (18)

The paper presents the results of experimental research and surface characteristics after the process of roller burnishing of macro-asperities of the surface. As part of the work, the possibility of plastic shaping of the surface macrostructure with indentations (plateau structure), which will show anti-wear properties through appropriate surface shaping and the compressive stress state in the product’s top layer, was investigated. The essence of the paper is to present the analysis of the surface roughness parameters and carry out analysis of SEM, AFM and metallographic results for the burnished surface. The main objective of the work is to develop an adequate outline of the surface to receive the required parameters and characteristics of the surface after burnishing. The results of dependencies of roughness parameter after turning and after burnishing from the vertical angle of asperities are presented, as well as SEM, AFM and metallographic analysis for the surface with a vertical angle of 60 ÷ 150 degrees. Full article

This paper presents the effect of burnishing on the surface hardness, selected surface roughness parameters and material ratio of tubes made of an EN AW-6060 aluminum alloy after welding. The prepared specimens were subjected to a 141-TIG welding process, after which the surfaces to be burnished were given a finishing turning treatment with DURACARB’s CCGT09T302-DL cutting insert to remove the weld face. After the turning process, the surface finish treatment was carried out by rolling burnishing, for which Yamato’s SRMD burnishing tool was used. The surface hardness, selected surface roughness parameters and material ratio were then measured. An analysis of the results showed an increase in hardness in the surface layer, as well as an improvement in the analyzed surface roughness parameters and the material ratio of the native material and the weld. Full article

The generation of rough surfaces is an inherent drawback of selective laser melted (SLM) material that makes post-treatment operation a mandatory process to enhance its surface condition and service performance. However, planning an appropriate and optimized chain to attain the best surface finish needs an integrated simulation framework that includes physics of both additive manufacturing and post-processing. In the present work, an attempt is made to model the alternation of surface roughness which is produced by SLM and post-processed by milling and sequential surface burnishing. The framework includes a series of closed-form analytical solutions of all three processes embedded in a sequence where the output of the preceding operation is input of the sequential one. The results indicated that there is close agreement between the measured and predicted values of arithmetic surface roughness for both SLM material and the post-processed ones. It was also found that a nanoscale surface finish is obtained by finishing milling and single pass rolling at a static force of 1500 N. In addition, the results of the simulation showed that elimination of the milling process in the chain resulted in a six-times-longer production time that requires three times bigger rolling force compared to a chain with an included milling operation. Full article

The present work focusses on the research of the plastic deformation accumulated effect obtained after two different plastic deformation treatments, over the fatigue life of AISI 304 austenitic stainless steel. The research is focused on ball burnishing as a finishing process to form specific, so-called “regular micro-reliefs” (RMRs) on a pre-rolled stainless-steel sheet. RMRs are formed using a CNC (Computerized Numerically Controlled) milling machine and toolpaths with the shortest unfolded length, generated by an improved algorithm, based on the Euclidean Distance calculation. The effect of the predominant tool trajectory direction during the ball burnishing process (which can be coinciding or transverse with the rolling direction), the magnitude of applied deforming force, and feed-rate is subjected to evaluation using Bayesian rule analyses of experimentally obtained results for the fatigue life of AISI 304 steel. The obtained results give us reason to conclude that the fatigue life of researched steel is increased when directions of pre-rolled plastic deformation and the tool movement during ball burnishing are coincident. It also been found that the magnitude of deforming force has a stronger impact over the fatigue life, than the feed-rate of the ball tool. Full article

The surface cold working (SCW) of austenitic stainless steel (SS) causes martensitic transformation in the surface layers, and the percentage fraction of the strain-induced martensite depends on the degree of SCW. Higher content of α′−martensite increases the surface micro-hardness and fatigue strength, but deterioration of the corrosion resistance is possible. Therefore, the desired operational behaviour of austenitic SS can be ensured by the corresponding degree of SCW and heat treatment. This article evaluates the effects of SCW performed by diamond burnishing (DB) and heat treatment on the surface integrity (SI), rotating fatigue strength, and corrosion resistance of AISI 304 austenitic SS for two initial states: as-received hot-rolled bar and initially heat-treated at 1100 °C for one hour followed by quenching in water. Then, DB was implemented as a smoothing and hardening process, both alone and in combination with heat treatment at 350 °C for three hours after DB. The electrochemical performance was examined by open circuit potential measurements, followed by potentiodynamic tests. For both initial states, smoothing DB provided the lowest roughness, whereas an improvement in the maximum surface micro-hardness was obtained after hardening DB and subsequent heat treatment. The maximum fatigue strength was obtained by hardening multi-pass DB without subsequent heat treatment for the as-received initial state. Smoothing DB and subsequent heat treatment maximised the surface corrosion resistance for the two initial states, whereas a minimum corrosion rate was obtained for the initially heat-treated state. For the as-received state, smoothing DB and subsequent heat treatment simultaneously lead to a high fatigue limit (equal to that obtained by hardening single-pass DB) and a low corrosion rate. Full article

Aluminium bronzes are widely used in various industries because of their unique properties, a combination of high strength, wear resistance, and corrosion resistance in aggressive environments, including seawater. In this study, the subject of comprehensive experimental research was Cu-10Al-5Fe iron-aluminium bronze (IAB) with β-transformation, received in the form of hot-rolled bars. The effects of different heat treatments (HT) and severe surface plastic deformation (SPD), conducted by diamond burnishing (DB) on the microstructure, surface integrity (SI), mechanical properties, low- and mega-cycle fatigue strength, and dry sliding wear resistance, were determined. Based on quantitative indicators, the applied heat treatments in combination with severe SPD were compared. Thus, the integral efficiency of the heat treatments was evaluated, and the heat treatments were correlated with the resulting properties and operational behaviour of Cu-10Al-5Fe IAB. For example, if the component is designed for rotational bending conditions, the combination of quenching at 920 °C in water, subsequent tempering at 300 °C for three hours, and DB provides maximum fatigue strength in both low-cycle and mega-cycle fatigue applications. Full article

Roller burnishing represents an economical alternative to conventional surface-finishing processes, such as fine turning or honing. In contrast to the well-known wear mechanisms of chip-forming processes, the wear behavior in roller-burnishing is strongly based on the experience of the machine operators. The nature of the finishing process makes roller-burnishing very sensitive to surface defects, as it is often not possible to rework the last step in a process chain. In the present work, a prototype for a smart roller-burnishing tool with 5G communication is presented, which serves as an inline-monitoring tool to detect tool wear. A suitable metric to monitor the tool wear of the manufacturing roll is suggested, and the potentials of 5G communication for the described use-case are evaluated. Based on the signal-to-noise ratio of the process-force, a metric is found that distinguishes new rolls from worn rolls with very small defects on the micrometer scale. Using the presented approach, it was possible to distinguish the signal-to-noise ratio of a roll with very small wear marks by 3.8% on average. In the case of stronger wear marks, on the order of 20 µm, the difference increased to up to 15.6%. Full article

The study was carried out on a KRUMAN-CLS1016-NC shearing machine at a shear temperature of 20 °C to 250 °C and a shear edge clearance of 8% to 10% for a rolled AZ31B magnesium alloy plate with a thickness of 8.35 mm. The height and area share of the bright zone in the shear section were analyzed by macroscopic measurements and super depth-of-field experiments, and combined with DEFORM-3D finite element simulations, the optimal shear program was determined using the orthogonal experimental method. It was found that, with the increase of shear temperature and shear edge clearance, the height and area of the burnish band first increased and then decreased. In addition, from the simulated orthogonal test, it can be obtained that the effect of shear temperature on the height of the burnish band is superior to that of the shear edge gap, so the selection of shear temperature is preferred. In this paper, the shear temperature of 150 °C and the shear edge clearance of 12% were finally determined as the best shear process parameters for the rolled AZ31B magnesium alloy sheet. Full article

Surface roughness is an important indicator of the quality of the machined surface. One of the methods that can be applied to improve surface roughness is ball burnishing. Ball burnishing is a finishing process in which a ball is rolled over the workpiece surface. Defining adequate input variables of the ball burnishing process to ensure obtaining the required surface roughness is a typical problem in scientific research. This paper presents the results of experiments to investigate ball burnishing of AISI 4130 alloy steel with a high-stiffness tool and a ceramic ball. The experiments were conducted following a randomized full factorial design for different levels of input variables. The input variables included the initial arithmetic mean roughness (the initial surface roughness), the depth of ball penetration, the burnishing feed, and the burnishing ball diameter, while the output variable was the arithmetic mean roughness after ball burnishing (the final surface roughness). The surface roughness modeling was performed based on the experimental results, using regression analysis (RA), artificial neural network (ANN), and support vector regression (SVR). The regression model displayed large prediction errors at low surface roughness values (below 1 μm), but it proved to be reliable for higher roughness values. The ANN and SVR models have excellently predicted roughness across a range of input variables. Mean percentage error (MPE) during the experimental training research was 29.727%, 0.995%, and 1.592%, and MPE in the confirmation experiments was 34.534%, 1.559%, and 2.164%, for RA, ANN, and SVR, respectively. Based on the obtained MPEs, it can be concluded that the application of ANN and SVR was adequate for modeling the ball burnishing process and prediction of the roughness of the treated surface in terms of the possibility of practical application in real industrial conditions. Full article

The article presents the results of investigations into the depth of the plastically deformed surface layer in the roller burnishing process. The investigation was carried out in order to obtain information on the dependence relationship between the depth of plastic deformation, the pressure on the roller and the braking torque. The research was carried out according to the original method developed by the authors, in which the depth of plastic deformation is increased by applying a braking torque to the burnishing roller. In this method, it is possible to significantly increase (up to 20%) the depth of plastic deformation of the surface layer. The tests were carried out on a specially designed device on which the braking torque can be set and the force of the rolling resistance of the roller during burnishing can be measured. The tests were carried out on specimens made of C45 heat-treatable carbon steel. The dependence of the depth of the plastically deformed surface layer was determined for a given pressure force and variable braking moments. The depth of the plastically deformed layer was measured on the deformed end face of the ring-shaped samples. The microhardness in the sample cross-section and the evolution of the microstructure were both analysed. Full article

Several manufacturing processes are used to beneficially influence the surface and subsurface properties of manufactured parts. Different aspects such as the surface topography or resulting residual stresses are addressed using different manufacturing processes. This paper presents the first approach for pulsed mechanical surface treatment (PMST), a new manufacturing process aiming to combine the mechanics used in deep rolling and shot or hammer peening. The process can generate a defined surface topography while constantly impinging a mechanical impact on the workpiece. Two different tools (type 1 and type 2) have been designed to approach this new concept. Hardened carbide pins are used for type 1 to prove the concept using a simpler kinematic and resulting in a burnishing-like process. For type 2, hardened roller is used and results in an actual rolling process. Specimens made of S235 are processed in experiments with tool type 1 with varying pulse frequency and feeds. The resulting surface topography is described using optical measurement systems while micro-hardness measurements are used to describe the subsurface properties. The results in general show an increase of hardness in the surface and subsurface layer while the resulting surface topography can be directly controlled by the process parameters and therefore be designed for specific functional properties. Full article

The present study examines the fatigue of friction stir welded (FSW) aluminum 6061, 7075, 1060 joints followed by (i) in situ and sequential rolling (SR) processes, (ii) plastic burnishing (iii) solution-treatment artificial aging (STA), (iv) local alloying through depositing thin copper foils, and (v) inserting alumina powder in the weld nugget zone (NZ). The microstructural features and fatigue life of post-processed joints were compared with those of as-welded joints. The in situ rolling technique offered simultaneous rolling and welding operations of aluminum joints, while through the sequential rolling process, the top surface of FSW joints was rolled after the welding process. The fatigue life of in situ rolled samples was increased as the ball diameter of welding tool increased. The fatigue life of friction stir welded joints after a low-plasticity burnishing process was noticeably promoted. The addition of 1 wt.% alumina in the NZ of joints resulted in a significant elevation on fatigue life of friction stir spot welded joints, while an increase in alumina powder to 2.5 wt.% adversely affected fatigue strength. Weld NZ was alloyed through the insertion of copper foils between the faying surfaces of joints. This localized alloy slightly improved the fatigue life of joints; however, its effects on fatigue life were not as influential as STA heat-treated or in situ rolled joints. The microstructure of weld joints was highly affected through post-processing and treatments, resulting in a substantial influence on the fatigue response of FSW aluminum joints. Full article

Vibration-Assisted Ball Burnishing is a finishing processed based on plastic deformation by means of a preloaded ball on a certain surface that rolls over it following a certain trajectory previously programmed while vibrating vertically. The dynamics of the process are based on the activation of the acoustoplastic effect on the material by means of the vibratory signal transmitted through the material lattice as a consequence of the mentioned oscillation of the ball. Materials processed by VABB show a modified surface in terms of topology distribution and scale, superior if compared to the results of the non-assisted process. Subgrain formation one of the main drivers that explain the change in hardness and residual stress resulting from the process. Full article

Causes of the in-service damage to hydrocylinder liners were investigated, and the requirements to their working surfaces were systematized. Roughness parameter Ra was found not to provide a precise estimate of the surface quality because its reduction did not affect surface microgeometry. Additionally, the surface quality was assessed by the Abbott-Firestone curve during the finishing operation. The optimized manufacturing technology for obtaining hydrocylinder liners was offered based on having the required microgeometry and surface quality provided by cutting operations. The quality and service characteristics of internal surfaces of hydrocylinder liners were improved by changing technological operations. In particular, the semi-finish turning was chosen to provide for the surface roughness parameter Ra within 6.3–8.0 μm and the roughness pitch parameter S within 0.4–0.6 mm and homogeneous surface structure. The finishing rolling was replaced by burnishing to form a regular microrelief. Full article

During the low plasticity burnishing process of soft materials such as carbon steel with a hardness of up to 40 HRC (Rockwell grade) a raised structure of the material known as the Jumping Wave forms in front of the tool roll. This phenomenon significantly disturbs the burnishing process, but is very poorly described in the literature. This article presents studies of this phenomenon on the example of burnished 1.0562 steel. The research concerns the changes in the surface structure of the processed material as well as changes in the structure of the material during this process. The research shows changes in the geometric structure of the surface made in the 3D system and their parametric description. Moreover, the work presents an analysis of the metallographic structure in the tool zone. The research showed occurrence of material slippages in the wave in front of the tool, which creates an additional structure on the surface. These tests make it possible to better understand the process of changes that take place in the surface layer of the processed element in the low plasticity burnishing process. Full article