Roller Burnishing Research Articles

Effects of microstructure and inherent stress on residual stress induced during powder bed fusion with roller burnishing

A hybrid metal-additive manufacturing (AM) process that combines laser-based powder bed fusion (PBF-LB) with interlayer burnishing is investigated using a comprehensive modeling framework to provide new insights into how the inhomogeneous microstructure and residual stress from the laser powder bed fusion process affect the induced residual stress field that evolves during interlayer burnishing. Researchers have recently studied changes in microstructure resulting from similar hybrid metal-additive processes, however, it was only hypothesized that the resulting microstructure has some influence on the induced residual stress. In addition, researchers have numerically investigated the influence of burnishing/rolling process parameters on induced stress but neglected the effects of microstructure, thereby making homogeneous, isotropic assumptions. Such practice inhibits the prediction of microstructure-driven anisotropy that can exist in the inhomogeneous fused layer. This paper parametrically examines the influence of microstructure modeling, inherent residual stress mapping, and environment temperature on the induced residual stress during the hybrid metal-additive process. The demonstrated modeling framework incorporates inherent residual stresses that emerge from the laser powder bed fusion process, as well as the predicted microstructure, in a subsequent burnishing simulation to elucidate their individual and combined influences on the burnishing-induced residual stress. Findings reveal that modeling an inhomogeneous PBF-LB microstructure introduces an anisotropic distribution of plastic strain and residual stress along the burnished surface; a periodicity in planar stress components along the treated surface coincides with the PBF-LB scan lines. Effects of inherent residual stress on the burnishing-induced residual stress is less significant, but nonetheless observable. Elevated temperatures not only reduce the magnitude of compressive residual stress induced but also result in less variation of residual stress component magnitudes predicted along scan lines and hatch spaces. The presented framework offers new insights into the decoupled influences of microstructure and PBF-LB residual stress on burnishing-induced stresses that are not distinguishable via experimental techniques. However, trends in averaged residual stress through the depth of the specimen, as well as surface hardness magnitudes after burnishing show good agreements, respectively, with X-ray diffraction and microindentation measurements documented in the literature.

Analysis of the Inconel 718 properties after roller burnishing

Experimental studies were performed to investigate the influence of roller burnishing (RB) parameters, as the temperature and the number of RB operations, on the subsurface microstructures and microhardness, surface roughness and roundness deviation of the Inconel 718 alloy. The experimental results indicate that the RB enhance the surface quality, reduces the surface roughness by 76.7% and increase the microhardness by 20.9% compared to the turned part. RB affects the microstructural morphology of the subsurface grains and improves roundness deviation of Inconel 718 parts. The presence of precipitates in the plastic deformation zone contributes to increase the mechanical strength of the subsurface. The RB operation, both at room temperature and at 310°C, proved to be very efficient in reducing the surface roughness of the Inconel 718. About roundness deviation, the increase of the RB temperature induces a greater specimen roundness deviation, and the hot RB operation is not favourable to improve the circularity of the specimen.

Analysis of the Inconel 718 properties after roller burnishing.

Analysis of the Inconel 718 properties after roller burnishing.

Enhancing Surface Integrity of Additively Manufactured Inconel 718 by Roller Burnishing Process

This work presents the effect of burnishing process including burnishing force, burnishing speed and burnishing conditions on surface properties of Inconel 718 alloy fabricated by laser powder based fusion additive manufacturing. As-built, sand blasted and heat-treated specimens are burnished and final surface properties such as surface roughness, surface topography, and microhardness are presented. The performance of the burnished surface is tested through wear test. This study reveals that burnishing process makes substantial contribution to reduce surface roughness of additively manufactured Inconel 718 alloy. Moreover, surface hardness is notably increased resulting from burnishing process and hence wear resistance of this alloy improved. Wear resistance of as-built specimens was increased by 38% through implementing roller burnishing. Wear resistance of heat-treated specimens is increased by 55% through implementing roller burnishing process.

Hybrid additive manufacturing of metal laminated forming tools

Deep drawing dies are manufactured using metal sheets. Laser metal deposition is used for bonding the sheets and smoothening the edges. The strength and surface finish of the dies are the key challenges. Milling, roller burnishing, and laser treatment are applied as post-processing for improving the surface finish. A semi-analytical model is developed for selecting the sheet combination for sufficient strength. The new rapid prototyping process offers high flexibility for complex die geometries. The evaluation by deep drawing experiments using DC06 and high-strength HC380LA blanks revealed the feasibility of the new manufacturing routes regarding deep drawability and surface finish.

Effect of Roller Burnishing on the Plasma Nitriding of Tool Steel SKD61

Effect of Roller Burnishing on the Plasma Nitriding of Tool Steel SKD61

Parameter optimization during single roller burnishing of AA6061-T6 alloy by design of experiments

Roller burnishing is a surface finishing process that involves plastic deformation of the surface without any removal of the material. The level of surface finish that can be attained in roller burnishing operation depends on several process parameters. Processing at the optimum combination of process parameters is critical for achieving a higher yield during manufacturing. Hence, the present study is carried out to obtain the optimized process parameters during roller burnishing of aluminium alloy AA6061-T6, with an objective to produce a high level of surface finish. The Taguchi method has been used to assess the role of burnishing speed, feed rate, and load on the surface finishing of the alloy. Analysis of variance (ANOVA) and signal-to-noise ratio (S/N) have been employed to analyze, obtain significant parameters, and find out optimum combination levels of the process parameters. The results show that the surface quality of the specimens is significantly improved with burnishing parameters. The analysis of the results shows that the burnishing feed rate has the highest impact on the surface roughness with a contribution of 54.51%, followed by load and burnishing speed.

Experimental and Numerical Analysis of the Depth of the Strengthened Layer on Shafts Resulting from Roller Burnishing with Roller Braking Moment.

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.

Characterization of microstructure and mechanical properties for Ti-6Al-4 V processed by rotary ultrasonic roller burnishing

Ultrasonic assisted surface plastic deformation can significantly improve the mechanical properties of metal material by grain refinement and crystallographic texture. This paper investigated the effect of microstructure evolution on the microhardness and residual stress for Ti-6Al-4 V treated by rotary ultrasonic roller burnishing. The microstructure evolution of α and β phases was explained from grain size, crystallographic texture, misorientation, grain boundary and recrystallization. Crystallite rotation caused by ultrasonic vibration introduced strong crystallographic textures on the cross-sections of Ti-6Al-4 V samples. When ultrasonic amplitude was 7 μm, a strong {0001} <112¯0> texture appeared on the cross-section. The strength of α grain with {0001} texture orientation was larger than that of α grains with other texture orientations. The mean grain size of Ti-6Al-4 V cross-sectional sample was 7.39 μm at an ultrasonic amplitude of 7 μm. The corresponding maximum microhardness value 392.4 HV was larger than that measured at other ultrasonic amplitudes. However, the maximum compressive residual stress affected depth was obtained at an ultrasonic amplitude of 10 μm. The high microhardness of Ti-6Al-4 V was attributed to the grain refinement and crystallographic texture distribution of α and β phases in RURB. The high compressive residual stress affected depth was related to the fraction of deformed grain for α and β phases in RURB.

Optimization of external roller burnishing process on magnesium silicon carbide metal matrix composite using response surface methodology

Optimization of external roller burnishing process on magnesium silicon carbide metal matrix composite using response surface methodology

Effect of burnishing on Inconel 718 workpiece surface heated by infrared radiation

ABSTRACT Roller burnishing process is a post-machining surface finishing technique that has an advantage over other finishing processes, such as shot blasting or abrasive-tooling processes, because of its simplicity and excellent results (both improved surface finish and improving the mechanical properties of the material). Roller burnishing allows you to eliminate the part grinding step. Nickel super alloys, in turn, including the Inconel 718 have wide application in the aerospace industry due to their high fatigue strength and their ability to work at elevated temperatures. The Inconel 718 shows a predominantly austenitic matrix (γ phase), which under the burnishing process trends to produce an increase in hardness and residual stress. This paper is the result of research on the influence of the conventional roller rolling process at room temperature and at 310°C on a turned part of Inconel 718. Results of surface roughness, roundness deviation, microhardness, residual stress, and deformation of the material under a load of 850 N were analyzed. The obtained results prove the improvement of the material properties after the roller burnishing process: lower values of surface roughness, higher roundness deviation in conventional burnishing, higher surface hardness and higher compressive residual stress in hot burnished specimen.

Optimization of the Internal Roller Burnishing Process for Energy Reduction and Surface Properties

Improving the surface quality after burnishing operation has been the subject of various published investigations. Unfortunately, the trade-off analysis between the energy consumption and surface characteristics of the internal burnishing has been not addressed due to the expensive cost and huge efforts required. The objective of the present work is to optimize burnishing factors, including the spindle speed, burnishing feed, depth of penetration, and the number of rollers for minimizing the energy consumed in the burnishing time, as well as surface roughness and maximizing Rockwell hardness. An adaptive neuro-based-fuzzy inference system (ANFIS) was used to develop burnishing objectives in terms of machining parameters. The optimization outcomes were selected using an evolution algorithm, specifically the non-dominated sorting particle swarm optimization (NSPSO). The results of the proposed ANFIS models are significant and can be employed to predict response values in industrial applications. The optimization technique comprising the ANFIS and NOPSO is a powerful approach to model burnishing performances and select optimal parameters as compared to the trial and error method as well as operator experience. Finally, the optimal solution can help to achieve the improvements in the energy consumed by 16.3 %, surface roughness by 24.3 %, and Rockwell hardness by 4.0 %, as compared to the common values.

Effect of Number of Passes on Surface Properties of Burnished Aluminium Alloy

Basically, roller burnishing process is one of the surface finishing processes. In this process, a hard and highly polished roller will be pressed against a rotating specimen, this causes plastic flow on specimen surface from the peaks of surface irregularities into the valleys, which results in a reduction in the surface roughness considerably. This is a type of cold working whichalso results in improvementof micro-hardness, refinement of microstructure on the surface of the specimen under consideration. This work aims to understand the versatility of roller burnishing processand to understand the effect of the number of burnishing passes to enhance surface properties. Surfaceroughness, electrical conductivityand microhardness were studied in the present work. Experimental work was done on aluminium AA7075-T6 alloy. The parameters under which the burnishing was done were burnishing force, spindle feed and speed and are kept constant in the present work.

On the Effects of Burnishing Process on Tribological Surface Resistance of Additively Manufactured Steel

Burnishing is a Severe Plastic Deformation process having the potential to replace expensive finishing post processes. It is considered a super finishing process due to its results in terms of drastic roughness reduction. Also, additional advantages include the surface integrity improvement functionalized to the specific application. Even though burnishing is widely applied for surface improvement of conventional materials, knowledge about its effect on additively manufactured metals is still limited. This paper aims to fill this gap presenting experiments on roller burnishing on additively manufactured stainless steel in order to improve its tribological performance. The experimental campaign was carried out to find suitable process parameters able to drastically improve the tribological behavior of the final product. In particular, the influence of the burnishing forces on the whole surface quality has been addressed. The overall results demonstrate that the selected burnishing configuration is able to successfully modify the surface characteristics of the steel, making it appropriate for critical applications. Furthermore, the experimental findings allow to conclude that burnishing process can replace a series of post processes needed after additive manufacturing, drastically reducing the time and costs associated to the manufacturing process and meeting Industry 4.0 requirements.

Improvement in Fatigue Performance of 2024-T3 Al Alloy Via Single Toroidal Roller Burnishing

Mechanical surface treatment, based on static severe plastic deformation of the surface layer, is a cost-effective approach to improving surface integrity and thus the operating properties of metal components. The present work examines the possibility of using single toroidal roller burnishing (STRB) to implement the deep rolling concept. The effect of the STRB process parameters on the fatigue behavior of 2024-T3 Al alloy specimens is investigated. The specimens were manufactured using a newly developed STRB device. The conventional fatigue limit of 2024-T3 Al alloy is established using the S–N curve approach and tangent method. The STRB implementation as the deep rolling process for 2024-T3 Al alloy specimens provides a maximum conventional fatigue limit of 256 MPa. Compared to the reference condition, the fatigue limit has increased by 38.4%. Calculated at the number of cycles corresponding to the conventional fatigue limit, the fatigue life is enhanced more than 2000 times over. The increase in the number of passes enhances the fatigue strength: as a result the conventional fatigue limit of the treated 2024-T3 Al alloy increased. Increasing the number of passes has practical meaning for up to six passes, after which the effect is negligible.

Enhanced Surface Quality of Internal Machined Contours

Based on integrated concepts in the aspects of product design, choice of materials and manufacturing technologies, companies in the mechanical engineering as well as oil and gas industries are striving to increase energy efficiency through weight-optimized components and manufacturing processes. With regard to the design of e.g. functional components for hydraulic systems or aircraft structures, customized manufacturing concepts are crucial in order to combine the highest product quality with the economical use of energy and resources. The use of a flexible tooling system for combined internal contouring and mechanical post-processing of boreholes developed within the framework of a ZIM project, founded by the Federal Ministry for Economic Affairs and Energy and in collaboration with BGTB GmbH makes it possible to achieve highest surface qualities of high-performance components. In order to realize a further optimization of the machined surface, the influences of increased operating pressures during roller burnishing on surface smoothing are investigated in analogy tests. In this regard, different steel types are considered as typical application materials. Based on reference tests, the surface integrity as a result of increased working pressures was analyzed as well. Besides the variation of the mechanically applied force, the adjustment of the process strategy is a central issue of the experimental investigations. On the one hand, the influences of varying roll feeds are analyzed with reference to the surface finishing quality and the process efficiency. On the other hand, different strategies for surface improvements increase by varying holding pressures are assessed comparatively.

Hardness and wear resistance of roller burnished 316L stainless steel

This study investigates the effects of roller burnishing on the microstructure, surface microhardness, and wear resistance of 316L stainless steel. Experimental design based on the Taguchi orthogonal array was employed to determine the optimized parameter set for maximizing the burnished surface microhardness. Roller burnishing refined the microstructure beneath the surface and improved the microhardness by 45%. Subsequently, results of reciprocating tribological experiments revealed a significant increase in the wear resistance after the burnishing process.

Finite element and experimental study of the residual stresses in 2024-T3 Al alloy treated via single toroidal roller burnishing

This article presents the outcomes of finite element (FE) simulations and X-ray stress measurements of residual stresses in high-strength 2024-T3 Al alloy introduced via the single toroidal roller burnishing (STRB) process. In terms of the deforming toroidal roller geometry, STRB is particularly suitable for deep rolling. A 3D FE model was developed using the flow stress concept, and the actual STRB kinematics was simulated to evaluate both hoop and axial residual stresses. The FE model was validated through a comparison of FE and X-ray residual stress distributions. The effects of the burnishing force, feed rate, and number of passes on the residual hoop and axial stresses were studied. It was established that increasing the feed rate leads to a decrease in the residual hoop stresses and an increase in the residual axial stresses. The greater burnishing force increases the compressive zone depth and only slightly increases the surface residual stresses. The FE and X-ray stress analyses confirm the effectiveness of STRB of 2024-T3 Al alloy to introduce significant residual compressive axial and hoop stresses.

Researches and Simulation of Elastic Recovery Phenomena during Roller Burnishing Process of Macro-Asperities of Surface.

The paper presents preliminary studies of a new innovative surface treatment method—the process of roller burnishing of macro-irregularities 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 the analysis of one of the aspects of the application of this processing method, i.e., the influence of the elastic recovery of the product on its technological quality measured by dimensional deviation. The main objective of the work is to develop adequate methods and mathematical models to enable the design of the macro-asperities of the surface burnishing process to maintain the dimensional tolerance of the shaped parts. The results of dependencies of elastic recovery of the asperities and the deviation of height, Δht, for sample depths of burnishing were presented. The model tests of the elastic recovery of the model material using the visioplasticity method show that with the increase of the value of the vertical surface asperities, the value of the elastic recovery of the material decreases. The increase of the deviation of the asperities’ height causes a decrease in the value of elastic recovery. With the increase of the value of the vertical angle of the surface roughness, the value of the elastic recovery of the material is smaller.

Single toroidal roller burnishing of 2024-T3 Al alloy implemented as mixed burnishing process

Based on a comprehensive experimental study, single toroidal roller burnishing (STRB) of the 2024-T3 Al alloy can be successfully implemented as a mixed burnishing process. Optimum values of various governing factors provided minimum roughness and significant enhancement of the fatigue life of the treated specimens. With a planned experiment, regression analysis, and optimization procedure based on a genetic algorithm, the optimum factor values were established under a minimum roughness criterion. The derived model predicted a minimum roughness Ra = 0.074 μm. The experiment with optimal process parameters provided an average roughness (Ra) of 0.01 μm. STRB under these optimal conditions yields a relatively homogeneous surface in terms of microhardness with a surface microhardness increase coefficient of 37.6%. The parametric study of the residual surface hoop and axial stresses conducted via X-ray stress analysis shows that the STRB with near-optimal process parameters introduces significant residual stresses. STRB of the 2024-T3 Al alloy, implemented as a mixed burnishing process, produces a mirror-finish surface, improves the fatigue life by more than 2000 times, and increases the conventional fatigue limit by 35.1% compared to the reference condition.