Ball Burnishing Research Articles

Finite Element Analysis of Ball Burnishing on Ball-End Milled Surfaces Considering Their Original Topology and Residual Stress

Ball burnishing is a superfinishing operation whose objective is the enhancement of surface integrity of previously machined surfaces, hence its appropriateness to complement chip removal processes at the end of a production line. As a complex process involving plastic deformation, friction and three-dimensional interaction between solids, numerical solutions and finite element models have typically included a considerable amount of simplifications that represent the process partially. The aim of this paper is to develop a 3D numerical finite element model of the ball burnishing process including in the target workpiece real surface integrity descriptors resulting from a ball-end milled AISI 1038 surface. Specifically, its periodical topological features are used to generate the surface geometry and the residual stress tensor measured on a real workpiece is embedded in the target surface. Secondly, different models varying the effect of the coefficient of friction and the direction of application of burnishing passes with regards to the original milling direction are calculated. Results show that the resulting topology and residual stresses are independent of the burnishing direction. However, it is evident that the model outputs are highly influenced by the value of the coefficient of friction. A value of 0.15 should be implemented in order to obtain representative results through finite element models.

Surface Modification of Additively Manufactured 18% Nickel Maraging Steel by Ultrasonic Vibration-Assisted Ball Burnishing

Abstract The scope of this research is to characterize and optimize the vibration-assisted ball burnishing of additively manufactured 18% Nickel Maraging steel for tooling applications. We evaluate the suitability of vibration-assisted ball burnishing as an alternative method to post-process additively manufactured tool steel. To do so, we assessed a single pass post-processing technique to enhance surface roughness, surface micro-hardness, and residual stress state. Results show that ultrasonic burnishing after age hardening functionalizes additively manufactured surfaces for tooling applications creating a beneficial compressive residual stress state on the surface. The surface micro-hardness (HV1) varied between 503 and 630 HV1, and the average surface roughness (Ra) varied between 1.31 and 0.14 µm, depending on process parameters with a maximum productivity rate of 41.66 cm2/min making it an alternative approach to functionalize additively manufactured tool components.

The Effect of Ball Burnishing on Tribological Performance of 42CrMo4 Steel under Dry Sliding Conditions.

Ball burnishing appears to be a very promising approach for reducing surface height, generating compressive residual stresses and increasing hardness. Ball burnishing treatment was carried out using a Haas CNC Vertical Mill Center VF-1 equipped with the Ecoroll burnishing system. After burnishing, surface topographies of machined samples and hardness were measured. Wear tests were conducted using a ball-on-disc tribotester in dry sliding conditions. During tests, the friction force was monitored as a function of time. After tests, wear volumes were determined on the basis of surface texture measurements. Tests revealed that ball burnishing in most cases resulted in minimizing friction and wear of contacting elements.

Tool for Strengthening of the Component Surface Layers

The operational characteristics of metal components are often determined by the status of surface. In mechanical loading of solid bodies, the impact of the surface properties on formation and spreading of surface cracks is obvious, mainly as regards cyclic loading. Therefore, it is important to pay attention to knowledge of surface properties and their improvement.Cold plastic deformation is the easiest way to change the mechanical properties of the materials. The possibility of surface strengthening by ball or roller burnishing was found 80 years ago and since then has spread mainly into engineering and the automotive industry.In the authors’ workplace, experiments for surface layer hardening without ultrasound were realized with a newly developed device where the compressive force was applied statically, not dynamically. In the experimental part, we focused on the status of surface layers, especially the microstructure, hardness and roughness.

Monitoring of Processing Conditions of an Ultrasonic Vibration-Assisted Ball-Burnishing Process.

Although numerous references present the beneficial effects on surface integrity of ultrasonic vibration-assisted ball burnishing (UVABB), nothing has been reported about the dynamic behavior of the UVABB tool, workpiece, and machine triad during the process. In this paper, a dynamic monitorization through a set of 5 accelerometers is tested to analyze the interactions between the tool–workpiece–machine mechanical assembly. A UVABB tool attached to a milling machine and equipped with a piezoelectric stack that is able to assist the process with a 40-kHz vibration is tested on a milled C45 steel surface. First, the natural frequencies of the mechanical system are obtained through hammer impact tests. Then, the vibratory signals transmitted during the execution of the process are monitored and compared to those: two feed velocities and two burnishing preloads, all with and without vibration-assistance. Results show that the proposed accelerometer set is valid to assess the behavior of a UVABB process. The system’s natural frequencies are not varied by vibration-assistance and are not excited when the piezoelectric is functioning. It is confirmed that UVABB is safe for the machine and the tool, and there is no unexpected excited frequencies due to the piezoelectric excitation.

Effects of ball burnishing on surface properties of SKD11 mold steel

Burnishing is an energy-efficient technology to enhance the surface of mechanical parts. Metallic parts’ surfaces with hardness up to 65 HRC can be enhanced with a hydrostatic burnishing tool. This paper presents the effects of the hydrostatic burnishing on surface residual stress of the SKD11 mold steel by conducting the five-parameter orthogonal experiments using Taguchi Method. Results showed that burnishing force played the most significant role in the improvement of the magnitude of the compressive residual stresses, while the feed and the number of passes played less significant roles. Besides, the effect of burnishing direction and burnishing speed could be neglected. Single-factor experiments were conducted to provide further demonstrations of the influences of burnishing feed and number of passes on the surface properties and the results corresponded well with the orthogonal experiments in general. The single-factor experiments also showed that with the increase of burnishing feed, the surface hardness firstly experienced steady decrease and then decreased dramatically. However, the surface roughness firstly experienced steady increase and then increased dramatically. The surface hardness increased initially, but then followed a decreasing trend with the increase of the number of passes. The distribution of residual stress in the direction at an angle of 45° to the burnishing direction was related with the parity of the number of passes.

Analytical modeling and experimental verification of surface roughness in the ultrasonic-assisted ball burnishing of shaft targets

Ultrasonic-assisted ball burnishing (UABB) is a promising surface strengthening technology for improving the properties of components. This method superimposes ultrasonic vibration to the traditional deep rolling; it can improve the surface roughness of a material, enhance its surface hardness, and introduce a high compressive residual stress, thereby improving the fatigue performance of components. A mathematical model should be established to predict and analyze the relationship between the experimental process parameters and results and to predict the effect of UABB on surface roughness. In the present work, a mathematical model of surface roughness after UABB was established on the basis of Hertz contact theory, comprehensively considering the process parameters, dynamic vibration forces, and elastic rebound of the targets. UABB experiments were carried out to verify the correctness of the mathematical model. Results showed that UABB can significantly reduce the surface roughness of the material, and the values calculated from the derived mathematical model showed good agreement with the experimental findings. The surface roughness decreased with the burnishing force (50–250 N) and amplitude (4–10 μm) increased, whereas the feed rate decreased. The increases of radii of component and ball were detrimental to the improvement of the surface roughness. And elastic rebound was not conducive to roughness reduction and its influence was negligible. Finally, the derived surface roughness model can be used to predict the component values after UABB and understand the effects of machining parameters on the shaft targets during processing.

Effect of ball burnishing medium on the surface characteristics of free machining brass

Burnishing is becoming a promising surface finishing process to enhance materials surface properties. The control of the various process parameters yields the desired surface characteristics in brass materials. In the current work, free machining brass specimens were burnished by Abrasive Assisted Burnishing(AAB) process and Plain Burnishing (PB) process using ball burnishing tool. Response Surface Methodology was used to design the experiments in which Burnishing Force, Speed, Feed and Number of Passes were chosen as the process parameters. The minimum surface roughness achieved by PB and AAB was 0.1451 µm and 0.1041 µm respectively. The maximum surface hardness achieved using PB and AAB on the brass specimen was 207 HV and 248 HV respectively. The ball burnishing of free machining brass by AAB resulted in better surface characteristics as compared to the PB process.

Surface flatness and roughness evolution after magnetic assisted ball burnishing of magnetizable and non-magnetizable materials

• The proposed MABB tool can burnish also non-magnetizable and other materials. • Optimal roughness is at steel, aluminium and austenite steel but uncertain at polimer. • 20% hardness increase is at C45 steel and AA7075 aluminium, hardened thickness 0.3 mm. • The various burnishing strategies can increase and also decrease the flatness error. • Cycloid path is a compromise for roughness (micro-level) and flatness (macro-level) The burnishing process is applied to improve the surface roughness and hardness. The goal of the reported research was to evaluate the machining conditions on magnetisable and non-magnetisable materials by the novel permanent magnetic assisted ball burnishing (MABB) tool. The MABB tool was designed to reduce the surface roughness but this process has further effects on the surface C45 steel, X6CrNiTi1811 austenite steel, AA7075 aluminium alloy and PA6 polymer materials were burnished in the experiments. Surface quality is a complex feature that refers to the micro-geometrical characteristics of the machined surface. It includes roughness and waviness and gives a realistic picture about the top layer of the surface, while micro hardness and grains structure are especially important on sub-surface level. Results according to these analysed aspects mirrored that all of the tested materials can be burnished by the novel MABB tool, however, the effects from the economical viewpoints are diverse.

Investigation of Corrosion Resistance Enhancement for Biodegradable Magnesium Alloy by Ball Burnishing Process

Magnesium and magnesium-based alloys are considered ideal materials for implants in orthopedic treatment because their stiffness is close to that of human bones, and they can be absorbed gradually in the human organism. However, a major issue in their actual application is that the corrosion speed of Mg alloys is very high in aggressive environments such as the human fluids. In previous studies, many approaches have been attempted to enhance the corrosion resistance of Mg alloys. In this research, ball burnishing, a mechanical surface finishing process, is applied to improve the corrosion resistance of Mg alloys by changing its surface properties. The influence of the burnishing parameters on the corrosion resistance is investigated, and the corrosion of a treated and non-treated sample are compared. The test material used is the AZ31 Mg alloy. Firstly, a comprehensive review of the effect of burnishing on the final microstructures is reported. The influence of burnishing on grain size, work-hardened layer thickness, crystal orientation, and residual stress of the sample is discussed. Secondly, by conducting an especially designed long-term immersion test, the mass loss and surface evolution of each sample are evaluated. The experimental results indicate that, under proper processing conditions, the mass loss of the treated sample (8.8 mg) can be reduced to 36% of the non-treated one (24.2 mg). To elucidate the mechanism behind corrosion resistance enhancement by burnishing, the samples treated with the optimal processing parameters found are immersed in an aggressive solution for 1, 3, 5, and 7 days. From the results of mass loss measurement and surface structure characterization, it was found that, among pitting, general, and intergranular corrosion, pitting corrosion is the dominant corrosion mechanism. The holes enlarge because pits combine together, representing the greatest portion of mass loss. The main mechanism enhancing corrosion resistance is the size reduction of the grains on the surface induced by ball burnishing, causing a denser distribution of corrosion products in the immersion test. These corrosion products protect the material underneath accelerated corrosion.

Ball-burnishing factors affecting residual stress of AISI 8620 steel

Ball burnishing is a superfinishing operation performed to improve surface and subsurface integrity. In the present study, a model was developed to confirm that the ball burnishing of AISI 8620 steel affects its microstructures, roughness, and residual stress. As a part of the process, the influence of different parameters on the residual stress surface in the axial direction was investigated. Samples were prepared by heat treatment and turning. The ball-burnishing process was performed, and the improvements on the surface and subsurface integrity were found to be significant. Residual stress after ball burnishing was found to be affected by pressure and feed rate to a statistically significant extent. Stress was found to be in the form of compression. The steel displayed significant improvements in surface roughness and residual stress following burnishing. The linear regression models derived from the data for the relationship between burnishing factors and residual stress offer R2 values of 80.88%. Results suggest that the ball-burnishing process enhanced the properties of AISI 8620 steel.

The influence of ball and roller burnishing process parameters on surface integrity of Al 2024 alloy

Ball and Roller burnishing process is considered as one of the prominent cold working process among post machining operations used as surface treatment method for engineering materials in product design and manufacturing industry. This burnishing process mainly enhances the surface integral properties like compressive residual stresses, surface roughness (in microns) and surface hardness. The intent of this work is to design, develop a ball and deep roller burnishing surface treatment device and also to investigate the surface integral properties like residual stress, surface roughness and hardness of aluminium 2024 alloy before and after burnishing treatment process. The ball and deep roller burnishing process is carried out on aluminium 2024 alloy by varying process parameters like burnishing force, feed, number of burnishing tool passes. The results of experimentation shows that roller burnishing induces beneficial surface roughness, residual compressive stress and ball burnishing provides beneficial hardness.

Surface Texture Analysis after Hydrostatic Burnishing on X38CrMoV5-1 Steel

Ball burnishing is a plastic deformation process used as a surface smoothing and surface improvement finishing treatment after turning or milling processes. This process changes the surface stereometrics of the previously machining surface. Burnishing with hydrostatic tools can be easily and effectively used on both conventional and Computer Numeric Control (CNC) machines. The existing research of the burnishing process mainly focuses on the functional surface characterization, for example, surface roughness, wear resistance, surface layer hardness, etc. There is a lack of references reporting a detailed analysis of 3D parameters calculation with a mathematical model to evaluate the results of the ball burnishing. This paper presents the effect of ball burnishing process parameters with hydrostatic tools on the resulting surface structure geometry. The surface topography parameters were calculated using the TalyMap software. Studies were conducted based on Hartley’s static, determined plan. Such a plan can be built on a hypersphere or hypercube. In this work, a hypercube was used. In the case of Hartley’s plan makes it possible to define the regression equation in the form of a polynomial of the second degree. The input process parameters considered in this study include the burnishing rate, applied pressure, and line-to-line pitch. The significant influence of these parameters was confirmed and described as a mathematical power model. The results also showed a positive effect of hydrostatic burnishing on the roughness and geometric structure of the surface.

Effects of ball burnishing on the surface quality of Al 7075 alloy

Abstract The surface roughness of a part produced plays a critical role in influencing functional properties such as corrosion behavior, fatigue strength, and wear resistance. Therefore, it is very important to improve the surface roughness of Al 7075−T6 material, which is frequently used in the aerospace industry. For this reason, the finishing process, used to improve the surface quality of the parts in an easy, inexpensive and chipless manner, has recently become an interesting research topic. In this study, a ball burnishing apparatus was designed and experiments were carried out at different parameters (force, feed rate and number of passes) for the purpose of improving the surface quality of the parts. For the design of the experiments, the Taguchi method was used, thus saving time and cost savings and reducing the number of experiments required. Variance analysis (ANOVA) was performed and the effect contribution of the parameters on surface quality were obtained. As a result of the experiments, it was found that force, feed rate and the number of passes were important factors.

Investigation the influence of surface topography on scattering ability of aluminium reflectors from infrared quartz heater

Infrared (IR) heaters are used in many industries where heat treatment is required as well as in household appliances. One of the main problems with this type of equipment is non-uniform temperature field in the heating area, which results in a different degree of heating of the heated objects. In order to achieve greater uniformity of the temperature, some approaches are explored in practice, such as using embossed reflectors, mounting two or more heaters side-by-side, using emitter lamps with power controller devices, formation of gold or silver coatings, etc. The drawbacks of these approaches are complicating the design of the IR heaters, reducing the dimensions of heating area, increasing energy consumption, etc. Among the above-mentioned methods, the creation of a specific reflector surface topography is easily attainable and inexpensive technological approach. The main task of the present study is to investigate experimentally the influence of the specific patterns, obtained by ball burnishing process on scattering ability of the aluminium reflectors from infrared quartz heater.

Hardening effect and fatigue behavior enhancement through ball burnishing on AISI 1038

The objective of this paper is to present a comprehensive study of the effects of ball burnishing on the low cycle fatigue endurance of cylindrical specimens subjected to alternative bending stress, by constructing fatigue S-N curves to evaluate the impact of the process on the general fatigue behavior of AISI 1038. The specimens were burnished through five different force-number of passes couples, displacing the as-machined-material S-N curve towards higher lifespans as the degree of cold work is increased, either by effect of a higher force and more burnishing passes. The derived surface hardening effect also proved to be correlated analytically with the fatigue lifespan increase at all tested maximum-stress levels, as prove the correlation of the parameters that represent the potential equation associated to the Wöhler model with the hardening effect. It is concluded that the process performed with 120 N and 7 passes results in the most favorable results, represented by a 41% increase of hardness and a 77% increase in the lifespan in the best of cases.

Optimization of ball-burnishing process parameters on surface roughness, micro hardness of Mg–Zn–Ca alloy and investigation of corrosion behavior

In this work, optimization of ball burnishing parameters (depth of press, feed, burnishing force, number of passes) and their effect on surface roughness, microhardness and corrosion behavior of Mg-4%Zn-1%Ca alloy is investigated. The Taguchi optimization technique was used to determine the number of experiments and by considering S/N ratios, right combination of ball burnishing parameters were selected. Results obtained from the experiments were investigated and it is understood that depth of press, feed and number of passes have a significant effect on surface roughness, microhardness and consequently improves corrosion resistance of Mg-4%Zn-1%Ca alloy. From ball burnishing experiments it is deduced that there is large increase in microhardness of 107 Hv and surface roughness of 129 nm, achieved for the depth of press 0.45 mm, burnishing force 250 N, feed 450 mm min−1 and number of passes: 2. Corrosion behavior of the alloys were analyzed using potentiodynamic polarization and electrochemical impedance spectroscopy techniques in Hank’s balanced salt solution. The lowest corrosion rate was observed in DFN 442 sample (1.43 mm y−1) which is 4.7 times better than the homogenized alloy (6.73 mm y−1). It has been found that the ball burnishing plays an important role on surface roughness, microhardness and corrosion behavior of Mg-4%Zn-1%Ca alloy.

Ball Burnishing of Mg Alloy Using a Newly Developed Burnishing Tool with On-Machine Force Control

Burnishing is a surface finishing process, in which a very smooth surface finish is obtained by pressing a ball or roller against a machined workpiece. Additionally, owing to the surface plastic deformation caused by the movement of the hardened ball or roller, other surface properties such as hardness, fatigue life, and wear resistance can be improved. Burnishing force is one of the most important factors affecting the surface modification quality. However, methods for precisely monitoring and controlling the burnishing force are rarely investigated. In this research, a novel ball burnishing tool embedded with a load-cell and air-servo system was developed and fabricated for application to a CNC machining center. Using a specially designed control software, the burnishing force in the burnishing process was monitored in real time and controlled constantly and precisely by a force feedback system. Magnesium alloy AZ31 specimens were used to evaluate the performance of the developed system. The experiments were divided into two parts. In the first part, the effects of the processing parameters on the surface roughness were investigated. The results indicated that the surface roughness could be improved from Ra= 1.95 μm to Ra= 0.26 μm. In the second part, the effects of the burnishing parameters on the surface properties were investigated by conducting experiments using Taguchi’s orthogonal array. The results suggested that the burnishing force was the most significant factors affecting the surface hardness and grain size. The Vickers hardness could be increased from HV62 to HV149. The average grain size was reduced after the burnishing process, and a work-hardening layer thickness of 0.75 mm was achieved. X-ray diffraction results indicated that the crystal orientation was modified after burnishing, and the maximum measured compressed residual stress was 186.3 MPa in the tool feed direction and 87.8 MPa in the step over direction.

Surface hardening of 36 NiCrMo 6 steel by ball burnishing process

This work aims to characterize the 36 NiCrMo 6 steel in monotic traction. The tested samples were subjected to mechanical surface treatment (MST) by diamond ball burnishing. This process allow it possible to modify the physical and geometrical properties of the material. The stress-strain diagram obtained were processed and digitalised. The hardening domain was modelled and rational curves were established, taking into account the stresses triaxiality. Thus, the work hardening exponent of material considered was evaluated. The effect of ball burnishing on this exponent has studied in proceeding a comparative manner between burnished and machined surface. The results obtained show that by applying the optimal parameters for burnishing, the work hardening exponent of pre-machined surface layer can be increased by 10%, where nB = 0.407 (nT = 0.312 machined surface).

Experimental investigation on the ball burnishing of carbon fiber reinforced polymer

ABSTRACTThe polymer-based materials are generally used in all industrial applications. Even if polymer bars can be machined easily, they need surface finishing treatment after the machining process. The ductile properties make coarse roughness on the surface that causes the elastic structure of polymer materials. The carbon fiber reinforced composite materials differ from polymer-based materials by high strength and stiffness. Its structure exhibits similar performances such as metallic materials. The effect of ball burnishing on the surface quality of rod workpiece was investigated in this study. To enhance the surface quality of high strength carbon fiber reinforced polymer rod workpiece, burnishing process was performed in three different parameters (force, feed rate, number of passes) and under four different mediums (dry, wet, boron oil, and mineral oil) conditions. The results of the experiments were analyzed, and optimum burnishing parameters were determined and discussed in detail. The best surface roughness value of the CFRP material used in the experiments was obtained as burnishing force: 250 N, feed rate: 0.05 mm/rev, four passes and wet medium. According to the results of variance analysis, it was found that the CFRP workpiece is the important leading factor for surface roughness with a contribution ratio of 62.47%.