The objective of the research was to improve the wear resistance of titanium alloys by ball burnishing process. Burnishing process parameters such as burnishing speed, burnishing feed, burnishing force and number of pass were considered to minimize the specific wear rate and coefficient of friction. Taguchi optimization results revealed that burnishing force and number of pass were the significant parameters for minimizing the specific wear rate, whereas the burnishing feed and speed play important roles in minimizing the coefficient of friction. After burnishing surface microhardness increased from 340 to 405 Hv, surface roughness decreased from 0.45 to 0.12 μm and compressive residual stress were generated immediately below the burnished surface. The optimization results showed that specific wear rate decreased by 52%, whereas coefficient of friction was reduced by 64% as compared to the turned surface. The results confirm that, an improvement in the wear resistance of Ti–6Al–4V alloy has been achieved by the process of ball burnishing.

Wear resistance enhancement of titanium alloy (Ti–6Al–4V) by ball burnishing process

Influence of low-plasticity ball burnishing on the high-cycle fatigue strength of medium carbon AISI 1045 steel

Effects of pre-treatments on aging precipitates and corrosion resistance of a creep-aged Al–Zn–Mg–Cu alloy

In this article, the ball burnishing is applied on sculptured surfaces, aiming at enhance surface roughness. Different strategies are possible for burnishing, the continuous burnishing (CB) which uses a five-axis interpolation of the machine tool, and the patch burnishing (PB) using a more simple 3 + 2 axis interpolation. Using both techniques complex parts are burnished and a big improvement in surface roughness achieved, but some differences between both approaches appear. Two parts have been previously machined in a five-axis milling center and finished using the ball burnishing approaches. The first one is a steel AISI 1045 with a hemisphere shape, whose geometry is simple. The second one is a steel DIN 1.2379 part (64 HRC), with more complex features. Surface quality was evaluated for both burnishing approaches, obtaining significant improvements on surface roughness and hardness. The main general conclusion is that ball burnishing reduces roughness without penalizing the manufacturing time or surfac...

Five-Axis Machining and Burnishing of Complex Parts for the Improvement of Surface Roughness

Cold expansion technology of connection holes in aircraft structures: A review and prospect

Enhancement of the wear resistance of CuAl9Fe4 sliding bearing bushings via diamond burnishing

Diamond burnishing is a surface modification method aimed at improvements in the surface integrity (SI) and operating behavior of metal components. A cost-effective optimization approach for increasing the fatigue strength of diamond-burnished steel components has been developed. The basic idea is that the fatigue strength can be controlled by controlling some of the SI characteristics (surface micro-hardness, hardened-layer depth and roughness) whose measurements are not time-consuming and expensive. Thus, a multi-objective optimization task was set and solved using the weight vector method. The governing factors were the diamond radius and burnishing force. The resulting fatigue limit differed from the maximum fatigue limit by a mere 0.44%, which proves the effectiveness of the proposed approach. The results obtained for the fatigue limit are explained by means of an X-ray analysis of the introduced residual stresses and an analysis of the microstructures of the surface and subsurface layers. It has been established that a greater depth of the affected zone coupled with a smaller gradient in the alteration of the microstructure in depth provides larger fatigue strength.

A cost-effective optimization approach for improving the fatigue strength of diamond-burnished steel components

The article presents a theoretical-experimental approach developed for modeling the coefficient of sliding friction in the dynamic system tool-workpiece in slide diamond burnishing of low-alloy unhardened steels. The experimental setup, implemented on conventional lathe, includes a specially designed device, with a straight cantilever beam as body. The beam is simultaneously loaded by bending (from transverse slide friction force) and compression (from longitudinal burnishing force), which is a reason for geometrical nonlinearity. A method, based on the idea of separation of the variables (time and metric) before establishing the differential equation of motion, has been applied for dynamic modeling of the beam elastic curve. Between the longitudinal (burnishing force) and transverse (slide friction force) forces exists a correlation defined by Coulomb's law of sliding friction. On this basis, an analytical relationship between the beam deflection and the sought friction coefficient has been obtained. In order to measure the deflection of the beam, strain gauges connected in a “full bridge” type of circuit are used. A flexible adhesive is selected, which provides an opportunity for dynamic measurements through the constructed measuring system. The signal is proportional to the beam deflection and is fed to the analog input of USB DAQ board, from where the signal enters in a purposely created virtual instrument which is developed by means of Labview. The basic characteristic of the virtual instrument is the ability to record and visualize in a real time the measured deflection. The signal sampling frequency is chosen in accordance with Nyquist-Shannon sampling theorem. In order to obtain a regression model of the friction coefficient with the participation of the diamond burnishing process parameters, an experimental design with 55 experimental points is synthesized. A regression analysis and analysis of variance have been carried out. The influence of the factors on the friction coefficient is established using sections of the hyper-surface of the friction coefficient model with the hyper-planes.

http://www.techno-press.org/download.php?journal=csm&volume=4&num=4&ordernum=1

Modeling of the friction in the tool-workpiece system in diamond burnishing process

Bolted joint railroad is the subject matter of this paper Rail joint elements are subjected to cyclic and impact loads as a result of the passage of trains, which causes the origination and growth of fatigue cracks occurring, in most cases, around the bolt holes Fatigue failure around rail-end-bolt holes is particularly dangerous because it leads to derailment of trains and, consequently, to inevitable accidents Moreover, the cracking at rail-ends, which starts from bolt hole surface, causes premature rails replacement The presence of residual compressive hoop stresses around the bolted holes, which is achieved by prestressing of these holes, extends the fatigue life of bolted joint railroads This article presents an innovative technology for pre-stressing of rail-end-bolt holes, implemented on a vertical machining centre of Revolver vertical (RV) type Two consecutive operations are involved in the manufacturing technology process: formation of the hole by drilling, reaming and making of a chamfer t

A new approach for pre-stressing of rail-end-bolt holes

Slide burnishing (SB) is a simple and efficient method for finishing symmetric rotary metal parts. The thermo-mechanical nature of SB has not been studied in the literature and is, therefore, an object of investigation in this article. A combination of finite element method (FEM) analyses and experiments is used, and a very important part of building the FEM model is the constitutive model of the surface layer of the workpiece being slide burnished. A temperature-dependent, nonlinear kinematic/isotropic hardening material constitutive model of the surface layer of 37Cr4 steel has been modelled on the basis of temperature-dependent indentation tests and inverse FEM analyses. In order to illustrate the benefits of this thermo-mechanical constitutive model, 3D FEM simulations of the SB of holes have been conducted; doing so establishes the effect of the generated temperature on the residual hoop stress distribution around the processed hole. Fully coupled thermal stress, sequentially coupled, and temperature-independent FEM simulations have been conducted to determine the residual hoop stresses. Alternatively, these stresses are experimentally obtained through the modified “split ring” method. It has been proven that a sequentially coupled thermal stress FEM simulation with nonlinear kinematic/isotropic hardening predicts the residual hoop stresses in such a manner as to be in satisfactory agreement with the experimental outcomes. It has been established that the generated temperature reduces the beneficial effect from the introduced residual stresses, thus reducing the fatigue life of the corresponding structural component.

A Temperature-Dependent, Nonlinear Kinematic/Isotropic Hardening Material Constitutive Model of the Surface Layer of 37Cr4 Steel Subjected to Slide Burnishing

G. V. Duncheva

Papers

Enhancement of the wear resistance of CuAl9Fe4 sliding bearing bushings via diamond burnishing

A cost-effective optimization approach for improving the fatigue strength of diamond-burnished steel components

Modeling of the friction in the tool-workpiece system in diamond burnishing process

A new approach for pre-stressing of rail-end-bolt holes

A Temperature-Dependent, Nonlinear Kinematic/Isotropic Hardening Material Constitutive Model of the Surface Layer of 37Cr4 Steel Subjected to Slide Burnishing