Nanostructuring burnishing is an effective and mature process for enhancing the surface properties of metallic workpieces. Through severe mechanical deformation, nanostructuring burnishing forms a very hard and smooth surface layer that improves the wear resistance and other properties of the workpiece. This surface treatment requires careful control of process conditions, as the application of large forces and sliding velocities can easily damage the workpiece either through overheating or self-excited oscillation, resulting in an uneven surface. In this paper, we investigate one possible source of such instabilities, namely, unstable stick–slip motion in the sliding direction. When combined with the coupling of normal and tangential stresses through the von Mises yield criterion, the resulting fluctuations of the coefficient of friction can temporarily decrease the effective indentation hardness in the normal direction and thereby produce an uneven indentation track. A dynamical model based on this mechanism is investigated numerically, and the results are found to be in qualitative agreement with experimentally observed surface irregularities encountered in the burnishing of a long drive shaft. The influence of the local bending stiffness at various points along the shaft is also taken into account.

This article demonstrates a multi-step process for forming a nominally flat surface with circumferential lubricating microcavities on a tribological assembly of an & KHcy;38CrSi steel shaft. The process includes finish turning, preliminary strengthening burnishing, deformation profiling of microcavities by a honing stone and smoothing of microprotrusions. The study determines the optimal technological parameters for each of the transitions based on microhardness and oil absorption power maximization, as well as roughness and periodic impact minimization. The process optimization is conducted using the Tagichi experiment design method. The optimal combination of technological parameters for hardening burnishing was discovered to be: normal force F = 200 N; feed rate f = 0.025 mm/rev and three tool passes. These burnishing parameters practically eliminate the influence of periodic impacts at spatial frequencies determined by the tool feed rate and the number of spindle rotations during turning. We determined suitable honing stone grit parameters and application force that yield microcavities 3.8 to 8.1 mu m in depth, as well as the optimal parameters for smoothing of microprotrusions, resulting in a bearing area roughness of Sa = 0.15 mu m and oil absorption power of 13.7410(-5)mm(3)/mm(2).

The influence of implant design and structural factors on fatigue life under cyclic loading was investigated. The implants were manufactured from 316L steel powder using 3D printing for medical use. A simulation model of implant deformation was built using ANSYS software. The obtained data showed that the geometry of the implant had the necessary margin of safety for osseointegration time. It was found that the stress concentration factor, which is associated with fatigue life, for an implant with a hexagon head and internal thread depends on the mechanical properties of the metal, design, and load conditions. The presence of internal threads and holes in the implant increases the stress concentration factor by more than 10 times. The number of load cycles for the failure of the implant, which was calculated by taking into account a coefficient for reducing the endurance limit, was found to be sufficient for implant osseointegration.

The paper presents the results of experimental studies of the AISI 304 steel disc surface after finishing turning, electropolishing and nanostructuring burnishing after one and five passes of the tool with a natural diamond tip with a radius of 2 mm. It is shown that surface layer nanocrystallization provides for almost complete decomposition of austenite in a layer up to 100 µm thick, an increase in microhardness up to 400...450 HV0.025 and a 3.3-fold reduction in the wear intensity on hardened AISI 1045 steel under conditions of lubrication with industrial oil compared with electropolishing. The content of residual austenite in the surface layer is not more than 5% when the temperature rises to 400°C.

This article is devoted to the development of a sliding burnishing scheme using a flat cylindrical indenter. The previously established patterns of nanostructured state formation in the AISI 52100 steel subsurface layer showed a need to create a special tool with a variable tilt angle of the indenter and with force regulation. A new tool with a cubic boron nitride indenter opens wide possibilities for nanostructuring burnishing of hardened bearing steel. Firstly, a flat cylindrical indenter has high durability due to repeated rotation around its axis. Secondly, the change of the tilt angle to the treated surface allows controlling the contact compression pressure and plastic shear deformation, which determines the formation of a nanostructured state of the material by the method of severe plastic deformation (SPD). The purpose of the work is to determine the optimal parameters of the process and tool in order to form a nanostructure and significantly increase surface layer microhardness. The goal was achieved by the methods of finite element modeling (FEM) and experimental studies of burnishing when the indenter tilt angle changes from 0.5° to 2.5° under dry processing conditions. Numerical simulation of the process made it possible to establish optimal values of the indenter tilt angle of 2° and the burnishing force 250 N according to the criteria of maximum contact pressure and cumulative deformation. The experimental studies of cumulative deformations and the coefficient of friction by the method of burnishing a split disc and dynamometry of the process confirmed the FEM results. The transmission microscopy, durometry, and 3D surface profilometry showed the sensitivity of nanocrystallite sizes, microhardness, and roughness to an indenter tilt angle and confirmed the optimality of the established tilt angle value.

The effect of heat treatment modes of tool steel Fe – 12% Cr – 0.8% Mo – 0.9% V – 1.6% C on its structure and strength is analyzed. The temperatures for quenching and tempering providing maximum hardness and strength and satisfactory ductility are determined.

The article probes into a relationship of the shear strain intensity and the shear strain rate in the surface layer and the sliding velocity of a spherical indentor and its loading repetition factor. It brings forward an experimental procedure to evaluate the shear strain intensity and rate by analyzing the geometrical parameters of the bulge of plastically edged metal and the thickness of the shifted layer relative to different sliding velocities and feed rates.

An optimal condition for implant osseointegration is its mechanical stability. However, the process of osseointegration depends on numerous other conditions: mechanical stimulation, implant specific geometry, chemical composition of the surface and its architectonics, topology, and the way of surface relief formation.The aim of the investigation was to assess the capabilities of osseointegration of implants from stainless steel, fabricated by means of additive manufacturing technologies, for rabbit tibia replacement.Materials and methods. The experiment has been carried out on 6 chinchilla rabbits aged 6-8 months. Amputation of the shin was performed to all animals under general anesthesia, and implants, made with the help of additive manufacturing technologies, were screwed in. The stumps, abutments and implants were fixed during 6 weeks by Ilizarov apparatus. Investigations were performed using clinical, radiographic and histological methods.Results. The findings obtained testify to the ability of the applied screw construction to osseointegration into the tubular bone structure. Neogenesis of bone tissue on the implant surface after 12 weeks provides formation of a bone-implant block ensuring stable implant position in the tubular bone and capability of enduring mechanical load.

Relevance The work deals with the challenging problems of improving the function and aesthetic appearance of the finger stumps using a surgical technology of osseointegration. Purpose To present preliminary results of osseointegration with the use of titanium implants and exoprostheses for finger stumps. Material and methods Osseointegration was performed in order to improve the function and aesthetic appearance of 17 phalangeal finger stumps in 8 patients at the age of 15 to 57 years who underwent treatment at the FSBI RISC for RTO of the RF ministry of health in 2014. Results Osseointegration that was assessed with clinical and radiographic methods, bench tests, and DASH scale resulted in positive short-term outcomes. Conclusion Osseointegrated finger prostheses for defects at the phalangeal level improve hand functions and appearance within a short period of time. The method of osseointegration is strategically important for management of large limb segment amputations and high levels of truncation. It is relevant to develop domestic implants that will optimize treatment terms, its results, and further prosthetic application.

In the paper the influence of friction-induced adhesion of metal to the tool on the formation of surface topography under nanostructuring burnishing was studied. A comprehensive approach, including both experimental (optical microscopy and profilometry) and theoretical (computer-aided simulation) methods was used. The results showed a direct connection between values of adhesion strength of materials in contact with the workpiece surface pattern quality caused by the tool movement. Results of the experimental and theoretical study are in good agreement and allow us to identify the reason of regular profile forming during surface burnishing.

The development of personalized medicine throughout the world is linked with advances in basic sciences such as genetics and biochemistry. This relates primarily to the creation of technologies for targeted highefficacy treatment of cancers. The potential for fast and accessible individualized preparation of medical devices, medicines, and even organs has appeared with the application of 3D printers to medicine. Could the personalized approach to making osteointegrated implants for traumatology and orthopedics lead to the development of hightech products based primarily on additive technologies? And would customized implants be able to improve the care of patients requiring surgical treatment? Answers to these questions require close interaction between surgeons, healthcare administrators, materials engineers, and technologists. And even if we gain an understanding of the needs, implementation of projects of this type will involve legal and economic conditions whose complexity could well become a barrier to their introduction.

The article considers the problems of the mathematical modeling of thermal physics of the tool for nanostructuring burnishing. Physical and equivalent heat diagram of the system are developed. On the basis of the equivalent heat transfer diagram, the equivalent circuit and the system of equations of the mathematical model are created. The dependence of the tool indenter tip temperature on cooling system thermal parameters is obtained. The comparison of efficiency of heat removal from the tool indenter when using the developed two-circuit cooling system and the system supplying lubricant cooling liquid through the lathe centre spindle, as well as when applying nanostructuring burnishing without cooling is carried out.

The stress and strain distribution during surface treatment is determined by a variety of factors which can be controlled by changing the process parameters. A novel approach to improving the service quality of working metal surfaces is nanostructuring burnishing, which allows for improving not only surface roughness but also hardness and other physico-mechanical characteristics of metallic materials. Each of the technological parameters has its own specific contribution to the deformation-induced structural evolution during nanostructuring burnishing. A challenge is to find few integral governing parameters responsible for the quality of surface modification. To achieve this goal we carried out numerical studies to determine the effect of process parameter variation on the subsurface characteristics.

Numerical modeling of nanostructuring burnishing has been carried out to reveal the limiting values of process parameters, which serve both to provide the appropriate surface quality and positive deformation-induced structural modification of the subsurface layers as well as to avoid shear instability in the subsurface layers of burnished metal. The effects of load, burnishing speed, tool pass number and tribological transfer on the burnished surface roughness have been elucidated by the example of quenched and tempered steels 20X (EN 20Cr4). It was shown that overloading results in quasi-viscous flow of the subsurface material, deterioration of the surface and ruining the positive effect of nanostructuring burnishing.

It is well known that the burnishing process affects the surface characteristic, namely: surface roughness, surface hardness, wear resistance, fatigue resistance and increased maximum residual stress in compression. Unfortunately we still far from full understanding what parameters and mechanisms are responsible for the certain surface modification. That is why methods of computer modeling can be considered as useful tool to investigate surface changing during contact interaction as well as burnishing process. It is more essential if we consider processes are taking place at atomic scale level.In the paper we try to reproduce the details of burnishing process at nano-scale level. To investigate features of surface treatment we use the molecular dynamics simulation. Various pure crystalline materials were considered. Results of our modeling are very close to the experimental observation