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The surface texture characteristics are specified by international standards, which include dozens of parameters, basically geometrical. The probability of filling the rough surface layer with a material from the reference line and through the layer thickness is proposed as a quantitative roughness assessment. It takes account of geometrical parameters, shape, height and frequency of surface irregularities. An example is given of studying a surface with processing defects, and a comparative analysis of surface treatment methods is presented. The calculation results are summarized in a table of probabilistic characteristics of surfaces for various processing methods.

A new technological practice for the formation of a regular surface topography by means of oscillating ironing is presented. The results are based on analytical calculations and experimental studies. Surface topography after oscillating ironing depends on workpiece rotation frequency, deforming tool advance, oscillation frequency, deforming tool amplitude and tilt angle. The influence of the oscillating ironing process parameters on the size and shape of contact patch is confirmed.

Material enhancement plays an important role in everyday life due to its impacts on the quality of goods, which we, consumers, buy and use. Answering these questions is critically important for gaining deep and insightful understanding of both new plastic deformation processes, such as, for example, incremental plastic deformation, shoot peening, nano-burnishing, wide burnishing, and low plasticity burnishing, as well as traditional plastic deformation processes, such as extrusion, drawing, and bending. The Coulomb friction coefficient µ and the constant friction factor m appear to be independent of the dimension ratio and are influenced mostly by roughness, and they range from µ = 0.363 (with lubricant) to µ = 0.488 (without lubricant) and from m = 0.726 (with lubricant) to 0.99 (without lubricant). [Extracted from the article]

Burnishing, the plastic deformation of the workpiece surface due to sliding contact with a tool called burnisher, is a finishing operation widely used in various industries. In this work, impacts of the initial surface roughness Ra of the workpiece being burnished, the nature of friction in the contact zone, and the clamping force on the stability and energy efficiency of burnishing have been investigated. Experiments have been conducted with and without lubricant, represented by low-viscosity deep-hydrogenated fraction of sour oils, at initial surface roughness Ra of 0.8 and 1.25 μm and variable (100–200 N) clamping force. A key process indicator, which largely controls mechanics of burnishing, the temperature in the tool-workpiece contact zone has been measured using natural thermocouple method. Microhardness of the workpiece surface after burnishing has also been measured. It has been shown that changes in the temperature of the tool-workpiece contact zone are proportional to the changes in the squared tool clamping force. This dependence appeared to be universal and equally applicable to burnishing with and without lubrication. Based on the analysis of the experimental data, a new criterion of the burnishing efficiency has been developed. The new criterion simplifies the choice of optimum operational parameters and helps in preventing adverse impacts of structural phase transformations in the workpiece surface layer that unavoidably lead to reduced product quality and operational reliability and in reducing tool wear, which is critically important in the case of dry burnishing. The obtained results show that the nature of friction accompanying the surface plastic deformation has a significant impact on the stability and energy efficiency of the burnishing process. While the clamping force is equally important for burnishing with and without lubrication, the initial roughness Ra has an impact on dry burnishing only. Application of minimum quantity lubrication (MQL) under experimental conditions typical for industrial burnishing is found to be favorable. In particular, it was shown that MQL not only enhances the stability of burnishing process and but also increases its energy efficiency by more than 20%. [ABSTRACT FROM AUTHOR]

The combined Coulomb constant shear friction law is widely used in commercial and research software for the finite-element analysis (FEA) of metalworking and is naturally more flexible and hence, more relevant to real-life manufacturing than the individual Coulomb and constant shear friction laws. In this work, a new mathematical model of coefficients in the Coulomb constant shear friction law for extruding a metal through narrow V-shaped channels with small convergence angles has been developed and evaluated and compared with laboratory measurements. The extrusion of the model material (lead) through narrow V-shaped channels with small convergence angles varying from 0 to 3.5 degrees has been studied. The Coulomb friction coefficient µ and the constant friction factor m appear to be independent of the dimension ratio and are influenced mostly by roughness and range from µ = 0.363 (with lubricant) to µ = 0.488 (without lubricant) and from m = 0.726 (with lubricant) to 0.99 (without lubricant). The relative length dominated by the Coulomb friction law is less than 1%, and the Coulomb's coefficient of friction can be approximated as ½ the constant shear friction factor for all tested cases. The developed method and algorithm can be used in both FEA of manufacturing processes and efficiency tests for lubricants used in metalworking. [ABSTRACT FROM AUTHOR]

Bimetallic materials are important in many industries (aerospace, medicine, etc.) since they allow the creation of constructions that combine specific functional properties, for example, low density (aluminum alloy) and high corrosion resistance (stainless steel), due to layering fabrication of the bimetallic joint. On the other hand, the difference in thermophysical properties of the dissimilar material layers leads to residual stresses, which cause deformation and destruction of such a bimetallic joint produced via the methods of surfacing or additive technologies. This article discusses the methods based on the gray relational analysis and generalized desirability function for the quality assessment of Al–10Si–Mg aluminum alloy and Cr18–Ni10–Ti stainless-steel bimetal fabricated via selective laser melting (SLM). There are four main parameters (quality indices) of the quality generalized assessment, which determine the degree of Al penetration into the steel substrate and Fe into the deposited layer, the difference in microhardness values on both sides of the interface boundary, and the resistance to mechanical destruction of the bimetallic joint. According to the results obtained, the best set of quality indices corresponds to the SLM technological modes with an energy density of 105 and 147 J/mm3. The greatest functionality of the bimetals is determined by the quality index associated with its strength. Therefore, methods of gray relational analysis and desirability function make it possible to form a generalized assessment for the bimetallic joint quality and, consequently, to select the best technological mode. [ABSTRACT FROM AUTHOR]

Processing technology using productive surface plastic deformation (SPD) was developed and is known as "wide burnishing" (WB). The mechanics of new WB technology differs from classic SPD technologies (rolling or burnishing). For example, force, applied during burnishing, is equal to 150–300 N, but for WB it is equal to 2500–5000 N due to implementing this process in mass production, characterized with limited processing time (3–4 turns of the work piece). WB also has a high degree of deformation due to a multiple deformation passes. An analytical study of burnishing with the upper bound approach method energy-force parameters was carried out. Its results were compared with the results of finite elements analysis in Deform 2D and with experimental data. Field of reasonable burnishing parameters, assuring minimum surface roughness, was determined experimentally. [ABSTRACT FROM AUTHOR]