Papers by Keyword: Burnishing

Abstract: Burnishing, which is one of the most powerful processes for microstructural evolution, was performed by a cemented carbide ball (6 mm in diameter) that was loaded and fed on the flat surface of a rotating disk specimen of carbon steel using a lathe machine. The effects of burnishing process parameters such as force and rotation speed on the surface roughness, microstructure and hardness were investigated. In addition the dry sliding wear properties of the burnished surface layers were studied using a ball-on-disk friction method. It was found that the burnished surface was much smoother than as-turned surface (before burnishing) owing to the plastic flow of the surface asperities through the rubbing motion of the burnishing ball. Nanostructure in the 30 - 50 nm grain size range was formed in the burnished sub-surface layer, and the hardness significantly increased due to the grain refinement. The nanocrystalline microstructure was observed at high burnishing forces and speeds owing to the high strain and strain rate of the friction-induced plastic deformation. Moreover the burnishing process reduced the specific wear rates by a factor of six. Thus we concluded that the wear resistance of carbon steel can be significantly improved by burnishing due to the smooth surface and nanostructured sub-surface layers.

Abstract: In this study, a polycrystalline composite diamond (PCD) was adopted instead of a single crystal diamond as a burnishing tool. At first, EDM machinability was compared between two kinds of PCDs (10μm grain size), i.e. standard PCD (S-PCD) and electrically conductive PCD (EC-PCD (which was made of boron doped diamond particles). EDM machining time to make a hemispherical shape was 17 minutes for EC-PCD and 37 minutes for S-PCD. Further experiments were conducted with EC-PCD of different grain sizes such as 2μm and 5μm. As a result, the smaller the grain size of EC-PCD the higher the machining efficiency was. Surface roughness values of the EC-PCD after finish EDM were Rz=1.7μm for EC-PCD010, Rz=1.4μm for EC-PCD005, and Rz=1.2μm for EC-PCD002. As a result of burnishing a carbon steel bar (S45C, φ30mm) with the EC-PCD tool, the surface roughness value after machining was improved from 10μm to 1μm.

Abstract: The scheme for the wave strain strengthening of inner cylindrical surfaces diameter up to 100 – 120 mm is offered. One-ring and multi-ring drifts, bolls of various diameters are used as a tool. The effectiveness of a dynamic influence upon the center of deformation is considerably higher than that of the static one used during common burninshing. At the same time the share of power spent for the plastic deformation increases and power intensity drops, and technological possibilities of the process become wider. The experimental research of wave deformation strengthening at different diameters of openings in bushes with different wall thickness revealed that the process is realized in a wide range of tightnesses from 0.5 to 3 mm which is necessary to choose taking into account the wall thickness, and strengthening embraces the whole wall thickness (up to 20 mm) under certain conditions. A considerable decrease of roughness height parameters of the strengthened surface and profile bearing length increase are established. The formation of oil pockets takes place on a surface worked as a consequence of kinematic peculiarities of the wave strain strengthening that contributes to wear resistance increase of friction couples. The productivity of wave strain strengthening exceeds the productivity of common burnishing more than twice, and there appears a possibility to exclude the operations of finishing abrasion with unfavorable technological heredity from the engineering procedure.

Abstract: New trends appeared in product design and technological planning, which contributed in the development of new finish machining procedures like diamond burnishing. With the influence of diamond burnishing process, the surface roughness, the hardness of machined surface, and the dimensional accuracy can be improved. In this paper the effect of burnishing technological parameters on the cylindricity error of the burnished cylindrical surface and furthermore on changing of hardness of the burnished surfaces were examined, too. Burnishing parameters, which were taken into consideration during the examinations, are burnishing speed, burnishing feed, and burnishing force. Formulas suitable for determination of the improvement ratios of cylindrical shape error and improvement of hardness were determined by the Taguchi type Factorial Experimental Design.

Abstract: A traveling sphere by an elastic cylinder surface boundary problem is considered. At a contact zone the friction force and adhesive bond areas are supposed. The received solution enabled to estimate a plastic deformation area. The experimental and calculation data comparison found the acceptable accuracy of plastic deformation depth estimation. The devised methodology makes it possible to estimate the radius joining points depth of the plastic deformation by sphere.

Abstract: As a measure to perform a burnishing process easily on an NC lathe, the authors propose a new method using a flank face positioned in a few millimeters lower part of the nose cutting edge of a tool. In the experiment, giving a fixed depth of burnishing (t=1, 2 and 4μm/pass), the carbon steel workpiece (S45C) of φ30mm which had been turned at V=200m/min and f=0.15mm/rev was burnished by predefined number of times. As a result, the surface roughness improved in nearly proportion to the total depth of burnishing and the roughness value of Rz≈10μm measured after turning could be improved to Rz≈2.5μm. Utilizing the feed control with an accuracy level of micron meters of the NC lathe, an attempt to control the dimensional accuracy of the workpiece diameter in the order of micron meters was also made. As a result, the workpiece radius came down constantly by 0.6~0.8 times in proportion to the tool depth of burnishing (t=1μm/pass), which reveals that the dimensional accuracy of the workpiece diameter could be controlled by the proposed burnishing process utilizing a fixed depth of burnishing system. Using the same burnishing process, circularity of the workpiece Δr could be improved to Δr≈2μm from Δr≈4μm measured after turning.

Abstract: In this paper the way to numerical modeling of surface details after finishing is examined. Feature of the presented model is a sequence in the simulation results: at the beginning surface is modeled after processing by grinding and only then topography is modeled after burnishing. Simulation of a burnishing tool on close to real surface but not on the perfect surface allows considering the effect of technological heredity, which is important for the engineering manufacture.

Abstract: The surface of the finishing machined parts is defined mainly by roughness parameters. Growing demands on the part, especially mating sliding or rolling, require the specification of additional parameters, such as waviness parameters, particularly when there is significant resistance to seizing or noise reduction. This paper presents surface waviness characteristics of hardened burnished steel.

Abstract: Angular momentum pumps are very often applied on-board ships. These pumps are used in cooling circuits of medium and high power engines, power plant boilers and in bilge, ballast and fire installations. Very extensive use of angular momentum pumps on board is linked with their numerous advantages. During operation, the wear of the marine hull, the rotor and the shaft seals takes place. The research attempts to increase the service life of shafts. The article presents the research results referring to the analysis of the influence of finish treatment (turning, grinding and burnishing) on the corrosion properties of steel applied to marine pump shafts. The research was performed on a roller of 40 mm in diameter made of X5CrNi18-10 (AISI 304 L) stainless steel. The turning process was carried out by means of a WNMG WF 080408 Sandvik Coromant cutting tool with replaceable inserts. The grinding process was performed by grinding attachment for lathes. The 1 – 80×10×32 – 99C 80-N V grinding wheel was used for the process. The process of burnishing was done by SRMD burnisher from Yamato. In addition, the influence of the burnisher passes number on the corrosion properties was determined. The paper will present the results of electrochemical impedance spectroscopy and potentiodynamic research. To conduct the survey, the Atlas 0531 EU & IA potentiostat was used. Determination of the corrosion process parameters was performed by the computer programs: AtlasLab 2.0, EIS Spectrum Analyzer and Elfit2.

Abstract: The study summarises the results of the analysis of the diamond burnishing process. The subject of the analysis was whether the diamond burnishing can be done with the use of the type of lubricating material which hardly pollutes the environment. Of course, we used conventional oil for lubrication as well, which served as base data. The effectiveness of the process was examined by analysing the surface roughness when changing the technological parameters such as burnishing speed, feed, and burnishing force. Besides examining the parameters of surface roughness we examined the improvement ratio of surface roughness as well as the function of burnishing technological parameters. The empirical formula for determination of the improvement ratio of surface roughness was determined by the use of factorial experimental design.