Papers by Keyword: Roughness

Abstract: The article describes the orthogonal turn-milling technology applied for powder high speed steels. The cutter with carbide inserts was used in the experiments. The orthogonal turn-milling model was developed to improve the surface quality by choosing optimal cutting modes based on the simulation results. The mathematical model makes it possible to predict geometric surface deviations. The impact of cutting speed, tool feed and radial depth of cut on the geometric surface parameters was identified. The results make it possible to achieve the satisfactory level of surface quality without deteriorating the machining productivity. The avenues for further research are outlined.

Abstract: In order to understand the contribution of various metals in the formation of ohmic contacts, Ni/Al/Ti ohmic contacts on n-type 4H-SiC in terms of a different annealing temperature and Ti composition are investigated, which is more difficult to form than p-type ohmic contact. The formation of the Ni/Al/Ti metal alloy system is much more sensitive to metal composition than annealing conditions. With the increase of metal composition, the contact with a high Ti content yields a lower specific contact resistivity compared with the low Ti contact. The annealed surface morphology and phase resultants were examined by scanning electron microscopy (SEM) and atomic force microscope (AFM), respectively. With the increase of Ti components, the surface morphology of the samples becomes more uniform and smoother, while the surface roughness remains unchanged. It implies that Ti metal can not only reduce the ohmic resistance, but also protect the surface of the sample and maintain the roughness.

Abstract: Currently the measurement of surface texture in mechanical engineering is traditionally carried out using profilometers. Modern profilometers do not allow measuring of surfaces with complex shapes. This is due to the different sensitivity of the sensor and the discreteness of the movements along the axes of the Cartesian coordinate system. Coordinate Measuring Machines are devoid of such a drawback. However, stylus of the coordinate measuring machine has a diameter many times larger than the diamond stylus of the profilometer. Therefore, there is a mechanical filtering effect, that affects the results of measuring the parameters of the surface texture. In this paper a mathematical model of the contact of the spherical stylus and a rough surface based on analytical geometry is proposed. Influence of the diameter of the spherical stylus on the maximum measurement errors of a amplitude parameters are investigated. Seven amplitude parameters Rp, Rv, Rz, Ra, Rq, Rsk, Rku of the surface texture are modeled. Coordinate measuring machine and profilometer with stylus diameter of 2 μm measurement results are compared. it was concluded that the stylus diameter of the coordinate measuring machine when measuring the surface texture should be no more than 20 μm.

Abstract: There are results of studying the parameters of the indenter contact interaction with the surface when processing cylindrical parts made of 45 steel of different hardness by surface plastic deformation (SPD) methods with single-indenter elastic tools (diamond burnishing, ball burnishing). There were considered such characteristics as the resistance force when the indenter starts and in the steady state of SDP, the range of force fluctuations during processing, friction factor when the indenter starts and in the steady state, as well as some derivative coefficients. Adequate physical-statistical models for the quantitative estimation of the contact interaction parameters from SPD processing factors are obtained.

Abstract: One of the fundamental tasks in restoring the operability of cylinder liners is the application of a composite coating with a predetermined microhardness value. The authors have developed a technology for applying composite coatings based on iron on cylindrical surfaces, which makes it possible to vary the physical, mechanical and operational parameters of the formed iron-containing coating due to the planned selection of the deposition parameters. This eliminates the need for mechanical treatment of the applied coating, which is the reason for the high degree of rejection parts that undergo the iron-on operation. Contact interaction of the working tool with the formed layer of the composite coating has a positive effect on the value of its roughness.

Abstract: The article presents the features of vibration processing of parts of electronic equipment in granular media. The method of combined processing by mixing granules with cutting and activating properties is considered as one of the ways to increase the intensity of vibration treatment. The increase in intensity is experimentally confirmed on the basis of a multivariate experiment with the construction of a regression model of the process.

Abstract: Formation of roughness during treatment by polymer-abrasive brushes occurred as a result of interaction of cutting micro-relief with processed surface. The cutting micro-relief of abrasive instrument is described in the form of random process with normal distributional law. When calculation of roughness, the depths of penetration of cutting lugs in processed material as well as regularity of changing of radial radius of rounding of peaks of cutting lugs from modes of treatment are taken into consideration. Set are relations of roughness of processed edge from modes of treatment (deformations of instrument, cutting velocities, feeding) as well as from constituent cutting force. It is proved that usage of polymer-abrasive brushes for rounding of edges faces all requirements of aviation industry on roughness of processed edges.

Abstract: The article discusses the effect of the surface conditions on the corrosion resistance of alloys based on cobalt, titanium and stainless steel, which are currently used for the manufacture of components for implantable medical devices. It is shown that an increase in surface roughness has practically no effect on the corrosion resistance of alloys based on cobalt and titanium.

Abstract: The influence of the effect of combining different types of processing based on the physical force acting on the surface of conductive materials and the electrochemical active action of electrolytes acting as a cutting fluid is considered. The experiments carried out and show a significant effect of these types of processing on the surface quality and the provision of the initial various physical and mechanical properties of the processed materials. The article presents various dependencies of qualitative parameters for the implementation of shaping processes using such blade processing operations as turning, threading in holes of small diameter and expanding the holes. With combined processing methods, the process of forming the finish surface is due to the combined action of the cutting tool and the anodic dissolution of the metal under the influence of an electric current in the electrolyte solution. The application of this method allows obtain higher quality parameters when machining aluminum and copper alloys, the surface formed during processing, including the preservation of such special characteristics of certain materials, such as porosity.

Abstract: In the Caspian region, the Tengiz oil field has a high content of sulfur, salts and mechanical impurities, which contribute to the rapid deterioration of equipment. The use of titanium alloy allows reducing corrosion wear 2-3 times. Based on the analysis of the design of the slide gate valve, the most exposed parts were identified, which were replaced by Grade 5 titanium alloy. Bench tests of the slide gate valve were put into operation. Laboratory work was carried out to apply titanium-based coatings to steel samples. The result was a structure with a microhardness of 730-810 HV sufficient to protect it against corrosion wear.