This article deals with possibilities of an application of controlled diffusion processes in remelting of steel surface layers with an electric arc of non-consumable electrode, in the environment enriched by boron, with the aim to achieve an improved wear resistance. In the design of experiment, there was formulated an assumption that the dissociation and ionisation of environment can be achieved, allowing the initiation of diffusion processes in the surface layer of the steel remelted. Conditions for creation of hard and stable structures with required properties should be obtained by enrichment of surface layers. The steel grades 16MnCr5 and X8CrNiTi1810 were used in experiments. Values of hardness and relative abrasive wear resistance were measured on samples after remelting. The metallographic analysis of remelted samples was performed as well. A significant increase in values of studied parameters was observed when remelting in the boron containing environment. The dependence applies to the effect of the environment on the change of properties and boron content in the remelting environment.
Hard turning is a turning operation performed on hard materials (hardness more than 45 HRC) in order to reach surface roughness close to that obtained in grinding. The development of this technology was accompanied by the development of new cutting materials such as cutting ceramics, cubic boron nitride and polycrystalline diamond. Especially cubic boron nitride has found its use in hard part turning operations because of its characteristics. However, new cutting materials result in new questions, which researchers are trying to solve. The major consideration for a user of this relatively new technology is the quality of parts produced and how the new cutting material will behave during machining. This paper aims to document and describe the process of wear on the cutting edge of a tool made from cubic boron nitride of a different grade and with a different geometry of the cutting edge, and its influence on surface roughness and quality. Wear was documented by a digital microscope with measurement option. Surface roughness was measured by a roughness meter. A notable observation from this research is that the flank wear of the cutting tool has a large impact on the quality of machined parts (especially surface finish and surface integrity) [1].
The production process is a role of the management system consisting in determining the optimum, most economical or productive conditions for implementing a particular manufacturing operation. The management system of production process should ensure that the given process complies with its intended use without undesirable failures or risks Vysočanská et al., 2009).The machining of materials is a working process by which a semi-finished product obtains the required shape and dimensions of a part by removing the material from the surface layer. The most widespread method of machining is cutting in which material is removed in the form of chips by mutual interaction of the tool and workpiece. Based on a long-term development of cutting materials, creating a completely new cutting material cannot be expected in the near future; therefore, the research of leading manufacturers of tools and cutting materials is primarily aimed at improving existing materials, specifying their optimal use, and exactly defining fields of their application.In the cutting process, the cutting part of the tool is exposed to high temperatures, mechanical stress, friction, vibrations and sudden thermal and mechanical shocks. Therefore, the measurement and examination of material behaviour under these conditions is an integral part of the research and development of cutting materials.The aim is to monitor and evaluate changes in cutting forces between the cutting tool and workpiece in turning, induced by different properties of individual cutting tips, and also monitoring changes in these characteristics in three different speeds of the lathe spindle.We have focused on studying the effect of cutting material (exchangeable cutting tip) and chip former geometry on cutting forces. In order to monitor the effect of one factor only, measurement conditions were necessary to be ensured so as to eliminate other factors that could influence the change in these parameters. We used the cutting tips of the same type (DNMG 150608), of various cutting materials, and with several chip former types. When assessing the effect of cutting material, we compared only those tips the only distinguishing feature of which was cutting material. We proceeded in the same way when assessing the effect of the geometry of cutting tips chip former. Furthermore, we were also interested in how individual cutting tips behave at different speeds; therefore, our measurements were conducted at three different speeds, i.e. n 1 = 710 rpm -1 , n 2 = 1,400 rpm -1 and n 3 = 2,240 rpm -1. Other cutting conditions were held constant, i.e. cut depth a p = 1 mm and feed rate f = 0.1 mm -1 . Steel 11 523 belonging to the group P was used as a material sample. The cutting tips used for our measurements are intended for machining this group of materials. Characteristics of sampleFour samples of the same shape, size and material were used for the experiment.The dimensions of the sample are shown in Figure 1. The sample was clamped using a three-jaw chuck. Since we needed to avoid vibration, ...
This contribution focuses on hole drilling into grey cast iron and steel 11 523. The most used method of hole machining is the one using a screw drill HSS to reach the accuracy class from IT 11 up to IT 14. Surface roughness ranging between Ra 3.2 μm and Ra 6.3 μm depends on the parameters of the drill used and drilled material. An emphasis is put on the accuracy of shape and dimension as well as on meeting the tolerance limits of holes [1,2,3,4,5]. In most cases, it is possible to reach those conditions using the common methods of hole drilling. Finishing such as roughing, reaming and countersinking is used for meeting high-quality requirements [6,7,8,9].
This paper focuses on demonstrating the eff ect of cutting materials and the geometry of cutting blades on roughness during the turning of machined surface. Experiments have been targeted at measuring roughness when turning a sample of 11 523 steel at constant parameters of shi and depth of cut and under variable values of spindle speed. Measurements were performed by using replaceable cutting blades of diff erent types and parameters. Results were evaluated in terms of the eff ect of diff erent properties of cutting blades and variable values of spindle speed.
This paper is focused on an emphasis of the preventive maintenance effect on reliable and safe operation of technological equipment, in view of technical diagnostics. Problems of the boroscopy as a diagnostics method providing fast information acquiring of inner parts of technological equipment turbomachinery RB211 DLE assembled in combined cycle gas turbine (CCGT) in selected company [. Observations were focused on high pressure axial compressor, being the main part of monitored technological system. From quality point of view the paper provides new perspective of internal inspection of technological equipment covering possible damages locating and qualifying of qualitative characteristics of equipment inner parts. The problems solved were based on particular practice demands and it reflects state-of-art in concerned scientific field [.
This paper describes the experiment of measuring the temperature and cutting force during the drilling of short holes without using cutting lubricants, at constant cutting speed, and at increasing shi . Measurement was performed on steel samples of grade 11 523. During drilling, temperature was monitored by a thermocouple, using the method of two foreign metals. Cutting force was measured by a strain-gauge sensor. The experiment provides a quick orientation in the given issue and points out to the optimisation of cutting conditions. Based on results, it can be stated that the range of temperatures and the size of cutting forces depends on technological conditions, cutting parameters, and mechanical and physical properties of tool and workpiece's material.
This paper deals with the possibility of applying controlled diffusion processes in the remelting of steel surface layers using the electric arc of non-consumable electrode in the environment enriched with selected elements. The objective was to achieve an increased wear resistance. Boron was used in experiments as an alloying element. An assumption was stated in the experiment design that environment dissociation and ionisation can be achieved using electric arc, allowing diffusion processes initiation in the surface layer of remelted steel. Conditions for hard and stable structures formation with required properties should be achieved by surface layers enriching. Steel grade STN 41 5230 was used in experiments. Hardness and relative abrasive wear resistance values were measured on samples after remelting, being crucial as for required properties of surface layers. Not only hardness values were measured in the remelted layer but also their course inwards the material up to reaching the depth of base material not affected by heat. The metallographic analysis of remelted samples was made as well. A significant increase of parameters observed in the boron remelting environment was found. The dependency of the environment effect on the change of properties and boron content in the remelting environment was observed.
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