Robert Čep

Robert ČepVŠB-Technical University of Ostrava · Department of Working and Assembly

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    Research
    Research Items (50)
    Uniform austenite remaining in the microstructure of the martensitic transformation is called the residual austenite. It is undesirable structure in components, due to its slow decay causes dimensional instability in these components and reducing the hardness. There is a change in volume and it generate internal stress which often appear as cracks. The residual austenite is highly undesirable component in the molded components, as well as the production of gears and bearing components. The article deals with quantification of residual austenite in steels by using the Average peak method by X-ray diffraction. This method applies four separate peaks to determine the amount of austenite.
    The article deals with a comparison of machining of two chemically very similar materials of aluminium alloy, however, with various internal structures by means of non-conventional machining technology of electro-erosive wire cutting (WEDM). The first material used was a right parallelepiped of ALPORAS aluminium foam with porous structure produced by a method of powder metallurgy. As the second material designed to the comparison EN AW 5005 alloy was chosen owing to high aluminium content and therefore a very near chemical composition of the compared material. The samples with circular section of identical height and nominal diameter were produced. On the tested materials sizes of the cutting width were tested, surface structures after machining were observed, dimensional accuracy of cut samples were evaluated and time relationship between cutting of compact and porous structures of aluminium alloy were defined by means of a microscope.
    This paper deals with detection of surface damage after grinding through non-destructive micro magnetic technique based on Barkhausen noise. Paper compares the high and low frequency techniques and their sensitivity to detect surface burn and thickness of heat affected zone. The results of investigation indicate that the low frequency technique can more clearly detect surface burn than the high frequency technique due to relatively high thickness of heat affected zones obtained after grinding operations. The paper also discusses additional aspects of micro magnetic testing as a multi parametric technique where such parameters as Peak Position of Barkhausen noise loop correlate with the thermal load of machined surface. The paper also reports about corresponding structure transformations and associated stress state beneath the surface.
    This paper deals with the process of cutting of nickel superalloy and selection of suitable cutting parameters for its easy and effective cutting. The experimental part proposes three exchangeable inserts and determines the effect of feed rate cutting parameter during machining on durability and wear of the cutting tool. Depending on selected cutting feed rate and the amount of wear of these exchangeable cutting inserts, the quality of turned surface is evaluated and height roughness parameters are determined. In closing we show our observations obtained while machining Inconel 625, determine the effect of feed rate on durability and wear of cutting inserts, evaluate and recommend practical steps, describe the mechanisms of cutting wedge wear, determine the durability of the tool and roughness of the turned surface.
    This article deals with the test of removable ceramic cutting inserts during machining with an irregular interrupted cut. Tests were performed on a lathe, with a preparation which simulated an interrupted cut for us. By changing the number of slats mounted in the preparation, it simulated a regular or irregular interrupted cut for us. When it had four slats, it was a regular interrupted cut, whereas the remaining three variants were already irregular cuts. This paper examined whether it would have an irregular interrupted cutting effect on the insert and possibly how it would change the life of the inserts during an irregular interrupted cut (a variable delay between shocks).
    The article deals with the tracking of the wear development of cutting tools made from sintered carbide during parting-off of steel C45 (ČSN 12 050.1). For experiment were selected inserts from two producers of cutting tools with different geometry. The parting-off was realized in the workpiece axis and the whole experiment was divided into two parts, parting-off to zero and parting-off to pre-drilled hole into material. The experiment was evaluated on the principle direct microscopic method and was observed the wear on the flank of cutting tool VBB. Tests were realized in cooperation with Pramet Tools Šumperk, Czech Republic.
    One of main issues when evaluating or analysing quality and functional properties of work-piece is identification of status of residual stress. Every treatment or machining process generates residual stress in the surface and subsurface layers of the material structure. The residual stress has a large influence on the functional properties of the components. The article is focused on the method of triaxial measurement of residual stress after machining the surface of sample by high feed milling technology. Significance of triaxial measuring is the capability of measuring in different angles so it is possible to acquire stress tensor containing normal and shear stress components acting in the spot of measuring, using a Cartesian coordinate system.
    Uniform austenite remaining in the microstructure of the martensitic transformation is called the residual austenite. It is undesirable structure in components, due to its slow decay causes dimensional instability in these components and reducing the hardness. There is a change in volume and it generate internal stress which often appear as cracks. The residual austenite is highly undesirable component in the molded parts, as well as the production of gears and bearing components. The article deals with quantification of residual austenite in steels by using the Average peak method by X-ray diffraction. This method applies four separate peaks to determine the amount of austenite.
    The article deals with evaluating of the resulting surface state of the three plastic materials and identification of suitable conditions for laser cutting with CO2 tube. As representative were chosen polypropylene, polymethylmethacrylate and polyamide. When cutting these types of materials it could melt eventually their re-sintering. A suitable combination of parameters is possible to achieve of sufficient quality of the cut. The samples were cut at different feed speed and laser power. Then they was compared on the basis of the measured roughness parameters Ra a Rz by using a portable touch roughness Hommel-Etamic W5 and dates was processed according to ČSN EN ISO 4287. Cutting of samples was realized at the Department of Machining, Assembly and Engineering Metrology, VŠB-TUO.
    Development and application of new materials in mechanical engineering practice create a lot of questions concerning their technological application. This paper focuses on research problems related to the PVD coated cemented carbide. The theoretical part of the paper informs about principle of PVD coating technology and describes the arc evaporation method used for coating in greater detail. It also deals with coating materials and types, their properties, possible applications and finally principles of the experimental methods used for coatings testing are explained. In the experimental part of the paper, the measuring and testing procedures are described and the test results are listed. Adhesion and layer durability were compared by cutting inserts with different PVD-nanostructure and nanolayer coatings. The tests were carried out by milling of carbon engineering steel 1.1191 (C45), because this steel is widely used in many industrial applications and it is used as reference material too. In conclusion the testing results are evaluated on the basis of obtained information.
    This contribution deals with experimental cutting of samples made of special Alporas aluminum foam. This foam has been made by a powder metallurgy method and the foam resulting structure features very diverse material porosity. Test cuts through the aluminum foil were done using an non-conventional WEDM wire electro-erosive cutting technology. Monitoring and analysis of effects of proposed processing parameters on the resulting cut quality was done as a follow-up. Achieved accurracy of individual samples and its repeatability was also evaluated. At the end of the contribution wire cutting of aluminum foam technology findings are summarized and possible recommendations for practice are presented.
    In this paper the results of investigations carried out in the field of hole-flanging in thick steel sheets were presented. All experiments were performed in the Division of Metal Working of the Institute of Materials Technology at the Poznan University of Technology. Experiments of hole-flanging were carried out using cylindrical, spherical and conical punches. The blanks made of BW11, 34GHA and 15HGMV steels were investigated using different holes diameters. The holes were prepared using boring and laser techniques. The influence of the method of holes preparation on the quality and dimensions of obtained flanges were discussed.
    The paper deals with a new concept for the detection and prediction of the catastrophic tool failure (CTF) of ceramic inserts using an acoustic emission (AE) technique and an associated analysis of the chip formation during hard turning of bearing steel 100Cr6. The suggested method is based on the application of two sensors and the ratios of parameters of the acoustic emission such as AE RMS, AE absolute energy, and AE strength. The specific character of the segmented chips during hard turning is associated with the raw acoustic signals as well as the extracted AE features. The paper indicates that the conventional data processing of acoustic emission signals enables the detection of CTF. Tool wear connected with the cutting edge micro-chipping is related to the slow increase of tool wear (mainly flank wear VB) and stable values of AE features in the normal phase of tool wear. The CTF alters the AE waveforms as well as the course of the AE features. Conventional AE signal processing enables the detection of tool breakage. However, approaching CTF itself cannot be reliably predicted. Hence, a new concept of AE processing based on the ratios of the extracted AE features obtained in the different frequency ranges is suggested.
    This paper is focused on the comparison of the characteristics of materials cutting of different structures for testing intermittent cutting. Materials comparisons in the machining of steel strips samples C45 (12 050) are: cutting ceramics and cemented carbides. These materials have different characteristics of the cutting properties. Intensive development in the form of improved cutting properties passed in recent year's just cutting ceramics. This is what resulted in its use not only for machining a continuous section, but its application was extended to the intermittent cutting machining.
    The article deals with problems of cutting process monitoring in real time. It is focused on tool wear by means of impedance layers applied on ceramic cutting inserts. In the experimental part the cutting process is monitored using electrical resistance measurement. The results are compared and verified using the monitored cutting temperature and tool wear. The testing of impedance layers is reasonable mainly for cutting edge diagnostics. The width of this layer determines the wear allowance of tool wear (flank wear). Excessive wear causes a sharp reduction of this layer and thus a sharp increase in electrical resistance, which is a warning signal of the end of the cutting edge durability.
    This article is interested about drilling the holes to the alloy wheels. Tested were drills to drilling holes for screws and service holes. For screw holes was tested the three-stage drill with inserts from polycrystalline diamond. Drilled are two different diameters and the transition spherical or conical surface. The service holes were drilled with cemented carbide drill availible from Mapal labeled Mega-drill-Alu-180. During test, was modified the geometry of the drill and we watched what will be the effect of applied modification. Tested was seven variants of regrinding the drill. We evaluate the surface roughness, but also if the drill has the right position and not be pushed away from its axis. Finally was tested drill with three edges. This drill bit is from company Mapal labeled Tritan.
    The paper is focused on the issue of cutting tools for group of materials M, according to ISO 513, more exactly the area of stainless steel machining. The aim is to analyse and compare the current range of milling tools, namely Pramet Tools and competition (Mitsubishi, Sandvik and Seco). The main objective is to make a practical comparison of selected milling cutters and their inserts. In terms of experimental machining tests an aimed experiment on tool life comparison will be conducted under real cutting conditions in Pramet Tools testing laboratory. Tests are performed on the milling centre - Kovosvit MAS MCV 1270 Power and stainless steel X2CrNiMo17-12-2 was selected as machined material. In conclusion photographs are shown of tool wear on tool faces and flanks, tool wear progress for both groups and final results.
    The paper deals with an analysis of deformation processes and the aspects related to a chip formation such as the chip thickness, the chip ratio, the shear angle and the chip segmentation during turning the hardened steel 100Cr6. This paper investigates the influence of the cutting speed through a metallographic analysis, a calculation of significant aspects of deformation processes and the resulting experimental study. This experimental study is based on an application of acoustic emission. The results of this study indicate that the cutting speed significantly affects the parameters such as the chip ratio, deformation angle or the speeds in the cutting zone. On the other hand, the experimental study allows an analysis of the specific characters of deformation processes and their real intensity.
    The contribution deals with comparing non-traditional cutting technologies from the point of view of generated surface roughness. The comparison is carried out for technologies of abrasive waterjet cutting, oxygen cutting, laser and plasma cutting. As an experimental material, EN S355J0 structural steel and titanium CP-Ti Grade 2 was used. Surface topography measurement was done using a Mitutoyo Surftest SJ-401 instrument, and an optical profilometer MicroProf FRT was used for comparison and verification of acquired surface data. The aim of the contribution is to clarify, on the basis of experimental measurements, the behaviour of a topographic function after various ways of cutting; the knowledge of the function is necessary for solving both theoretical and practical technological tasks. The topographic function, which is a basis for the prediction of quality and control of the cutting processes, was derived in an original way. The use of individual technologies depends on technical and economical possibilities and on environmental influences. The results of measurement of cut surface roughness are in good accordance with the results of theoretical analysis.
    The aim of the work is find out influence of feed rate on the quality for the machined surface, especially surface roughness. The experiment was carried out by cutting tool HURCO VMXt30 with respect to the following cutting parameter: cutting speed 250; 350; 450; 550 and 850 m.min-1, feed 0,1; 0,5 and 1,0 mm/tooth. For testing was used two most common materials in the steel grade 1.1191 (12 050) and 1.2343 (19 552), and we chose two ordinary parameters of surface roughness; Ra - arithmetical mean roughness deviation and Rz - the largest inequalities height profile in the transverse direction and the longitudinal direction of machining. The structural equations will be the result which can describe the character depending on the cut surface parameters.
    Due to the expansion of milling process with ball end mill in various branches of industry it became necessary for this process to be optimized. For this purpose it is necessary to identify the parameters that influence the process and establish their value for witch the results obtained to be the maximum in terms of qualitative and quantitative. Roughness of the surface machined can be considered as an important element that reflects the degree of successful optimization of this process. In order to solve the problems relating to the analysis and estimation of the surface roughness variation in ball end milling of C45 material with tool tilt angle, in this paper it was designed an experimental methodology followed by analysis of experimental data and estimation of surface roughness variation. The experimental research methodology presented in this paper can be extrapolated and used in a large number of processes.
    The article is focused on surface integrity at reaming with high-productive reaming MT3 head made by HAM-FINAL Company. The term surface integrity is the surface condition of a workpiece after being modified by a manufacturing process. A machining process produces a surface characterized by the shape, metallurgy and mechanical properties. These surface aspects clearly indicate that a machined surface is very complex. Obviously, a high-energy input increases the likelihood of metallurgical damage and therefore results in a poor surface integrity which has effect on final product. Taking into account different types of created energy transferred to the tested surface and subsurface layer, the basic factors influencing surface integrity are temperatures, residual stresses, metallurgical transformations and also surface plastic deformation. The aim of experimental part is surface integrity tested on holes by reaming MT3 head during manufacturing process and last aim is find out MT3 head tool-life with their evaluation.
    The article is focused on the experimental determination of tool-life for ceramic tool. Nowadays, machining with indexable ceramic cutting inserts can reduce manufacturing cost, if the cutting tool and the machine tool are designed to compliment each other. With the development of modern ceramic tool materials, they are more and more widely used in the field of metal cutting since their mechanical properties and cutting performances have been greatly improved in last decades. On the basis of previous tests the tool-wear was measured at constant cutting parameter which is more typical for High Volume Manufacturing Processes. The tested material, cast iron 25P, is used at car’s engine. The main aim of this article was to find out the performance for this material by arithmetic tolerance of Ra profile, the greatest height of Rz profile and the external diameter D and its connection.
    The article deals with the improvement of cutting-tool durability by using CAD/CAM systems. It proposes new roughing turning cycles where a variable depth of cut is applied. The experimental part verifies theoretical prerequisites when a flange is being machined with a sintered-carbide cutting tool. It compares the turning where the standard roughing cycle isused and the turning where the proposed roughing cycle with a variable depth of cut is applied.
    The article deals with experimental testing of the cutting ability of exchangeable cutting inserts. Eleven types of exchangeable cutting inserts from five different manufacturers were tested. The tested cutting inserts were of the same shape and were different especially in material and coating types. The main aim was both to select a suitable test for determination of the cutting ability of exchangeable cutting inserts and to design such testing procedure that could make it possible to compare and evaluate the cutting ability of the selected cutting inserts. After the testing the necessary calculations were performed for comparison of the cutting abilities and recording the tool-wear using a microscope. The cutting ability was compared and discussed.
    The article deals with experimental testing of the cutting ability of exchangeable cutting inserts. Eleven types of exchangeable cutting inserts from five different manufacturers were tested. The tested cutting inserts were of the same shape and were different especially in material and coating types. The main aim was both to select a suitable test for determination of the cutting ability of exchangeable cutting inserts and to design such testing procedure that could make it possible to compare and evaluate the cutting ability of the selected cutting inserts. After the testing the necessary calculations were performed for comparison of the cutting abilities and recording the tool-wear using a microscope. The cutting ability was compared and discussed.
    The tool wear has a significant impact on the cutting process and therefore tool wear monitoring is especially important for building intelligent machine tools which are capable of assessing their own states and reacting to important changes. This approach is based on the assumption that there exists a relationship between the spectrum of high-frequency vibrations measured on tool holder, in immediate vicinity of the cutting zone, and the tool wear degree. The wear causes changes in tool tip geometry, which has significant influence on the process of chip forming. At the same time, the erratic nature of chip forming process excites the cutting zone, generating a very broad spectrum of vibrations. Due to high input energy, these vibrations are very intensive, and spread through the entire machining system. In the paper, experimental results are shown which pertain to the relationship between the power spectral density (PSD) within 5 kHz to 50 kHz interval.
    The paper deals with an analysis of surface integrity in laser beam cutting process. Surface roughness and other well measurable geometric features of the surface generated by a laser beam are used to define the quality of machined parts and its surface integrity. A whole complex of properties of materials, whether physical, mechanical or technological and utility properties are in a close relation with the mechanism of material disintegration. As the laser beam is focused onto a workpiece, the heat generated in the material results in the development of surface deformation. This is connected with a consequent hardening of the material and results in a change in physical and mechanical properties. The resulting surface roughness is an indicator of unwanted alteration, or it presents a degree of maintaining the original structure of the material. Using a model for machining-induced surface integrity modifications, it is possible to identify a stress - deformation state of the material, to assess the quality of material and its functional lifetime. This objective can be achieved primarily through a systematic derivation and definition of functionally determined relations between the final state of the surface layer of the workpiece and process parameters, which is being considered as an integrated physico-mechanical whole.
    This paper deals with the influence of feed rate on the quality of the machined surface, especially surface roughness. The experiment was carried at cutting tool HURCO VMX t30 with respect to the following cutting parameters: cutting speeds 250; 350; 450; 550 and 850 m.min-1, feed 0.1; 0.5 and 1.0 mm/tooth. Machining was performed by five-tooth cutter FF FW D50-22-05 and cutting inserts FF WOMT 060212 TM IC908 on the steel grade 1.2343 (19 552) and 1.1191 (12 050). The evaluated parameters were values Ra - Arithmetical mean roughness deviation and Rz - The largest inequalities height profile [1, 2] in the transverse direction and the longitudinal direction of machining. As a result will be the structural equations which can describe the character depending on the cut surface roughness parameters.
    This paper compares three of the most common processes: laser, plasma and oxygen cutting in terms of economical point of view. It illustrates the introduction of thermal cutting methods into the manufacturing of the companies with an emphasis on their productivity. This comparison can be carried out only to a limited extent what is given by many factors.
    The article deals with difficult-to-machine cobalt super alloys. The main aim is to test the basic properties of cobalt super alloys and propose suitable cutting materials and machining parameters under the designation 188 when machining. Although the development of technology in chipless machining such as moulding, precision casting and other manufacturing methods continues to advance, machining is still the leading choice for piece production, typical for energy and chemical engineering. Nowadays, super alloys are commonly used in turbine engines in regions that are subject to high temperatures, which require high strength, high temperature resistance, phase stability, as well as corrosion or oxidation resistance.
    Heat distribution in machining is one of the phenomenological characteristics of this process because it significantly influences functional properties of machined surfaces. This paper deals with heat distribution during grinding of Ni alloy and its relationship to the quality of ground parts in terms of residual stresses. The analysis of the heat distribution is based on measurement of the temperature in the contact of the grinding wheel and the workpiece, and the tangential component of cutting force. The heat distribution when Ni alloy grinding differs from the heat distribution when grinding a conventional Fe alloy such as roll bearing steel mainly because of the low heat conductivity of Ni alloys. Also, the application of CBN and diamond grinding wheels significantly reduce the thermal exposition of the ground parts, primarily when applying cutting fluid. This fact significantly influences the residual stresses after grinding. The results of the analysis show that there is correlation between energy partitioning and residual stresses.
    This paper presents experimental testing of the cutting ability for indexable cutting inserts. The main goal will be to select a suitable test for determine the cutting abilities of cutting inserts. Nowadays all manufacturers want to achieve lower cutting forces so can permit higher speeds and feeds, without increasing the risk of chipping. For evaluating we had to design such testing procedure that it would be possible to compare and evaluate the cutting ability of the selected cutting inserts used for tests. In today’s competitive global market, quality and precision is the most important parameter. Tight tolerances and urgent deadlines are normal. In the machine tool business, companies must keep their cutting edge, or your company will lose its competitive edge.
    Production of nanomaterials by formation of extreme plastic deformation ECAP (Equal-Channel Angular Pressing) is a way of preparing nano-structures of engineering materials. A development of a nanostructure in steel AISI 309 (EN X15CrNiSi20.20) with the technology of ECAP, and a new method for determination of the grain size are analysed here. In this study, we also make a comparison, analysis and prediction of the grain size with other technologies. Samples of steel of AISI 309 type were deformed by ECAP method using up to 35 passes.
    In the field of laser cutting, the research area is oriented mainly to understanding of the mechanism of removal, as well as to the combination of factors entering the process. This process of disintegration of materials presents a problem of analytical approximation, elaboration, and description [1 - 5]. Compared with previous approach to a solution, we have chosen our own way and we focus on mechanical respectively stress-strain parameters of the material being cut and the mechanical balance system: material properties - tool properties - deformation properties. We shall present here the basic forms of prediction equations for calculating the roughness of cutting walls, as well as other equations which were derived by modifying the basic equations for different application purposes, especially to calculate the optimum traverse speed v(popt), optimal laser performance W-lasopt and technologically important ratio INDvpwopt = v(popt)/V-lasopt. These contain easily available input variables for substitution. The basic forms, including the modified forms are aimed at predicting the quality of cut with its depth limits. The paper presents the method of optimization of the ratio between the traverse speed v(p) and laser power W-las which minimizes the final surface roughness after cutting with a direct impact on corrosion resistance of materials.
    The paper deals with testing of ceramic cutting tools with an interrupted machining. Tests have been performed on fixture - interrupted cut simulator constructed at Department of Machining and Assembly, FME, VŠB-TU Ostrava within the scope of the Czech Science Foundation project. The criterion of tool wear is either destruction of cutting tool or 6000 shocks. Testing cutting tool material used in this research is ceramic cutting tool produced by Tungaloy Company. Tested machined materials are 13MoCrV6 and C45 steels. The cutting speeds (408 and 580 m/min) and cutting feeds (0.15; 0.2; 0.25 and 0.3 mm) are investigated with variable parameters whereas the cutting depth is a constant parameter. The pictures of index-able inserts and graphs of dependence at variable cutting speed and cutting feed are shown as a result of a conducted investigation.
    This paper deals with the control parameters for selected geometric accuracy measurements for a machine tool. The parameters were needed after a refurbished milling machine was purchased. After setting up the machine, it was necessary to check the geometric accuracy that can be used for precise milling. The whole check was performed in accordance with ISO 10791. Only selected parameters of geometric accuracy were inspected, and they were later compared with the prescribed values. On the basis of a comparison of these values we were able to determine whether the machine tool can be used for accurate machining.
    This paper deals with the influence of heat treatment on the deformation of parts and the following machining process. The regime of heat treatment significantly affects such aspects of material as structure, hardness and induced stress. Different process of heat treatment results in different deformation of parts and changes considering their dimensions. All these aspects are connected with the consecutive cutting operations such as grinding or hard turning, their stability, precision of produced parts, etc. Deformation of parts is also connected with the structure of material before heat treatment, placement in the furnace, regime of heat treatment and stress distribution around the parts. The results of the experimental study presented in this paper illustrate the connection between different heat treatment regimes and the following processing of parts.
    Many clients and plasma arc thermal cutting devices providers deal with the question which technological factor in adjustment process of cutting has the greatest influence on the final product quality. Many researchers and teachers deal with this issue during lecturing these knowledges for university students. The article presents the design and evaluation of plasma arc cutting technological process. Influence of technological factors on roughness parameters Ra of the steel surface ISO Fe510 have been evaluated using planned experiments. Using factor experiment, the significance of the four process factors: plasma burner feed speed, plasma gas pressure, nozzle diameter, distance between nozzle mouth and material have been observed. Regression models obtained by multiple linear regression indicates the quality level as observed factors function.
    This contribution deals with the research and proposal to change a position of tool axis against milled surface during multi-axial milling. Our tat-get is achieving an increase in milling efficiency (improvement of functional surface properties, increase in milling accuracy, increase in tool durability, decrease in energy load on a machine, and shortening of milling time). This research attempts to make production of shape planes more efficient. This concerns production of molds, impression dies, and other complicated parts in various engineering industries, primarily automotive and aircraft ones.
    This article is focused on the experimental determination of tool life tests for indexable ceramic cutting inserts. The set criterion of tool wear was VBBmax = 0,6 mm (in accordance with ISO 3685) or 30 pieces of machined sleeves. After at least one of the mentioned parameters was achieved, the tests were stopped and evaluated. Two types of cutting material by Saint Gobain Advanced Ceramics s.r.o. Company-ZTA 7 NI and D 250 were tested. We monitored their tool life at the same cutting parameters. The experiments were performed on machine tool - CHEMNITZ NILES N22. The machined material was the cast iron 25P mainly used for car engines. Tool wear was monitored on every fifth machined sleeve. Microgeometry was measured after tool wear test on each fifth sleeve. The aim was to determine the arithmetic tolerance of Ra profile, the greatest height of Rz profile and the external diameter D. The measurement was carried out four times; arithmetic average was performed subsequently as it is shown in the tables.
    The paper focuses on experimental research and evaluation of the abrasive waterjet cutting technology process in order to evaluate the technology factors affecting the microgeometry (average roughness) of workpiece surface of titanium of 10 mm thickness using a full factorial design. The significance of four selected process factors - independent variables (traverse speed, abrasive mass flow rate, angle of attack, depth of cut) affecting the surface quality was evaluated by a two level full factorial design. The surface quality was evaluated by Ra, Rq and Rz surface roughness parameters. A multiple nonlinear regression equation obtained from ANOVA gives the level quality Ra as a function of the machining factors. A different significance of these factors has been found.
    The paper deals with analysis of chip formation and related aspects of chip formation, like chip thickness, chip ratio, shear angle and chip segmentation during turning of hardened steel 100Cr6, The paper makes a comparison of sonic aspects of chip formation between turning annealed and hardened roll bearing steel 100Cr6. The results of the analysis show that there is formation of a segmented chip in the case of hard turning. This process of the chip formation significantly affects all parameters related to the plastic deformation in the Cutting Zone. Moreover, the formation of the segmented chip causes instability of a cutting process, the high intensity of tool wear and generation of significant heat in the cutting zone. The heat Causes high temperature in the cutting zone (thermal load of a cutting tool).
    1. vyd. Autoreferát doktorské disertační práce, Obor Strojírenská technologie--Vysoká škola báňská-Technická univerzita Ostrava, Fakulta strojní, 2005 Nad názvem: Vysoká škola báňská - Technická univerzita Ostrava, Fakulta strojní 35 výt.
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