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In conventional steels, bainitic microstructure which forms under isothermal conditions consists of bainitic ferrite and carbide precipitates whose distribution and size substantially depend on the pa-rameters of isothermal treatment. In CFB steels (Carbide Free Bainite) however, the main micro-structural constituents are bainitic ferrite, retained austenite and, sometimes, the M-A constituent. CFB microstructure may possess better ductility and the same or even higher strength than micro-structures of bainitic ferrite and carbide precipitates. This advantage results from the principle of formation of the CFB microstructure and is related to the absence of brittle carbides and their substi-tution with retained austenite. This paper explores the effect of austempering on mechanical proper-ties of unconventional CFB steels 42SiCr and 42SiMn.

Taking the discrete degree of bearing raceway grinding surface integrity as the research object, the orthogonal test based on the wheel speed, workpiece speed and grinding depth is designed. The residual stress, retained austenite, hardness, grinding modified layer thickness and roughness of the raceway after grinding test were measured, and the mean value and standard deviation of these indexes were calculated. The results show that the standard deviation of residual stress and roughness decreases with the increase of wheel speed, and the standard deviation of retained austenite, hardness and grinding modified layer thickness keeps stable. Finally, the optimal grinding parameters considering the scatter of surface integrity are selected.

In this paper, innovative resistance element welding (REW) technology for joining galvanized steel sheets to thermoplastics (PMMA) is introduced. The essence of the innovation is in the use of a special bimetallic joining element consisting of the core made of a Sn60Pb solder, and the sleeve made of a Cu tube. During resistance heating, the solder melts, thus allowing the formation of a metallurgical joint with galvanized steel sheet. Since Sn60Pb solder melting occurs at temperatures (from 183 to 190 °C) be-low the thermal decomposition temperature of most thermoplastics (for PMMA above 300 °C), there is no thermal destruction of the PMMA material around the joint. The mechanical fixation of the thermo-plastic material at the overlap joint is provided by the sleeve made of Cu tube which has a substantially higher strength than a Sn60Pb solder.

In the article, the study of polymer properties is dealt with as a result of production technology on pat-terns, which were made by injecting, machining of the extruded profile and 3D printing. All samples were made from iglidur® J260 material, and they were subsequently tested in order to find out properties of roughness, breaking strength, hardness according to Shore, friction coefficient and swelling. Further-more, the samples were exposed to light microscopy, where material structure was studied, especially from the view of structure defects, distribution and shape of solid lubricants. Based on the performed experiment, it can be stated that production technology affects some properties of the sliding bushing. Above all, properties of the sliding bushing were affected by 3D printing technol-ogy. The measured samples had the worst results with regard to roughness and swelling values. Con-versely, the values acquired by measuring hardness were surprising as the 3D priting samples reached better results than the samples made by machining. The samples created by injection had the best re-sults compared to others in all tests. The measured values corresponded to the values listed by the man-ufacturer. Machined sample of the extruded profile is mainly affected by the type of machining, but with consideration to the structure, it can be claimed that the extruded material has the same structure as an injected piece and its properties, with the exception of surface roughness, are on the same level.

The paper derives mathematical and ggraphical relationships between technological parameters and result of metalworking, in the application of progresive cutting materials based on coated cutting tools of sintered carbide and cutting ceramits. The development of new cutting and machined materials leads to new perspectives on their interaction in the machining process. This process leads to patterns between cutting conditions and machined results. These need to be defined and used in favor of efficient machining of mechanical components in practice.

The paper deals the production of porous aluminum materials that are characterized by lower density and mechanical properties. Samples of porous aluminium materials were produced on the basis of the developed methodology that applied sodium chloride particles of different sizes (average size 4, 6 and 9 mm). The AlSi12 foundry alloy was preffered for the production of the aluminium porous material. As part of the experiments, samples of porous aluminium material in the shape of a truncated cone were made. The cavity of the foundry mould was in the shape of a truncated cone with diameters: D = 0.047 m, d = 0.040 m and height v = 0.040 m. The material properties were determined on the produced samples. Their weight, volume and their density, relative density were calculated. Based on empirical relations, their value of Young's modulus of elasticity and value of thermal conductivity were determined. The compressive strength of selected samples was monitored as well. The value of Young's modulus of elasticity was determined from the measured stress-strain course. Furthemore, the porosity of the produced samples was evaluated on a scanning microscope.

Welding techniques such as gas tungsten arc welding (GTAW) can induce solidification cracking owing to the wide solidification temperature range. Riveting or mechanical fastening are plausible alternatives, but can create problems like material loss, overall weight increase, corrosion, and introduction of high stress concentration areas. This study proposes a new welding method to improve and minimize centerline solidification cracking in GTAW called “tandem side-by-side GTAW welds”. AA2024 is fusion welded using GTAW, and its solidification cracking behavior is investigated and compared for two weld pool motions (straight and weaving) and the proposed method. The fishbone test was used to assess centerline solidification cracking susceptibility. The results of welding AA2024 autogenously proved that the tandem weld pool motion is superior to the other two GTAW methods. As a result, the proposed method showed lower stress concentration areas by forming less concave weld shapes, lower heat input, formation of preferable grain size and orientation thus shorter centerline solidification crack lengths with a tortuous crack path motion obtained in comparison with the straight and weave.

One of the key components in making Industry 4.0 a reality includes machines that are able to produce required products and components faster, more precisely and more flexibly than ever before based on so-called reverse engineering technology. Reverse engineering is a technology that enables rapid acquisition of data for CAD, CAM, CAE, thereby greatly shortening the development, design and fabrication of parts. In general, analogue data is converted to digital data, which is further processed. The paper deals with the analysis of prototype models of disc milling cutters with different blade profiles. The inspection of the shape of the disc-type prototypes is based on the reading of the digitized reference CAD model (workpiece with machined grooves), the subsequent positioning of the digitized protrusions of the disc mill cutters (milling cutter with edge profile 1, a milling cutter with edge profile 8) with respect to this reference CAD model, creating a colour map of the deviations at the selected points. The aim of the paper was to analyse the resulting wear (deviation of the dimensions at selected points) on the prototype of the disc milling cutters with the profiles of blades 1 and 8, which was simplified on the workpiece with the machined profiles of the grooves 1 to 4.

The aim of this paper is an analysis of the dependability of critical components of the John Deer 7530 tractor. For this analysis data was used from a database which contains maintenance data of 166 trac-tors during approx 9 years. The first part of this article is devoted to the selection of critical compo-nents based on number of failures of individual machine parts for a given period and their sales pric-es. The next part of article presents data for calculation dependability indicators which contains oper-ating times to failure and operating times without failure. Due to the large size of the data files of the individual components, the data are only given for one machine component. Furthermore, the meth-od of calculation of dependability indicators is described by parametric statistical methods according to ČSN EN 61649:2009 and mean time to operating failure. The results of the analysis are summa-rized in tables and graphs. The method in this article can be used to optimise the maintenance pro-gram.

The main aim of this article is study the cause of gear wheel failure. This component has worked in the motorcycle gearbox. During the operation of the transmission, the gear wheel tooth was broken, which made it impossible to continue running this device. The investigation of the damaged area was focused on determining the chemical composition of the gear wheel material as well as detecting chemical changes in microlocalities close to the defective areas. The method of energy-dispersive spectroscopy was chosen for this type of analysis. Furthermore, the micropurity and microstructure of the material were evaluated by methods of optical microscopy and scanning electron microscopy. Using a thermo-emission scanning electron microscope, the fracture surface was evaluated in the mode of secondary electrons and also in the mode of backscattered electrons. In this way, the fracture surface was examined in terms of its micromorphology as well as material contrast.

The topic of the article is to compare the mechanical properties and define the differences in the degra-dation process for anticorrosive glass fibres type AR and for glass fibres type E after influence of the alkaline environment in the geopolymer composite. The ongoing reactions between glass fibres and al-kaline environment lead to the dissolution and slowly decomposition of the fibres and consequently to the loss of the mechanical properties of the composite. Corrosion of glass fibres is characterized by weight loss, change of fibre diameter, reduction of mechanical properties and formation of mineral in-crustations on the surface of the fibre, which gradually leads to the formation of a continuous corrosion coating so called corrosion shell. Scanning electron microscopy was used to monitor the morphology of the fiber surface, and image analysis methods were used to evaluate morphological changes. Tests of mechanical properties (fibers - tensile test, composite materials - three-point bending and Charpy test) were used to confirm ongoing degradation processes due to the long-term influence of the alkaline envi-ronment on both types of glass fibers.

Research on efficient machining of hardened surfaces is invariably of interest because the number of wear resistant surfaces on the machined parts is increasing. These surfaces can be machined by both single-point (cutting) and abrasive (grinding) tools. However, in designating the finishing of the parts, the working characteristics of the products that the parts are intended for limit the finishing options. In this paper the results of a comparative experiment are introduced. In the experiments the allowances were removed from the hardened surfaces of the parts by turning, grinding or a combina-tion of them. The comparative analyses were carried out for the roughness and accuracy of the ma-chined surfaces and the procedures were assessed.

The effect of the nitrocarburizing process in pastes with heating in a chamber furnace on the struc-ture and strength characteristics of 09Cr15Ni8Al corrosion-resistant steel was investigated. The tech-nology of chemical-thermal treatment was developed, which included nitrocarburizing in pastes with heating in a chamber furnace at different holding times. The thickness of the diffusion layer and its microhardness were determined after nitrocarburizing. To determine the efficiency and select the modes of chemical-thermal treatment, tests were carried out for the investigated steel's strength characteristics. The main feature of the structure of the diffusion layers of valve steels, obtained by nitrocarburizing in the nitrogen-carbon paste, is the presence of an inhomogeneous layer with clearly distinguished zones.

This article deals with the calculation of pressure vessels for beer maturation using analytical calcula-tion according to ČSN standards and with the help of commercial software PVESS. The article pre-sents commonly used procedures in the design of pressure vessels, resp. vessels for use in the brewing industry in the assembly of pressure vessels stacked on top of each other. The article describes the main parts of the brewery tanks, including the procedure for their design. The choice of materials used, the choice of basic dimensions of pressure vessels was determined in the work. The tank vessel is made of stainless steel 1.4301 or 1.4541. The advantages of this material in the brewing industry are also presented. From the given input parameters, a control calculation of the strength of pressure vessels was performed. The result of the work was the verification of the calculation, finding out the deviations of the measurements using mathematical software with a common calculation according to the valid standards for the calculation of pressure vessels.

Providing products with higher quality and lower prices is considered to be a competitive advantage for the industrial firms over competitors. This main challenge can be achieved by minimizing the overall production costs and operational time. Lean manufacturing provides many tools and techniques to iden-tify and eliminate wastes and to reduce costs in production systems. In this paper, single minute ex-change of die (SMED) technique is used as a lean manufacturing approach in a leading Palestinian aluminum profiles company. SMED was implemented through real experimental procedures applied to the extrusion line processes to investigate its effect on decreasing the setups time and improving the Overall Equipment Effectiveness (OEE) of the extrusion machine, in addition to introduce a guide for practitioners to improve the extrusion process dies exchange in similar industries. Overall, the successful implementation of SMED resulted in an increase of OEE by 3.26% as the consequence of the increase of machine availability by 4.86%.

Metal machining is a complex technological process based on material removel from semi-product by the influence of a cutting tool which is abrasion-resistant at high mechanic and heat strain. The essence of material removal is based on considerable material plastic deformation under the tool cutting wedge, the result of which is a deformed chip and transformed workpiece surface, which must comply with the geometrical and mechanical workpiece characteristics. These are determined by selected cutting conditions, geometrical and mechanical characteristics of the cutting tool. The selection of cutting conditions is engineering art and requires deep knowledge of machining process, mainly the relationship between cutting conditions and ther results of machining. These relationships are being tried to identified in the paper.

The paper describes the course, conditions and results of the impact test of the supporting frame of the test station for dynamic tests of gears. The test station makes it possible to simulate different gears operating conditions. The basic support frame structure of the test station was evalu-ated as unsufficient based on the results of measurement and processing of the measured low and high fre-quency vibration values in the verification series of experimental tests. The basic failure of the origi-nal design were the significant resonance actions that were the results of the dominant sources of vibration being near the natural frequencies of the vertical and horizontal beams of the test station base. A structural design of the test station supporting frame was designed and implemented. The goal was to increase the rigidity of the frame and eliminate unwanted resonance phenomena. The impact tests were used to determine the values of the natural frequencies of the most stressed parts of the supporting structure - vertical and horizontal beams, before and after implementation of struc-tural modifications. The comparability of the impact test results was determined by adherence to identical measurement conditions.

In this article, we studied the phenomenon of instability which is the buckling of the beam elaborated of steel (E36-S355), and magnetorheological elastomer subject to compression-flexion solicitation. The study of the influence of the intensity of the magnetic field on the buckling instability of compressed hybrid beams is done by a mathematical development using the Ritz approach and by a numerical simulation under the Abaqus calculation code. The obtained results show clearly that we can control the instabilities of the adaptive intelligent beams behavior by the magnetic field.

Aiming to improve the working life of high-speed rail bearings, this paper puts forward a comparative study on different types of high-speed rail bearings at extreme low temperature. The model of bearing life is established. In the whole test process, it is found that the change trends of bearing temperature, environment temperature and torque are basically the same. In the equilibrium temperature relationship between SKF and ZH bearings, the temperature divergence of SKF bearings finally appears. In the ZH bearings, bearing 4 appears irregular sharp drop at the end. However, the temperature changes of the two brands of bearings are between-150 ℃ and -170 ℃. And the friction coefficient is proportional to the ratio of torque. In the comparison of grinding amount, the wear amount of ZH bearings is far lower than that of SKF bearings, with a difference of about 0.5 mm. This shows that the production process and surface treatment methods of the two types bearing are completely different.

A new Coupler Critical Dimensions (CCD) approach to define mobility criteria (crank, rocker conditions, or existence) for linkage mechanisms has been presented in this paper. The idea is to analyze the extreme lengths of a mechanism coupler link when the mechanism is on the extreme of its existence or changing its mobility condition. The method leads a set of expressions of the constant mechanism parameters that can be used to define the exact dimensional limits of the coupler link in the mechanism. These expressions present sufficient and necessary dimensional conditions for the mechanism existence and become a turning point to change its mobility from crank to a rocker and vice versa. At the boundaries of the coupler dimensions, the mechanism reaches its the change-point configuration where the mechanism may switch either from one work function to another or from existence to non-existence. The method has been successfully applied to the planar 4R, spatial RSSR, and planar multiloop linkage mechanisms. The obtained results prove the effectiveness and accuracy of the method in defining the limits of the mechanism rotatability conditions or existence in general.

In this paper, the dependences of the tangential component of the velocity of movement of the medium granules, inside the oscillating reservoir, on its radius and oscillation period are obtained. For the anal-ysis, the circulatory motion of working medium granules under the influence of a rotating impeller and the dynamics of a pseudo-gas from abrasive granules exposed to rotating processed parts and an im-peller, are considered. From the results, the comparison of the energy impact on the working medium of the rotating processed parts and the impeller is carried out and the distribution of the pseudo-gas velocity from the abrasive granules and its pressure on the surface of the processed parts are obtained. Furthermore, the mechanism of pseudo-gas flow around a rotating part from granules of the working medium is presented. Finally, the schemes of the arrangement of the part in a cylindrical reservoir and its flow around the lateral surface of the rotating part are shown.

With the rapid development of science and technology, the means of industrial production have become more diversified and intelligent, and the development of new means of industrial production has become an increasingly important research topic. Therefore, the automatic assembly technology was studied taking machine vision system as the main research subject in this study. An automated assembly model of industrial technology based on machine vision recognition was established, parameters such as the part positioning parameter, assembly time, the number of parts wrongly assembled and the number of parts missing and the qualification rate of assembly were obtained, and the corresponding experimental conclusions were obtained. Moreover it was compared with the traditional manual assembly technology, and it was found that the automatic assembly technology based on machine vision recognition had better performance and more remarkable experimental results compared with the traditional manual assembly technology, and the traditional manual assembly technology needed continuous modification and optimization. This work provides a new route for automatic assembly technology in industrial technology.

Planning a process of production, among other machining processes, is an important stage in the production of products. The developed machining process should allow production of parts with the planned dimensional accuracy and specified surface roughness. With reference to the above, the scope of the carried out theoretical work included determining the dependences between parameters of the drilling process, tool wear, as well as the impact of these parameters on the hole quality. The main aim of experimental research was to analyse cutting tools wear in various phases of tool usage. The research consisted in observation of metallographic microsections to analyse changes occurring in the drill bit microstructure. Then the microhardness was measured and in the next step the micro-hardness of the tested drills was statistically compared. Based on the results obtained, the percentage of wear for drill bits depending on microhardness was estimated taking into account the earlier esti-mated Percentable Production Cycle (PPC). This allowed determining the degree of wear and tear of drills by comparing the microstructure and microhardness between them. The aspects of cutting tool management are also discussed.

The work presents the possibilities of using the thermomechanical analysis to design composite systems with carbon fibers, which should have a low coefficient of longitudinal thermal expansion will be potentially valuable in the form of calibrated length gauges. ChS Epoxy 520 epoxy resin (hardener T0492) was used as a matrix for composite production. Carbon fibers were tested in the form of short recycled fibers and continuous fibers in roving and fabric. The values of the coefficient of longitudinal thermal expansion of all prepared systems were determined below the glass transition temperature of the polymer matrix in the temperature range of 5º to 40ºC, i.e., in the range suitable for use in technical practice. From the obtained results, it is evident that carbon fibers significantly influence the epoxy matrix behavior. The coefficients of longitudinal thermal expansion of the epoxy resin in this temperature range from 47.6 to 65.2 [10-6 /K], the coefficients of the composite system with recycled carbon fibers with a random arrangement from 38.6 to 47.6 [10-6/K], coefficients of systems with a parallel array of fibers from to 3.4 to 2.7 [10-6/K] for carbon fibers in the form of roving and 4.3 to 2.0 [10-6/K] for carbon fibers in fabric form.

The current study investigates the influence of the dressing process of the vitrified bonded microcrystal alumina grinding wheel on the roughness of the machined surfaces in cylindrical grinding of Ti6Al4V alloy using different types of stationary diamond dressing tools. For the research, four types of dressers were selected, which differ from each other by number, size and location of diamond cutting elements. Each dresser has been tested at four different dressing feed values with the same dressing depth. Two sets of experiments were conducted to determine the tendency of grinded parts roughness parameters change depending on the dressing feed for each type of diamond dressing tool at two values of grinding feed. A comparative analysis was carried out to show the dressing feed influence and the effect of the diamond dresser type select on the roughness parameters of the grinded surfaces.

The work is focused effect of different temperature nozzle in additive manufacturing process FFF (Fused Fila-ment Fabrication) technology for the most common materials (PLA, PETG and ABS). A standard specimen internal structure arranged ±45° in longitudinal print direction with 100% infill. For the exact testing are used no perimetres. The specimens were printed by minimal, middle and maximum nozzle tem-perature. Temperature range is given by the filament company. To ensure relevant testing materials from the same company in one colour were used. A printed specimens were testing by destructive testing method on tensile testing machine. For testing were made five specimens in one setting. Finally, were made 45 specimens for tensile testing.

The laser welding method is one of the youngest but the most progressive welding methods. The advantages of laser welding include: simple automation combined with modern computer technolo-gy, very low heat input to the weld, high productivity, high welding accuracy and low noise during laser operation. In this work, the sample meltings were prepared in a protective atmosphere varying the welding parameters – laser power, welding speed, or focus position. A total of 12 samples were prepared this way. The aim was to evaluate the shape and depth of the melting of the material for selected values of parameters. Based on this metallographic evaluation, the optimal welding parame-ters were selected for a pair of austenitic stainless steel tubes (X2CrNi19-11 and X5CrNiMo17-12-2) for fiber laser welding. Macrostructure and microstructure evaluations, microhardness tests and tensile tests were performed on these welded samples.

Nitriding is a technology that leads to an increase in the utility value of the product. It’s most im-portant benefits include increased corrosion resistance, abrasion resistance, wear resistance, increased resistance to fatigue failure under cyclic loading, and many others. The design of a suitable nitriding technology not only on the basis of empirics requires a closer study of the relationship between the structure of the nitriding layer, its properties and the course of a particular degradation process. Be-cause the life of most components is related to abrasion on the surface, the occurrence of fatigue cracks and corrosion effects, it is crucial to influence the mechanical and other properties in this sur-face area. High functional requirements are placed on the functional surfaces of steels for weapons production, which lead to a long service life, reliability and dependability of the components of the weapon system and its safe use. The paper discuss the influence of selected nitriding technologies on the mechanical properties of steel 42CrMo4 and 34CrNiMo6, especially on the hard and microhard-ness of surface layers, change of its structure and next to change the surface texture and dimension of component. The steels were nitrided in plasma and gas. Nitriding in gas led to more significant struc-tural changes in the surface layer of both steels compared to plasma nitriding.

The article is devoted to a comprehensive analysis of the coating of a component from the Ford Fo-cus 1.0 l EcoBoost engine. It is one of a pair of materially identical aluminum gears connected by a drive pulley and a drive. Aluminum gear components are surface treated with a mixture of metal powders using PVD technology, where the goal of the coating is to increase the hardness, abrasion resistance and heat of the base material. The chemical composition of the basic material of the gea-red aluminum drive wheel of the FORD engine proves that it is a component made by thermofor-ming and corresponds to the alloy EN AW 6061 (AlMg1SiCu) according to the standard ČSN EN 573 1-3. The microstructure of the base material component exhibits fine intermetallic phases evenly dis-tributed throughout the cross-section of the base base material, without the occurrence of larger inc-lusions and/or porosity. The cross-sectional microstructure in the area of the coating demonstrates that the component has a continuous uniform surface layer of the coating formed without a defect and does not have a diffuse bond with the base material. The measurement of the coating thickness of the component shows a continuous surface layer formed by powder metallography, which ranges from 70.1 µm to 143.9 µm. The surface EDS of the surface proves that it consists of deposited tungsten carbides produced by powder metallography and the bonding material is cobalt. Area EDS analysis of the surface coating identified morphologically two distinct areas of dark and light, where tungsten carbides and cobalt are based, and only the tungsten carbide and cobalt carbide contents change. The oxygen and carbon content also changes in the dark and light areas.

This paper highlights the findings of multi-material application in 3D printed specimens. The work presents experimental results of multi-material, and multi-color-based 3D printed specimens by a multi-extrusion printer developed at the laboratory. It aimed to determine the bonding properties between the layers of various materials indicated with different colors. The samples were printed across multiple infill models and tested in the tensile and compression machine. The specimens were created with 10%, 25%, and 100% infill having single and dual colors material. Polylactic Acid (PLA), Acrylonitrile Butadiene Styrene (ABS), and Flex materials were used for printing various specimens with various colors. The layers were printed synchronously. The filaments were changed according to the predetermined algorithm. The experimental results showed that the mechanical properties of single, dual, and triple mate-rial specimens differed according to the reinforcement strategy. In addition, the mechanical property of the same material with different colors was identical.