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The production of precise castings by investment casting becomes an increasingly important manufacturing technology and many of isues of this method have to be addressed. This paper deals with evaluation of critical points on wax patterns of small blades. After the casting of certain product, the casting had a deviation from the required dimension. Investigation revealed that the effect on the resulting dimensional deviation is not only the casting process but also the wax pattern injection process itself. The engine and turbine blades are one of the most important parts in turbine or aircraft engine machinery. Casting deformation is an important feature of evaluation the quality of the turbine blade. In order to control the deformation of the turbine blade during investment casting, a novel compensation method based on reverse deformation was proposed in this study. The article investigates and evaluates critical points for deformation of the blades after their production on wax-press machine. In addition, the effect of the pre-deformation preparation and the human factor influencing effect during assembly is evaluated with the main aspect of not machining all surface of small blades.

The paper deals with the strength conditions assessment of new design of modern railway bogie through FEM analysis. The bogie, which was developed as part of European structural funds project, is characterized mainly by better dynamic properties while driving on the track, higher safety against derailment and lower negative effect on the track (reduction of wear). For analysis of bogie frame, there has been created a substitute simulation model. Results from calculations and prototype tests prove, that investigated design of new construction satisfies strength conditions.

The paper deals with the design of a special machining tool for efficient production of detail on the T-groove of the clamping part. The introductory part of the paper is focused on introducing the Czech company. The practical part of the paper deals with the analysis of the existing state of machining of the clamping body and of the production of the T-groove detail and proposes an innovative solution in the form of more efficient machining process (partial production modification), which consists in the development and production of a special tool with replaceable inserts. The main reason for this partial modification is a significant reduction in unit machine time in the production of the T-groove detail on clamp body parts. Part of the contribution is in the process of streamlining the innovation made in the form of changes to the manufacturing process and the design of the cutting conditions required to produce the T-groove detail on the clamp body parts. The contribution is completed by a technical and economic evaluation, which is related to the analysis and comparison of both proposed production variants in terms of machine times, tool consumption / replaceable inserts and total production costs for the T-groove detail production on the clamp body parts.

The main aim of this article is to show the possibilities of using tram windscreen impact tests in the analysis of human-machine accidents. Empirical experience shows that these accidents especially affect the head, which is at the same time one of the most vulnerable parts of the human body. Windscreen safety testing follows ECE standards and, inter alia, involves collisions with a headform. With regards to numerical simulations, however, it is essential to be able to determine the material characteristics of windscreens. Here it seems to be advantageous in terms of validity, reliability and the economic cost of using collisions with a rigid body where only the glass absorbs all of the kinetic collision energy. The outcome of these tests is a waveform of the cont act force's magnitude as a function of deformation in the direction the force acts. Along with the time course of acceleration of the bumper and its kinetic energy on impact, this information can serve as boundary conditions to verify mathematical models.

The aim of this experiment was to investigate the influence of the Sr modifier in the Al-Si eutectic alloy on the structure change and its mechanical properties. For this reason, an Al-Si7Mg0.3 hypoeutectic silumin alloy was modified with the aim of improving the mechanical properties of the material, mainly by increasing the ductility and strength. The subject of investigation was analysis of morphology of excreted eutectic silicon. In order to investigate the surface, metallographic cross-sectional specimens were prepared using light and electron microscopy. A static tensile test was performed for detailed examination. It has been found that the addition of the AlSr10 modifier and, over the time of modification of 1 to 2 hours, has increased the mechanical properties, in particular the ductility.

The use of cutting fluid should positively influence on the quality of the machined surfaces and durability of cutting tools. However, during the machining the oil from the hydraulic system of the machine often gets into the cutting fluid, which can alter the properties of the cutting fluid. In scientific literature there is no information about the effect of the hydraulic oil entering the cutting fluid on the tool life and roughness in turning. In this regard, at the laboratory of the Department of Machining and Assembly of the Technical University of Liberec, there has been conducted a study to ascertain the effects of hydraulic oil getting into different types of cutting fluids during the turning of stainless steel.

Microcellular injection molding is relatively new and progressive technology for production of lightweight constructions. The weight reduction, elimination of sink marks, internal stresses and deformation of products are the main advantages of this unconventional technology. On the other hand, decrease in mechanical properties and poor surface quality are the application restrictions. There are several aspects affecting formation of microcellular structure and final properties of injection molded products. As a one of the most important aspects there is used material. Therefore, the main goal of this article was investigation the influence of different types of thermoplastic materials on the microcellular structure formation and mechanical properties of products. Further, the influence of holding pressure on products quality was also evaluated.

An intensive abrasive wear of agricultural machines and their parts occurs at the soil processing. An undesirable change of a tool surface occurs owing to the wear. Namely ploughshares of a plough are intensively abrasive worn. This undesirable change leads to a function loss. The paper deals with an evaluation of the ploughshare service life. The aim of the research was to evaluate the wear of the ploughshare with a layer of a carbide hardfacing OK Tubrodur 15.82 deposited on a bottom side of the ploughshare. The research was performed within a laboratory testing (a hardness HV30 and a wear) and field tests. Laboratory experiment results proved that the overlay material showed a significant increase of the wear resistance and the hardness. These conclusions of the laboratory testing were certified at the field tests. The research results certified this procedure as an efficient solution at the decreasing of the ploughshare wear at the ploughing.

The article deals with the measurement of conveyor belt noise and vibration. The conveyor belt was supported on six rollers fixed on three plates of stand, return and drive drum. These six rollers were produced in two sets (convectional tube and accurate tube). Rollers were driven by a rubber belt. The noise was measured and evaluated on both sides of the conveyor. Vibration of the conveyor was measured at four locations of the conveyor construction. All measurements were performed in an unloaded condition. In conclusion of the article is a summary and evaluation of all measurements. The vibration of the conveyor is comparable in both cases, however, the rollers from accuracy tube excite the construction less, and this results in a lower total noise. By comparing the acceleration to the dominant frequency, it is obvious that the noise and the vibration of the belt conveyor construction were reduced by using rollers from accuracy tube

Presented research paper is focused on the development of carbon fibre wheel. Considering development and construction of wheels for the automotive and motorcycle industry, low weight is one of the most significant factors. In the case of rotating components, the imbalance of the assembly is a problem. This fact affects handling of the vehicle or wheel behavior under the load, for example in the point of turning, acceleration or drive on damaged road. Determination of the most appropriate material composition (sequence) is primarily the main problem of composite material application. Correct design of material composition and also lay-up diagram is determined by material characteristics and strength requirements. A suitable solution is in the application of a group of input material structures creating hybrid composite. Specific combination of various input materials (aluminum ring, 3D printed plastic honeycomb core and carbon fibre composites) guarantees and ensures the fulfilment of the strength requirements which are determined during each particular application. The main aim of presented paper was to design material composition and shape of carbon fibre wheel that were subsequently verified by successful manufacturing process.

Drawing process is generally influenced by many technological parameters (e.g. holding pressure, friction coefficient, etc.) and all of them should be considered for numerical simulation of such process. This paper deals with the possibilities how to determine one of the parameters that is quite difficult to be taken into account - magnitude of heat generated during forming process. In this case only heat generated by plastic deformation was determined, thus static tensile test at different loading rates was performed. Contact-less optical system ARAMIS and Thermo-camera FLIR SC660 was used to measure distribution of both plastic deformation and temperature on samples surfaces.

Present work is focused to determine the cause of higher wear of castings made of secondary (recycled) AlSi12Cu1 cast alloy after switching supplier and the morphological evolution of Fe-rich phases has been documented. As recycling of Al-alloys becomes more common, sludge will be a problem of increasing importance due to the concentration of Fe, Mn and Cr in the scrap cycle. The tendency of Al-Si-Cu alloys to form sludge Fe-rich particles can be predicted by the sludge factor (SF) equation, which represents an attempt to gather the combined effects of Fe, Mn and Cr. Sludge phases are hard and brittle phases which can compromise the machining operations, with a considerable effect on the cutting tool life, and even more degrade the mechanical and physical properties of the component. For study and identification of intermetallic phases' was utilized standard etching (Dix -Keller, H2SO4) and for element composition was used X-ray analysis. The results show that coarse sludge Fe-rich phases appear in the alloy with 0.945 wt. % Fe combined with higher content of Cr, while the Chinese script or needle-like Fe-rich phases appear combined with Mn. At the same time, a higher sludge factor was calculated and the ratio between the amount of Fe and Mn was not respected.

The combustion engine is a very widespread energy source for many machines and devices. Diesel, gasoline, LPG, CNG, as well as many biofuels such as ethanol, butanol, etc. are used as propellants at the present time. During the running of the internal combustion engine, some fuels penetrate into the crankcase and degrade the engine oil. This potentially reduces the lubricating ability of the oil and changes its degradation process. Submitted paper follows possible changes in lubricating capabilities of oil used in engines with specific fuels: n-butanol, LPG and diesel. Different type of fuel used in combination with an inappropriate operating mode might have a significant influence on the oil and consequently on the engine wear (monitored by a laser particle analyzer). This paper also deals with presence of various types of particles in the engine oil. Results demonstrate proceeding changes noticed in oil and also how was the degradation process effected.

The main aim of this experimental paper is investigation, analyzing and realizing the experimental measurement of cutting temperature when external turning of rotational parts made from AlCu3MgMnPb aluminum alloy. In this experimental study a number of turning tests have been carried out by using a test lathe and a cutting temperature measuring device. This measurement have been successively investigated and experimentally verified with the special samples (in experimental measuring of the temperature during the turning process of samples and measured results designated with special thermal camcorder type FLIR used for special measurement of cutting temperature). The theoretical contribution of the realized experiment is the finding that the change of cutting speed, depth of cut, feed motion and cutting temperature increase with increasing of the chip emerging influence factors change over time. Practical benefit is recognition that the emerging shape of the chips in turning of aluminum alloy is a consequence of the deformation process, which depends on the measured sample from its crystal structure and the conditions under which the deformation process occurs mainly by the deformation, cutting speed and temperature.

In this study, cutting forces experimental measurement an analysis with special carbide insert when turning austenitic stainless steel have been investigated. Stainless steel X5CrNi18-10 is often considered as poorly machinable material. In this experimental study a number of turning tests carried out by using a test lathe and a cutting force measuring device are presented. Accordingly the effect of cutting speed and tool insert cutting geometry on cutting forces in turning austenitic stainless steel X5CrNi18-10 (AISI 304) using Wiper cemented carbide tool insert has been discussed. The effect of cutting parameters (feed rate, depth of cut) is also analyzed by cutting forces measurement. The input parameters were varied as vc = 100 m.min-1, f = 0,150 and 0,275 mm and edge geometry r = 95°, r'= 5°, εr = 80°, rε = 0, 8 mm, s = -6°. The results show that main cutting force Fc decreases with the increasing of cutting speed in turning without using the coolant. A benefit for production process also confirmed fact that this growth is 2,5 to 3 times higher as for turning of CS0E4 under the same machining conditions due to the hardening of austenitic steels for chip creation. It was also noted that experimental specimens showing larger cutting forces then generated worse surface finish as well as larger surface damage.

Aluminium is widely represented material in engineering - one of the possible forms of application is an Al powder, when mutual interaction mainly with polymer matrix creates new materials. In practice, the aluminium powder is commonly used together with a number of reaction resins, e.g. epoxy resins. Such systems can be described as liquid metals, and amongst other options of the application, they are used for quick renovation of the functional areas of machines. In such applications, particularly important are hardness and durability of the composite layer against wear. This paper experimentally evaluate the friction and wear of systems based on epoxy resin with aluminium powder (microparticles), through reciprocating sliding tribotests. Tribological outcomes evidenced a reduction of the friction coefficient when the resin is reinforced by alumium particles, with a concentration of 32% in term of volume fraction.

Hot tears represents serious defects, which are in most cases considered as unacceptable and may even result in disposal of final casting. The cause hot tear initiation is mainly a combination of several mechanisms (incorrect mold construction, chemical composition of used alloy, purity of used alloy, casting process conditions etc.). Basic principles of hot tears initialization can be considered relatively clarified, but a comprehensive and coherent view is still missing. The goal of proposed project was to design a coherent system to analyze emerging hot tears in the aluminum castings. The proposed mechanism is based on a number of concepts - a combination of "dog bone" and "T-section" tests. During the experiments will be possible to record the temperature at critical points, a tensile force in shrinking casting and by using heat-resistant glass placed above the heat node will be possible to directly observe the tears. Initial experiments will focus on verifying the functionality of the apparatus, the aim will be to analyze the impact of the solidification interval on hot tears.

An adhesive bonding technology is limited by a cyclic loading of an adhesive bond. The paper deals with a testing of a low-cyclic fatigue of single-lap bonds reinforced with glass beads (B159, a fraction size 90 ± 20 μm). The aim of the research is a study of a low-cyclic behaviour of structural adhesive bonds by means of a scanning electron microscopy (SEM). The research will contribute to a clarification of the fatigue behaviour (low-cyclic) of structural adhesive bonds. The aim of the study was to evaluate a service life of the adhesive bond in terms of its fatigue loading at a low-cyclic shear test. Values of a pulsating loading for the low-cyclic fatigue tests were chosen from this reason for tested adhesives from static tensile test determined a reference value of a maximum force gained at a statical test according to the standard CSN EN 1465. The number of cycles was 1000 at the 30 % strength reached at the static tensile test of the adhesive itself. The cumulative effect of the shear cyclic loading after 1000 cycles showed micro- and nanocracks in the area of the adhesive. The experiment results did not confirm the assumption that repeated cyclic loading could lead to the premature failure of the adhesive bond.

The paper presents results of experimental investigation of steady flow in the region of common carotid artery (CCA). The CCA bifurcates into two branches: into internal carotid artery (ICA) and external carotid artery (ECA). ICA, that supplies blood to the brain is enlarged. This region is referred as the carotid sinus. In the present study, three models of the carotid artery bifurcation have been manufactured. The models vary in geometry of the carotid sinus. Their effect on fluid flow has been investigated under steady flow condition, utilizing Particle Image Velocimetry (PIV) and flow visualization. The flow conditions approximate physiological flow. The measuring range of Reynolds number was from 400 to 1300. Experimental results indicated the effect of carotid sinus geometry on the main flow in common carotid artery.

The article deals with cyclical abrasive wear of the surface of forming tools. At this stage the research focused on the genesis of stress in the contact between a deformed material and a tool in the cold bulk forming process. The experiments were conducted in the simple configuration of the upsetting test. The article presents the results of abrasive wear by a combination of materials of examined samples and upsetting plates. The abrasive wear in the used material specimens was analysed comparatively in the form of the wear factor by the finite element method. Two intersecting phenomenological fields represent the output for the examined material combinations. Firstly, it is a formulation of the dependencies of the maximum depth increase of the surface wear. The argument is the number of exposure cycles. At the same time, the topology of degradations and the resulting roughness in the space of the exposed surface were examined.

Failures of machines are caused by variety of external and internal effects and process that cause ultimately interruption of operation. These factors have resulted in changes of properties of machines parts and these changes are the first causes of technical failures. Wear is one of the major factors that contribute to the creation of failures and with this is connected generation of wear particles. Wear particles come into oil in lubrication system, where they cause contamination and degradation of lubricating properties and consequently it may result in major failure of machines. Among these contaminants are included mainly adhesive, abrasive and fatigue particles wear. The paper describes number and morphology of wear particles generated during modified Reichert test (friction pair - steel and aluminium alloy) analysed by LasetNet Fines device. Experiment also compared capability of lubrication of four different engine oils exposed to various weight load.

Repairs of branch connections defects on high-pressure pipelines allied to gas-escape are nowadays difficult processes. The reason is necessity of performing sections of damaged pipeline that is connected with transport medium layoff or with using technology of by-pass installing around damaged part of pipeline. In article, a concept of technology of branch connections repairing by split pressure sleeve is presented, which is in recent times realised only at straight sections of pipelines. Concept consist of split sleeve design along with wall thickness optimization in simulation software ANSYS. Concept of internal space of sleeve sealing up from welding workspace using appropriate seals placed at its sealant carriers is presented, too. Dimensions, material of carriers and sealant location were designed according to experimental measure of temperature, together with subsequent validation of heat transfer by numerical simulation in software SYSWELD. Described repairing method concept seems to be an appropriate alternative of branch connection repairing that allows fast and safe correction with lowered operational costs on realisation of repair and possibility of speeding-up and simplifying emergency conditions solution.

Thanks to their chemical and mechanical properties, the process fluids (PFs) can significantly affect the process of machining [2], [15], [16], [18]. It is particularly important that PFs should positively influence the quality of the machined surfaces of machine parts and durability of cutting tools [4], [5], [6], [7], [10], [11], [12], [14]. Other significant factors in PFs are economic and environmental [17]. The costs of the acquisition, use and disposal of PFs must not be too high. As part of the research project in collaboration with the company Paramo, a.s. and the Technical University of Liberec, completely new environment-friendly PFs (labeled as PF01, PF02, PF03, PF04, and PF05) have been developed and evaluated. In the Laboratory of Machining at the Technical University of Liberec, the effects of these new PFs were examined from a viewpoint of a number of technological aspects. This article presents the results of experiments conducted on structural steel 16MnCr5 and stainless steel X2CrNiMo18-14-3 face milling using these newly developed eco-PFs.

This paper deals with the preparation, composition and mechanical resistance of inorganic-organic nanolayers with built-in hydrophobic groups through sol-gel synthesis. The components of the nanolayers are 3-(trimethoxysilyl)propyl methacrylate, tetraethyl orthosilicate and hydrophobic chains - hydrocarbon chains in the range of 8 to 16 carbons. The study is aimed at evaluating the mechanical properties of prepared nanolayers with different hydrophobic chains compared to a reference sample without any hydrophobic groups. An abrasion resistance test was performed on several selected nanolayers with the best hydrophobic and antifouling properties. In the framework of the research, nanolayers prepared with polymerization achieved by heating at 85 °C or 150 °C were compared. The best mechanical properties and hydrophobicity of prepared nanolayers was AF12 with a hexadecyl hydrocarbon chain polymerized at 150 °C. These nanolayers are suitable for marine, underwater or any other hydrophobic application results from performed research.

When a micro-hole of high aspect-ratio is required, in addition to machining problems, special attention should be paid to controlling the quality of the manufactured products. Dimensional and surface metrology in the field of micromachining can be as critical as machining itself, therefore several new measurement methods have been developed. However, many of these methods suffer from application limits when used in the case of a deep hole. Replication can be a useful approach, which has well-proven validity in the time-consuming case of the sectioned hole. The method of through replicas, to be pulled out of the unsectioned hole, still needs verification.
In the present paper, the surface roughness of deep small electrodischarge drilled holes is measured, and the effectiveness of the use of both open- and through-replicas is evaluated, versus direct measurements on the micro-drilled surfaces. Through-hole replicas, by means of injection and extraction of a silicone, are proven reliable for reproducing the surface morphology of holes down to 0.8 mm diameter with an aspect ratio of 12.5. The findings show that the operative range of the considered techniques may be extended with respect to the previous cases mentioned in literature

The aim of this article is to calculate and compare the modal properties of the frame of the standard and modified freight wagon bogie design. Analysed frames represent the main support parts of the bogie, which are most often used in the Central Europe region. Determination of the modal properties belongs to the fundamental but very important step in the engineering design. In our case, modal analyses of bogie frames structures were carried out using the Finite Element Method. In order to perform numerical calculations based on FEM approach, Ansys package was used. Modal analyses of individual parts as well as substructures of rail vehicles is an inseparable part of the rail vehicles design process. In this article theoretical and practical consequences of obtained results from the modal analysis, i.e. eigenmodes and eigenfrequences of the analysed part of the bogie on its dynamic properties are presented.

Special attention is taking place in the environment of public transport, for which higher amount of small radius curves being applied is specific. The outcome of such operation of vehicles is an increase in vehicle's effects on the track in the rail-wheel contact resulting in increased ride resistance, creep in the rail-wheel contact patch, speeding up the process of wear in the contact pair as well as noise generation. At present, a variety of technical solutions for the vehicle bogie design as well as track designs focused on decreasing of these negative effects exists. Their use in smaller radius curves however, cannot give acceptable results and often causes complications in bogie design. The authors give a concept of creep reduction in rail-wheel contact by using double wheel tread, which doesn't require complicated bogie design. The proposed solution is supported by dynamical simulation of the tram car vehicle ride with considering of active wheel tread changes, and is also registered under Patent Application Nr. a201701589.

In this paper, the results of an investigation done with face milling are presented. The changes in cutting force and surface roughness were studied through changing the values of depth of cut and the feed per tooth. Meanwhile the permanent value of the undeformed chip cross section, which was determined (fz and ap), remained permanent. Increasing fz and keeping the same value of Ac chip cross section, the ratio ap/fz changed in five grades from 0.5 to 8. It is shown, that if the feed is increased in the examined range so that the chip cross section is constant, then the value of the cutting force decreases, which decrease can be observed in all three force components. Accordingly, the mechanical power required for cutting is reduced. The results of the surface roughness investigations showed that initially a significant increase can be observed in the roughness with the gradual increase of the feed (up to ap/fz = 2.5), followed by a moderate increase afterwards.

Using of cutting inserts is currently a normal part of the manufacturing process. The article deals with analysis of tool wear after machining at one selected cutting insert. Evaluation of this insert was made by electron microscopy. There was used SEM and EDS analysis. For this purpose was used scanning electron microscope Tescan Vega 3 and EDS analyzer Bruker 16 which is part of this microscope. These analysis can provide a good picture of the structure and construction of inserts, their composition and for situation on the insert after machining. This may assist in finding suitable cutting conditions. As experimental material the hardened steel class 16MnCr5 according to EN 10027-1 has been machining. SEM images of final tool wear of the cutting insert were recorded. The reason was to map the tool wear state after machining using electron microscopy to give a better view of the situation. These analyzes were performed in other experiments performed at the Faculty of Mechanical Engineering at Jan Evangelista Purkyně University in Ústí nad Labem.

The paper deals with the proposal for the production of an assistance brake for a mechanical wheelchair, which will help the wheelchair users to move in the course of overcoming barrier-free and partially barrier obstacles. The introductory part of the contribution characterizes the basic requirements of the brake for a mechanical wheelchair, especially from a legal point of view and in terms of their safety. The practical part of the paper deals with the production of a prototype pair of assistance brakes in school conditions (workshop C2 of the Institute of Mechanical Engineering, Faculty of Mechanical Engineering, Brno University of Technology) using conventional machining technology (brake body production) and 3D printing technology (braking segment production). Part of the practical part also requires testing in typical / real wheelchair conditions. The contribution is completed by the technical and economic evaluation of the prototype pair of assistance brakes, which is related to the calculation of the total cost of their production.