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The objective of this work is to assess cutting speed during the wire electrical discharge machining (WEDM) depending on the machine parameters setting (gap voltage, pulse on time, pulse off time, wire speed and discharge current) and follow-up assessment of the surface quality achieved. In order to achieve efficient machining the maximum cutting speed is required, however maintaining of the required quality and functional characteristics of the machined surface must be considered. Surface morphology during the wire electrical discharge machining is formed by a high number of craters, of which depth has direct effect on area parameters and profile parameters of the surface quality. These parameters were evaluated using Contactless 3D profile-meter based on the principle of coherence correlation inter-ferometry IFM G4 from the Alicona producer.

The article presents investigation of the trybological properties, particularly dry friction and friction using a process fluid, of friction pairs of steel ball against titanium-aluminium base nanomultilayer (NML) coatings. The coatings are deposited by cathodic arc evaporation of both pure titanium and aluminium with eighteen percent silicon cathodes. Each multilayer structure consists of 49 bi-layers. The external deposited layeris with five times longer growing period. The coatings are deposited at the temperature of 400°C and the work pressure of 2 Pa. Polished steel discs (Ø 20 mm × 5 mm thick) are used as the substrate material. The measured dry friction coeficients are in the range of 0.216 - 0.356 and the coefficients friction using process fluid is in the range of 0.085 - 0.151. The calculated wear of the counter-body is in the range of (0.66/ 4.21)×10-3 mm3, asit depends on the friction conditions and the used multilayer coating.

Many materials of general interest, which they are frequently employed in common life, industry, biotechnology, tissue engineering studies, medicine, have many excellent properties, but their inert nature may limit their wider usage in some cases. Many modification techniques have been therefore developed to improve surface properties of variable substrates for other applications. For a long time we study surface properties of a wide range of substrates (polymers, glass, silicate powders, etc.). Surfaces of studied materials are firstly activated by chemical or physical ways and than variable chemical compounds (e.g. nanoparticles, nanostructures or nanolyers) are grafted or deposited on. Surface properties are characterized before and after individual activation or modification steps by many techniques (microscopies, spectroscopies, goniometry, electrokinetic analyses, X-ray diffraction, etc.). Some of tested samples are also tested for antimicrobial activities and/or for cell adhesion and proliferation for their potential usage in tissue engineering. This paper presents a survey of techniques for preparation of nano-structured materials for usage in electronic, optics or medicine and selected results.

One of the main problems in machining Al alloys represents built-up edge formation. This paper is focused on the effect of selected modifiers in AlSi7Mg0.3 alloy on built-up edge formation. Four variants of castings modified by strontium, calcium and antimony are used. All these alloys are compared with non-modified alloy. Built-up formation leads to the increasing of surface roughness for both types of built-up edge - unstable or stable. If unstable built-up edge is produced, surface roughness increases enormously. Therefore the research is focused on surface roughness in different cutting conditions. There were moulded castings of non-modified alloy and for each modified variant. Gravity-die castings into a metal mould with a thermal insulation were made.

These days are more and more posing claims for the highest quality of castings from the aluminium alloys and for the lowest weight of these castings. Thus for complex material (in this case alloy) utilization it is very important to monitor its behavior both during production (chemical composition, metallographic evaluation of the structure, observance of thermal treatments temperatures, refining and degassing of melt and so on) and also during its loading. This papers deals with the monitoring changes of stress on the testing samples surface arising from the force loading. As a loading there was a bending momentum at the testing samples (rods) from the alloy AlSi7Mg0,3 which was poured into the metal mould after the different thermal treatment methods. Bending momentum increased up to the expressive deformation of the tested sample. Results were also completed by the depth profile of the residual stresses which were measured by means of the X-ray diffraction (X-ray tensiometry analysis) namely for all thermal treatment methods. Moreover in the depth profile there was also performed the qualitative evaluation of the structure by the back-reflection Debye-Scherrer method.

Resistance welding ranks among progressive and in practice often used manufacturing techniques of rigid joints. The basis of this method is in the utilization of the Joulean heat, which arises at the passing of current through jointed sheets at collective influence of compressive force. The aim of the carried out tests has been to evaluate the rupture force of spot welded steel sheets of various thickness using short-time spot welding and long-time spot welding. For test specimens welding the parameters recommended by the spot welder producer were used. After welding all assemblies were loaded using the universal test machine up to their rupture. The rupture force was written down. From the carried out tests it follows that welding of sheets of the thickness 1 + 1 mm, 1 + 2 mm, 1 + 3 mm, 1 + 4 mm and 2 + 2 mm the rupture force value differences of short-time spot welding compared to long-time spot welding are practically negligible. But at the specimens of thickness 2 + 3 mm, 2 + 4 mm, 3 + 3 mm, 3 + 4 mm and 4 + 4 mm considerable differences were determined. The part of this tests evaluation was also the assessment of the tested assemblies failed pieces.

Currently, traditional materials are very often replaced by composite materials in many industrial areas. The advantages of these materials consist mainly in their lightweight, high strength and flexibility, corrosion resistance and a long lifespan. The use of composites reaches its large development in the field of aerospace. This article discusses quality of the manufacturing process technology of a specially shaped composite frame in 3D space. The used technology is based on a winding of carbon, glass, organic filament rovings on a polyurethane core. Polyurethane core which is a geometry of frame with and without a circular cross section. Quality production of said type of composite frame depends primarily on the correct winding of fibers on a polyurethane core. It is especially needed to ensure the correct angles of the fibers winding on the polyurethane core and the homogeneity of individual winding layers. The quality of fibers winding also depends on the material properties of polyurethane core and fibers. The article describes mathematical model for use an industrial robot in filament winding and how to calculate the trajectory of the robot. When winding fibers on the polyurethane core which is fastened to the robot-end-effector so that during the winding process goes through a fibre-processing head on the basis of the suitably determined robot-end-effector trajectory. We use for description numerical model and matrix calculus to enumerate the trajectory of the robot-end-effector to determine the desired passage of the frame through the fibre-processing head. The calculation of the trajectory was programmed in the Delphi development environment. Equations and relations of the numerical model are important for use a real solving of the passage of a polyurethane core through fibre-processing head.

At design of cutting tools the positioning of cutting edges and geometry of cutting inserts are becoming increasingly diversified with the development of cutting procedures. As a result, the generated tool marks on cut surfaces also can take many forms. Roughness values in face milling can change both in planes parallel with the feed direction and in planes at angle to it, therefore it is particularly important to be able to plan the roughness characteristics of surfaces. A new method is introduced in the paper for planning the roughness characteristics of cut surfaces that can be used to determine theoretical values of roughness characteristics of surfaces generated by tools having defined edge geometry. It is based on CAD modelling of the theoretical cut surface; practically any complex tool geometry can be modelled and 3D roughness parameters determined. In application of rotating tools a variety of tool designs and setting accuracy were taken into consideration during the determination of theoretical values for the simultaneous cutting of more than one edge. An example is shown for two different insert geometries.

According to the uniaxial tension model and coulomb friction theory, by considering the nonlinear mechanical properties of rubber, the effect of deformation quantities of silicone rubber rectangular sealing ring on the assembly torque in tightening assembly process is researched in this paper. A stress-strain numerical model of silicone rubber rectangular sealing ring in small deformation range is established when tightening, on this basis, the numerical model is derived in deformation quantities of rectangular ring and assembly torque. Then having the torque-angle experiments by automatic tightening machine. The results show that, compared with the practical engineering experiment, the numerical model that reveals the relationship between the deformation quantities of the rectangular sealing ring and Assembly torque can reflect the effect of deformation on the assembly torque during the actual assembly process with great accuracy, which has a great reference value for the automatic assembly.

In the paper, results of a research on influence of piston stroke rate on structures of AlSi9Cu3(Fe) (EN AB-46000 group) castings manufactured at constant intensification pressure of 290 bar are presented. Relation between piston speed (0.3-2.3 m/s) and casting structure was evaluated after a series of trial high-pressure castings. The examinations were carried-out on properly prepared samples taken from the castings in places with the largest cross-section area. The effect of pouring rate was evaluated on the grounds of metallographic observations on a light microscope and a scanning electron microscope. It was found that larger grains of the very hard phase solidify at low piston speed between 0.3 and 0.75 m/s. Higher piston speed results in finer casting structure and in refinement of particles of intermetallic Fe-Mn phase, which is beneficial for usable properties of the castings.

This article deals with the evaluation of changes in mean values of the individual components of cutting forces and measuring the roughness parameters after machining variable cutting conditions such as cutting speed and feed rate. Were evaluated 3 materials from different classes' machinability: steel 14109, alloy CuZn40Pb2 and brass AlCu4PbMg. The materials have been chosen with respect to their use in the extrusion method of the ECAP. The experiment was carried out on the machine SUI 40, the forces were measured on a dynamometer KISTLER 9441 and on the roughness equipment Hommel Tester T2000. All measurements will be evaluated in tables and graphs. The results could be used in abbreviated testing machinability as indicative.

Residual stresses significantly affect the life of parts material, especially in bearing manufacturing, where the stress introduced into the material in the manufacturing process affect the component throughout its whole operating life. It is therefore important to know the size and orientation of these stresses and to optimize the production process of the bearing rings, in order to eliminate as many of these undesirable stresses. The subject of the article is chosen at demand of practice and has to correlate coating cutting tool for residual stress and microstructure in turning the outer bearing rings made of material 1.3520, which is widely used in bearing production. Turning cutting tool WNMG 080408E-M was used with two different coatings. We conducted measurements on a X-ray diffractometer. We measured normal stress parameter and the FWHM (full width half maximum at), which is decisive, and it is related to the grain size of the material. We found that the residual axial stress approaching the zero value, depending on the etched layer.

This paper deals with detection of surface burn after grinding operations on bearing rings made of case - hardened steels. The paper reports about Barkhausen noise technique employed for non destructive monitoring of grinding burn and discusses the main aspects affecting the Barkhausen noise emission such as thickness of heat affected zone, micro hardness, stress state, carbides, dislocation density and volume of retained austenite. Results of experiments indicate that the influence of stress state on Barkhausen noise is only minor whereas influence of structure features dominates. On the other hand, it is difficult to unwrap influence microstructure features contribution to the Barkhausen noise. For this reason their influence should be studied on the model surfaces undergoing the different regime of chemical and heat treatment.

In this paper the mechanical behaviour of structural two-component epoxy adhesives in T-joints is experimentally investigated. Laboratory experiments were performed on standardized test specimens of structural carbon steel S235J0 made according to standard ČSN ISO 11339.
The aim of experiments was to confirm or disprove a hypothesis about a possibility to increase the adhesive bond peeling strength by means of an interlayer from glass fibres.
The research was focused on an effect of an improving a resistance of the adhesive bond stressed by peeling by adding an interlayer created by fabric from glass fibres. The testing of these properties was performed in accordance with standard ČSN EN ISO 11339. An epoxy resin was used as the adhesive for connecting adherents created by sheets of steel. The fabric from glass fibres of the type E in a plain weave was added as the reinforcement for creating the composite bond. For optimization of properties of the composite bond it was used various weight in grams of fabric in the extent of 80, 110, 160, 220 g/m2.

Solid Rocket Motor (SRM) is a key component for the missile and space rocket. Sealing performance is an important index for SRM assembled. It is a necessary condition for study on the sealing performance of SRM to determine the residual stress of sealing ring which is difficult to be obtained by direct detection in engineering practice. This paper derives the quantitative expression of the relationship between residual stress, pressure difference and preload stress and establishes the method of determining residual stress of sealing ring by mechanical analysis. With the help of experiment, verify the correctness and applicability for expression meanwhile, analyze the influence of SRM's types and rubber sealing ring materials on residual stress changed under the effect of pressure difference. Therefore, the method of residual stress determined provides theoretical support to improve the SRM assembly process and lays a foundation for later study on the leakage rate of SRM.

In order to have a good performance of gas exchange in working process, a function of six order polynomial dynamic cam was established in this paper. The influence of the maximum ample factor to valve including the maximum positive and negative accelerations and the minimum curvature radius was analyzed by NLPQL. On this basis, multi-body dynamic analysis for diesel engine valve train was done, valve train dynamic model was established by ADAMS, multidisciplinary optimization process of cam profile and its model was put forward, and ISIGHT software was used to optimization and calculation. Finally, a set of different cam parameters and corresponding valve performance parameters was established, multipart integrated design and multidisciplinary optimization for diesel engine valve cam was realized. This paper provides a new method for the multicomponent integration design and multidisciplinary integration optimization for diesel engine valve train.

The article defines the specifications of engine oils used alternative fuels. Used particle analysis of exploited oils gives the results of the wear mode, which indicates the ratio of large and small wear particles contained in exploited oil. Another very important result is defined as the level of wear, which indicates the amount of wear particles contained in exploited oil. For the level of wear Thin Layer Chromatography was used. It was possible in practical terms to apply discriminant analysis based on the results of these tribodiagnostic methods. Nomogram the wear receives practical information of current oil and engine wear. On oil life and operational reliability of gas engines affected by the choice of oil, according to the specifications. Another parameter is the mode of operation of the engine and preventive maintenance. The results of the oil wear were significantly different and depended just on the current state of the engine. For engines in perfect condition low values of wear were measured, for engines in poor condition critical wear was detected.

The manufacture of die forgings from Al-Mg-Si type alloys is one of important topics of material and forming technology development. One of innovation factors affecting the forging technology is based on the use of continually cast rods instead of extruded ones. This change of technology is, however, connected with some problems concerning the structure, an inhomogeneous surface layer, surface morphology of cast rods and increased flow stress of the cast structure as well. The present paper deals with some aspects relating to the inhomogeneity of structure, intermetallic phases and thermomechanical treatment. The investigation of the cast and extruded structure was carried out with the help of optical and electron microscopy.

Even though the thermochemical treatment is thought as a typical domain of ferrous alloys, there exists a series of technically important processes in the case of non-ferrous metals. Thermochemical heat treatment processes can be divided to two main groups to the manufacture of wear resistant layers and the corrosion protection, mainly against the high-temperature corrosion. This paper summarizes current knowledge in this field and describes the realization of the processes and examples of practical applications.

Austenitic stainless steels are widely used for various biomedical applications because of their biocompatibility, high resistance to uniform corrosion and suitable mechanical properties. However, they are prone to local corrosion in aggressive halides environments. This article focuses on the effect of fluoride added to physiological saline solution (0.05 % NaF resp. 0.5 % NaF + 0.9 % NaCl solution) and on the effect of fluoride containing mouthwash (0.05 % NaF) on corrosion resistance of AISI 316L surgical steel. Evaluation is based on results of 42-days exposition immersion tests performed at the temperature of 37 °C (REM observation of attacked surfaces, mass losses of specimens) and on the results of the electrochemical cyclic potentiodynamic polarisation tests performed in the same solutions at the same temperature.

This paper is focused on occupational health and safety hazards in machining processes. Problem is specified on employs and employers. Occupational health and safety is based on legislative regulations. Safety rules are usually formulated generally. But it is necessary to formulate safety rules more precisely for different production processes and even for different production machines. And this has not been fully satisfactory solved, especially from the point of view of the development of machine tools, their automation and also from the viewpoint of the development of cutting materials. In the paper principal occupational health and safety hazard in machining will be formulated on the base of laws, regulations and personal findings of the paper's authors in different enterprises. As an example safety hazards and safety rules will be in depth formulated for turning. Similar health and safety rules and hazards must be formulated for other cutting processes. But occupational health and safety problems relate not only to persons but also to enterprise economy.

In order to improve the transmission efficiency and the service life of ordinary cycloid gear, 5 kinds of new cycloid gears with variable cross section are devoleped based on the principles of traditional cycloid drive. These new cycloid gears include concave cycloid gear, drum cycloid gear, spherical cycloid gear, oblique cycloid gear and cone cycloid gear. The general mathematical equations of these new cycloid gears are obtained and the characteristics of these new cycloid gears in transmission applications are analyzed in detail. A new method on the end milling tooth profile surfaces of cycloid gear using ball end mill is proposed. 5 axis numerical control simulations of these cycloid gears are conducted and the tool paths of machining cycloid gear are obtained. 5 kinds of cycloid gear with variable section are machined on five-axis CNC machining center, which verifies the correctness of the NC program. The study will provide a new way of designing and machining cycloid gear.

The paper deals with the methodology of heat transfer coefficient measuring while using squeeze casting process. The casting with crystallization under pressure was used, specifically direct squeeze casting method. The pressure applied to the melt causes a significant increase (up to ten times) of the coefficient of heat transfer between the casting and the mold. The paper deals also with obtained results of the measured temperatures in the mold and the casting. The goal was to affect crystallization by pressure with value 100 MPa. On the basis of the measured variables were calculated values of heat flux between casting/mold, and consequently also the values of heat transfer coefficient.

The article deals with heat transfer in the casting - mould system. There are characteristics of sand and metal mould. The sand mould is a dispersion system, respectively - a capillary-porous body. In sand mould are heat transfers shared by all three ways: conduction, convection and radiation. These individual elementary processes of heat transfer are only theoretical significance, as very often processes are taking place simultaneously in different intensities or interact. The maximum effects of these processes are in a certain temperature range. From temperature 200 °C dominates conduction heat transfer. Between of temperatures 200 to 600 ° C is the effective convection heat transfere. At higher temperatures above 600 ° C prevails radiation heat transfer. This is the consequence, why the sand mould has a lower value thermal accumulation than a metal mould. The metal mould as a result of its character and compactness has a high heat accumulation value. Therefore, in the metal mould cast solidifies faster than the in sand mould. Based on the Newton's and Fourier's laws, there were indicative calculated times of solidification cast of shape plate in the sand and metal moulds. Concurently were made simulations calculations performed solidification of shaped plate through simulation software MAGMA 5. To obtain the corresponding results of simulation calculations, it is important to use the respective temperature-dependent of the thermo-physical variables, including temperature dependence heat transfer coefficient.

The homopolymer of the isotactic polypropylene (iPP) and the random copolymer of the isotactic polypropylene and 3% ethylene (iPPE) were used in this study. Isotactic polypropylene can be prepared in α, β and γ morphological phases depending on its crystallization conditions. The phase β content has a strong influence on mechanical, optical and thermal properties. The samples with nucleating agents (NA) α and β were used. Various process parameters were used to prepare melted samples: two thicknesses and three different cooling regimes. Wide-angle X-ray scattering (WAXD) and scanning electron microscopy (SEM) were used to investigate the phase structure. The results show that iPP without nucleation agents (4mm,

This study was focused on the analysis of creep behaviour of the polymer composite with continuous phase in the form of two-part epoxies and discontinuous phase (reinforcing particles) in the form of fibres of false banana (Ensete ventricosum). The aim of the experiment was to describe the short term flexural creep behaviour, flexural strength and Charpy impact strength of polymer composite reinforced by fibres of false banana. The fibres of Ensete ventricosum, originally from Ethiopian region Hawassa, were used for this experiment. Reinforcing fibres were prepared in size of length 1-2 mm with randomly fibres arrangement in matrix. The amount of reinforcing particles in the composite material was 0.5; 2 and 30 wt.%. Moulds for casting specimens were produced from the material Lukapren N regarding to the prepared models whose shape corresponds to the technical standard CSN EN ISO 3167. Composite which was used to prepare specimens according to CSN EN ISO 3167 (Plastics - Multipurpose test specimens, English Standard Institution) was created by mixing of fixed rate of matrix and filler.

The paper gives practical using of thermovision for quality casts assessment, which are casting to permanent moulds. Thermovision allows monitoring temperature of moulds and their cooling process by refrigerant medium in foundry engineering. It helps when the problems with elimination internal defects exist. Tests in experiment were implemented by DAS scan and local surface modification of water cores of cylinder heads. Cylinder heads are produced by ROTACAST foundry technology. Results of experiment showed that in location of defects is no directionally solidified. It is necessary to modify tools to defect eliminate. Tests consist of four parts. Each test has its contribution to improve the situation. The last test, when were implemented the heating cartridges was most effective and the problem was eliminated.

An emulation study of the drilling by the spade drill on the spinneret micro-hole is conducted by using FEM analysis software Deform-3D. According to application of finite element software Deform-3D, some characteristic parameter of the work piece and the cutting tool material are set. The distributed situation of cutting force, cutting temperature and tool wear in different cutting parameters are simulated analysis. By discussing the location of the spade drill drilling wear, further optimization of parameters cutting and tool for the spinneret micro-hole drilling provide the better basis.

An article deals with a definition, concept, development, calculation and construction of a prototype solution of a mechanical regulation of a turbine ventilator using a half-flap eliminating an amount of ventilated air. The whole mechanical regulation solution lies in a central shaft. When a rotation nozzle is spun to high revolutions, a flap closes gradually and eliminates air flowing. This prototype of the mechanical regulation may be used for classic concepts of turbine ventilators, where the rotation nozzle stays in one position and only rotates around its own axis.
The article describes individual development stages from the concept up to construction, including a final visualization of the prototype solution of the mechanical regulation of the turbine ventilator using the half-flap. The mentioned innovative solution of the mechanical regulation is very up-to-date thanks to its simplicity and nonservice operation. It is just the matter of time when one of the producers would be interested in the turbine ventilator solution and it would be introduced into a market space.

This contribution deals with the computer simulation and the follow analysis of the rail vehicle running with wheel flat. It comprises of two parts. The first part addresses to the problem of rail vehicle operational, which wheel is damaged. There are several types of wheel damages. In this work the wheel flat problem is introduced. Generally, the rail vehicle running with wheel flat is adverse because the track can be shopworn, some parts of rail vehicle can be damaged and also operational condition for passenger or goods (depending on kind of rail vehicle) can be worse markedly. There is also included a system of forces and accelerations measurement during rail vehicle running on the given track section. The second part includes computer modelling and simulation of this phenomenon. Analyses were focused on the assessemnt of the rail vehicle motion smoothness and its damaging impact on the track. For this, there was created computer model of a twin-bogies passenger car, which the one wheel was modelled as damaged, i.e. wheel flat. Then, there were performed simulations of the rail vehicle running at various speeds. The passenger car was run on the straight track without irregularities in order to avoid adding excitation. Subsequently, values of the vertical wheel forces of the wheel with flat was evaluated.