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Porous titanium-based alloys are very promising materials for medical implants due to their low density and easy osseointegration. In addition, proper porosity and pore size allow adjusting the mechanical properties of implants to values closer to human bone. The aim of this work is to prepare porous metallic biomaterials based on Ti-Si alloys with defined porosity for surgical and dental applications. Alloys were prepared by powder metallurgy using reactive sintering. Best results reached TiSi5 and TiSi10 alloys. The TiSi5 alloy contains smaller pores and achieves lower porosity values. This alloy also has the highest yield strength in compression from these alloys. On the other hand, the TiSi10 alloy is more porous and it is likely to be more suitable for osseointegration.

Aiming at the problem of product family assembly line (PFAL) evolution balancing, an evolution balancing model for PFAL is established and an improved algorithm based on NSGA_II is also proposed. Firstly, the product family evolution and assembly line characteristics are researched and analyzed in big data environment. Tasks on PFAL are divided into platform and personality tasks, and the stability of assembly tasks is mainly considered especially. In the optimization process, a chromosome encoding based on TOP sorting algorithm is adopted, and a new density selection and decoding algorithm is proposed to make up for the deficiencies in traditional algorithms. Finally, an example of PFAL planning is given to verify the effectiveness and feasibility of the improved NSGA_II.

The article deals with hardness tests and dimensional and shape precision analysis of construction and agricultural machinery components, namely with the clamping head and case of hydraulic hammer. The clamping head is made of 41 4220 class (1.7131, 16MnCr5) construction stainless steel and the case is made of 41 5130 class (1.7218, 25CrMo4) construction stainless steel. The micro hardness was measured on VICKERS LM 700 AT hardness tester, according to the national standard STN EN ISO 6507-1: this procedure includes injection of a diamond regular four-bladed pyramid with a 136° peak angle into the tested material with following parameters: objective lens X50, load 10 N, indentation time 10 s. The average HV micro hardness value was determined from 10 measuring points (distances) on 70 samples of the hydraulic hammer case and from 10 measuring points (distances) on 200 samples of the hydraulic hammer clamping head. To measure dimensional and shape accuracy, Perthometer MAHR, equipped with PCV 350 slider unit with sensors with 350 mm length range and a mobile 6-axis 3D measuring arm Romer Absolute Arm 7535 with a working range of 3.5 m were used. This way, basic contour elements were determined: radii, distances and angles. Using the mobile 3D measuring arm, the tolerances of circularity, coaxiallity and perpendicularity were also measured. Technical drawings, contourrograph measuring protocols and tables of dimensional and shape precision deviations are listed in the conclusion of the article.

The article deals with the optimization and modernization of assembly systems by creating models in the simulation software. The creation of digital models is a current trend in enterprise digitization called Industry 4.0. The Tecnomatix Plant Simulation environment allows you to create a virtual model of a real assembly line with the input of its basic production parameters. To perform the analysis, 8 real assembly lines were used, with an average of 15 workplaces, which were integrated into one universal line by means of simulation. The aim was to analyse the effectiveness of the proposed modernization universal assembly line using the generated statistical data.

The paper deals with the evaluation of residual stress in high strength steel sample measured by x-ray method before and after laser welding. Data were collected and processed in program Matlab, where surfaces of stress distribution in the sample were created. Polynomial functions were fit to the data to achieve smoother curves and a better understanding of results. Finally, results of residual stress in the welded sample were compared to those in the non-welded sample for determining the effect of welding on residual stress. Nowadays, the use of high strength steels is being developed, yet their use is sometimes limited by their fatigue critical welds. One common problem associated with welding is the formation of residual stress. Heating, melting and cooling of the weld and nonuniform temperature distribution are causing plastic thermal strain formation, which results in permanent deformation and residual stress near the weld and its heat-affected zone and can be high enough to cause cracking without any applied loads. The welding-induced tensile residual stresses have a harmful effect on fatigue lifetime of structures, corrosion resistance and other mechanical properties. On the other hand, compressive residual stress can improve the fatigue resistance of the material.

The process of developing new universal cutting fluids is labor-intensive due to the requirement of conducting experiments to determine the impact of numerous additives on tool life during different technological operations. Therefore, finding the best cutting fluid, the use of which will result in the longest tool life, is a long and laborious process. To reduce labor intensity while creating new cutting fluids accelerated methods are applied first, such as the method of determining the tribometric properties of a new fluid. Subsequently wear tests are carried out, using only those cutting fluids which show the best tribological behavior.
The aim of this study is to reduce labor intensity in developing new universal cutting fluids. For this purpose, a new accelerated method has been developed, which helps to determine the capability of the fluid to counteract the adhesion between the chips and the cutting tool. Furthermore, a new sequence of cutting fluid tests has been proposed which significantly reduces the amount of wear tests, resulting inconsiderable reduction of the overall labor intensity in the development of new cutting fluids.

The surface quality of ceramic items produced via powder injection moulding (PIM) at processing conditions varying in injection moulding temperature and debinding route is investigated. The analysis is performed on aluminium oxide part design containing complicated rotational areas, where a smooth surface of an internal spiral is a critical quality factor. Surface properties of the final sintered parts are examined with the help of a contactless scanner. Then, the obtained surface roughness data are treated with suitable statistical analytical tools in order to reveal the effect of the processing conditions during the PIM process on the final parts. Relating surface properties of final sintered parts to processing parameters might provide a powerful tool to control particular steps of PIM process.

Polymer composite honeycomb sandwich panels (PCHSPs) are used in many sectors of industry, such as in aerospace, defense and public transport factory. Sandwich panels consist of two facing skins and the core. Products of all industry sectors have to meet requirements on their dependability. This research paper deals with a proposal of the most appropriate methodology for dependability testing of PCHSPs products used in transport industry. Dependability is a global concept that includes terms such as availability, reliability, durability, maintainability, supportability, etc. The experiments have shown S-N curves with damages and without damages of PCHSPs. An important part of dependability is to be fonded the limit states of the studied object, which are for PCHSPs are characterized by fiber cracking and (core) delamination. Dependability evaluation consists of analysis and tests. For every test, it is necessary to be developed its test plan. Facing skin components of the sandwich panels may particularly be damaged. There are several methods of non-destructive testing, which can be used to determine the damage of facing skins of sandwich panels. Infrared thermography (IRNDT) is one of them. IRNDT utilizes thermo-physical properties of the materials, including thermal diffusivity.

In this work, the microstructure and properties of the first-Republic Czechoslovak circulation coins were studied. The variety of the coins at that time was shown. Significant differences in microstructure in the direction of forming and in the normal direction to the surface direction have been confirmed. For some coins, visible features of recrystallization were shown, which suggests the coinage at higher temperatures. The chemical composition of coin alloys was also studied. In most cases, it was consistent with the declared chemical composition by mint. Significant differences in the hardness of the coins were found, which confirmed the different experience of numismatics with the abrasive resistance and the preservation of different coins. The quality of the design and the material composition of the coins confirm the long-standing experience with coinage in the Czech lands, despite the fact that, after the Austro-Hungarian Empire, the mining industry was struggling with big problems (eg stolen raking machines, lack of Czech mining experts). The first-Republic circulation coins represent the best in the history of the Czech and Czechoslovak coinage industry.

Mapping surface quality changes during modification of the cutting tool microgeometry and reflecting on overall quality is the main purpose of this article. A complex view of microgeometry brings together the effects of indvidual stages in the processes which increase the cutting tool properties. The main objective is to increase the durability of the cutting tool. Grinding, microgeometry modification and deposition of a thin resistant layer on the cutting tool are the basic stages during the experiment. These stages have a significant effect on microgeometry parameters. Cutting edge radius, cutting edge symmetry (K factor), roughness of chipping and clearance surfaces are parameters affected by modification processes. Changing individual microgeometry parameters determines not only the surface quality of the cutting tool, but also affects the durability and stability of the cuting process. Appropriate microgeometry modification can make the cutting process more efficient. The combination of process stages and their influence on the quality of the microgeometry of the cutting tool is the primary objective in this article.

This article concentrates on the assessment of a 3D shape of parts of components. The 3D shape is divided into three distinctive shapes: a spherical canopy, a pyramid, and a concave transition between these shapes. Create these shape surfaces, various strategies of 3axis and 5axis milling are used. These strategies are described and then compared on a model in CAM MasterCAM software. The surface of the component is further measured with a roughness measuring device. The accuracy of the surface of the component is measured using a 3D measurement centre and then compared between surfaces with a different machining strategy. The last criterion for comparing machining strategies is to compare machining surfaces with a drawn tool over a pushed tool. Lastly, the best machining strategy is selected for the most suited surface of the component.

The focus at the outset was on nothing more than cryogenic treatment of cemented carbides. Then, in relation to additional findings arising from heating of cemented carbides, this paper was expanded to include the results of heat treatment and the behaviour at elevated temperatures. Although heat treatment is applied to diverse materials, no profound study of heat treatment has been dedicated to cemented carbides. This is despite the fact that both cryogenic treatment and heating to elevated temperatures have been proven to cause changes in their properties. Not all these changes are favourable. If precisely-defined rules are not followed, the changes may be adverse. The interest in heat treatment of cemented carbide has been very low. This paper not only provides comprehensive information on the properties of heat-treated cemented carbides but also presents the processes which take place in cemented carbides under load.

This paper describes selected aspects of design, optimization and manufacturing process of racing car's upright. Uprights described in this paper are formula student car's uprights. Formula Student is an international competition between university students, which must design and build a new prototype of the car each year, according to the FSAE rules. Uprights for most racing cars, formula student cars included, must meet wide specter of different requirements, like minimal weight, minimal stiffness etc. The first part of this contribution is concerned to design requirements and boundary conditions definition problematics like different uprights types. The following parts describe the material selection and possible optimization for the design and manufacture of the new uprights for the formula car. Manufacturing and final assembly of the part will be described.

This article deals with the experimental grinding of cemented carbide cutting tools. Several carbide milling tools with the same geometry were ground under the different grinding conditions and strategy described in this research. The main aim is to determine the influence of the grinding process on the quality of the cutting edge. Different grinding conditions and strategies were used in grinding of the primary radial relief on the peripheral cutting edge. The cutting edge was analysed after grinding by an optical-scanning device and an electron microscope to determine the quality of the cutting edge and radial relief face of the tool. EDX analysis was used for the chemical characterization of the ground surface. The chipping of the cutting edge occurred when the grinding feed rate and the wheel spin direction was changed. The influence of the grinding conditions and strategy on the chipping formation was determined. The mean radius of the cutting edge after grinding was also measured. The results of this work will be used for further research and cutting experiments.

One of the problems in machining Al alloys represents machinability of these materials. Machinability is a characterised by several characteristics. One of these characteristics is a cutting temperature. This paper is focused on the effect of selected modifiers in AlSi7Mg0.3 alloy on this temperature. Several variants of this material modified by strontium, calcium and antimony are used. All these materials are compared with non-modified alloy. Moulded castings of non-modified alloy and for each modified variant were made. Gravity-die castings into a metal mould with a thermal insulation were used.

Several models of FDM machines, characterized by different architecture and hardware components, have flooded the market in the last 5 years. As a result, given the high sensitivity of FDM to the specific machine characteristics, the search for optimal printing parameters is a renown problem. This two-parts paper proposes an easy-to-follow and low-cost procedure for the characterization of any given FDM machine. The method allows the evaluation of the effects of a wide selection of FDM process parameters on the quality of 3D printed parts. The first part focuses on the definition of a series of metrics to be measured on a series of test prints to evaluate the quality of the produced parts. Specifically, several effects are considered: dimensional accuracy, small details, overhang surfaces, ability of printing small holes/thin extrusions and overall quality of the prints. The evaluation of seven quality parameters on a single print is made possible thanks to: i) a specifically designed specimen that is made available to the user and ii) a rigorous and repeatable measurement procedure, which are both discussed in the first part of the paper. The second part presents the characterization procedure, the statistical tools used in the experimentation and provides guidelines to be used for the characterization of any FDM machine. The whole procedure is tested on a desktop FDM machine to demonstrate obtainable results.

The usage of the high-energy electron beam source enables repeated surface quenching of chosen areas of an engineering part surface. Different techniques of electron beam deflection allow creating of hardened layers of different shapes and thicknesses. Experiments were carried out with 42CrMo4 (1.7225) steel. The deflection modes tested were one-point, 6-point, 11-point, line, field and meander. The influence of process speed and defocusing of the electron beam was also taken into account. The electron beam surface quenching resulted in a very fine martensitic microstructure with a hardness of over 700 HV0.5. The thickness of the hardened layers depends on the deflection mode and is affected directly (except field deflection) by process speed. The maximum hardened depth (NCHD) was 1.49 mm. Electron beam defocusing affects the width of the hardened track and can cause extension of the trace up to 40%. The hardness values continuously decrease from the surface to the material core.

This study presents the Resistance Spot Welding (RSW) process of Deep Drawing Steel (DDS) optimization using Response Surface Methodology (RSM) and Simulated Annealing (SA). The RSW process was optimized to obtain the maximum shear force the DDS can withstand. The experiment was conducted under various DDS thickness, welding time and welding current. The experimental processes were conducted using L16 orthogonal array, which has nine rows. The processed DDS was tested using tensile testing machine which will generate the amount of shear force that it can withstand. RSM is first used to develop a suitable mathematical model. The model was tested using Analysis of Variance. From the test result, the model then was used as the objective function of SA. Based on the result, the maximum shear force can be well predicted, which leads to reduced cost and improved welding quality.

In order to successfully acquire knowledge in area of machinery safety for engineering students it is necessary to adopt elementary principles associated with risk assessment. Identification of possible hazards is an important part of risk assessment and engineering students need to take part also in hands-on training to supplement their learning process. It is clear that one major obstacle to improve safety training is the problem of allowing learners to work directly with hazardous equipment. Traditional approach is based on the use of slide show presentations enhanced by animations or videos. This training method is passive in nature and does not allow for an actual realization of consequences resulting from ignoring safety practices during interaction between the student and the machine. In order to improve the educational practice in this context, the Virtual Reality (VR) technologies could be used. The purpose of this study was to conduct a preliminary investigation to determine whether training through VR simulator is comparable to traditional training in developing the skills necessary for performing identification of possible hazards related to lathe operation. The results of this preliminary study suggest that VR based training has the potential to constitute a valid alternative to the traditional training approach.

The field of application of aluminium alloys is very wide and the future use of aluminium alloys is related to the further development of new alloys. Recently, the use of alloys in aluminium alloys is a trend in achieving changes in chemical, mechanical and technological properties. This paper deals with the investigation of the area of calcium influence, especially on the machinability of the alloy. The analysis was performed by alloying AlSi7Mg0.3 with master alloy AlCa10. Four types of samples with different calcium content, from at least 0.1% Ca, up to 1% Ca maximum, were produced. In the case of such samples, research was carried out on the technological properties and especially the workability.

The aim of the article is to verify dimensions of the hydraulic arm column (the necessary cross-sectional area) by analytical dimensional calculation and thus to design a lifting rotary arm which will be located on the pick-up car body (Figure 1). After the analysis of dimensions, the next step is creation of the structure in FEM program and then a numerical analysis will be carried out for verification of stress in the structure already with the values that are not available for the preliminary design (e.g. the structure weight). The next step in the solution will be to import the proposed and by strength calculations checked geometry into the multibody system program, where the dynamic response of the structure will be monitored, depending on the size of the load and the movement possibilities of this mechanism.

A structural studies have been performed on Fe-Al-Si iron aluminides with or without addition of chromium prepared by standard cast process. The effect of chromium addition and subsequent annealing on the phase composition was studied. Very fine precipitates were observed on the grain boundaries in the alloy without chromium addition. On the other hand, complex chromium carbides formed in the structure of chromium doped alloy. The annealing of alloy without Cr addition leads to partial dissolution of secondary phase particles. Unlike the chromium-doped alloy, where the secondary phase coarsed during the annealing process.
The phase composition of the alloys was studied by means of scanning electron microscopy (SEM) equipped by energy dispersive X-ray spectrometer (EDX). The electron backscattered diffraction (EBSD) was used for phase verification.

This paper presents numerical simulation of blanking process using finite element method and comparison of results obtained by analytical solution commonly used in engineering practice. The problem was modeled using axial symmetry. Experimental measurement was used to create multi-linear plastic material model. Results of numerical simulation were used to create history of blanking force vs. tool displacement.

. The paper presents the results of laboratory tests intent on the study of storage place, placing manner and storage time on mechanical properties of briquettes made from poplar chips. For the briquettes production the briquetting press of the firm Briklis was used, type BrikStar 30-12, of 50 mm pressure chamber diameter. All briquettes were made at the briquetting press all parameters constant adjustment. The briquettes properties were evaluated by their density and rupture force determination. Moreover the mechanical durability, the gross calorific value, the total moisture and the ash content were determined. By the carried out tests it was univocally proved that the mode of storage influences briquettes durability at their long-term storage most of all Briquettes, deposited in the well closed plastic bag in closed heated room, changed their properties during four years only minimally. Briquettes, deposited in the same place but in plastic net bag, changed their properties much more. Briquettes, deposited in the well closed plastic bag in closed unheated room, changed their properties during four years only minimally. Briquettes, deposited in plastic net bag, changed their properties to such a degree that they were practically unusable. On the basis of the carried out tests it is possible to state that for the parameter of briquettes quality evaluation the rupture force can be recommended.

Machining has long been the most used technology in manufacturing processes. On the other hand, new materials are being developed or new ways of preparing them are being developed. One of such materials is High Speed Steel (HSS). The article deals with experimental study of a cutting tool durability prepared via powder and casting metallurgy. Durability of cutting tips produced from HSS Vanadis 30 (SN 41 9830) were tested during the short-term radial tests. Three modifications of the HSS steel were studied, while two types of them were prepared via powder metallurgy and the third one was made via casting metallurgy. The measured values were statistically processed and submitted to the remoteness testing according to Grubbs. The results have shown that the most appropriate material for production of cutting tips, ranked based on three studied steels from the durability point of view, appears Vanadis 30 produced via powder metallurgy alloyed by component Nb.

Several models of FDM machines, characterized by different architecture and hardware components, have flooded the market in the last 5 years. As a result, given the high sensitivity of FDM to the specific machine characteristics, the search for optimal printing parameters is a renown problem. This two-parts paper proposes an easy-to-follow and low-cost procedure for the characterization of any given FDM machine. The method allows the evaluation of the effects of a wide selection of FDM process parameters on the quality of 3D printed parts. The first part focused on the definition of a series of metrics to be measured on a series of test prints to evaluate the quality of the produced parts. The evaluation of seven quality parameters on a single print is made possible thanks to: i) a specifically designed specimen that is made available to the user and ii) a rigorous and repeatable measurement procedure, which are both discussed in the first part of the paper. This second part presents the characterization procedure, the statistical tools used in the experimentation (DOE tools and principles are adopted throughout the experimentation) and provides guidelines to be used for the characterization of any FDM machine. The whole procedure is tested on a desktop FDM machine to demonstrate obtainable results, proving the efficacy of the proposed methodology and highlight strengths and drawbacks of the approach.

Nowadays, 3D printing of metallic materials is a hot topic in many industrial spheres as it provides a one-step production of very complex parts. The additive principle based on processing of powders or wires in many successive layers minimizes material losses and so production costs. It also ensures great control over built shapes exactly according to computer-designed models. The most available technology is Selective Laser Melting (SLM) that uses a laser beam to selectively melt a metallic powder into the form of a desired product. The Electron Beam Melting (EBM) technology, that is based on a similar principle, is not so widespread, especially in the Czech Republic. Instead of a laser beam, it uses an electron beam. Related to that, EBM is far more energy-efficient and has different process characteristics. In this contribution, on the example of titanium alloy, we show marginal possibilities of this technology in the processing of bulk materials, from porous to highly dense.

Fractography is the study of the fracture surface and is concerned with the quantitative and qualitative evaluation of fracture surfaces [1]. It is based on the knowledge of the relationships governing the formation and propagation of fracture areas and is routinely used to determine the cause of failure of forensic engineering or failure analysis [2]. A large majority of casting defects can be detected in the fracture surface. In the technical practice, the formation of a fracture surface represents in most cases the unacceptable stage of mechanical loading or other damage, for instance corrosion damage, of material [3]. Fracture interpretation is a function of the fracture surface condition. The fracture surface contains a wealth of information and it is important to understand them [3] - [9]. Energy-dispersive X-ray spectroscopy (EDS, EDX, or XEDS), is an analytical technique used for the chemical analysis (characterization) of a sample. Accuracy of EDS spectrum can be affected by various factors. The likelihood of an X-ray escaping the specimen, and thus being available to detect and measure depends on the energy of the x-ray and the amount and density of material it has to pass through. This can result in reduce accuracy in inhomogeneous and rough samples. The present paper is focused on the possibility fractography to control quality of the castings made of aluminium AlSi7Mg0.3 Alloy to take chance of the tensile test samples.

The Cold-Box Amine method was developed in 1965 by Ashland. For more than 35 years, this method has been applied worldwide and has become the most important method of cold curing. The veining is characteristic defect of cast iron alloys, which accompanies the use of Cold Box-amine cores, the solution to this defect is the content of this paper. There are many factors that affect the surface of the casting and thus the formation of veining. In recent years, products have appeared on the market - additives to prevent veining. Castings using these products should have a smooth surface, no protrusions and other foundry defects. These products have their irreplaceable place on the foundry market, as it is often necessary to eliminate the castings that cannot be cleaned and therefore the veining cannot be removed on these castings. They are predominantly castings for the automotive industry, castings for the railway industry and, in the case of low-quality casting in these sectors, we can talk about gambling with human life. Therefore, it is necessary to pay attention to the occurrence of leaks on castings and to eliminate them with the use of the above-mentioned additives, but we must not forget about many other factors that support the creation of this foundry defect. The paper is devoted to the factors influencing the casting surface and, last but not least, to the used additives in foundries.

The article deals with the monitoring of wear of truck oils in order to determine their wear. The research part is focused on engine oils, tribology and analytical methods for evaluation of oil degradation by abrasion particles. Thanks to these non-invasive technologies for monitoring and analyzing engine wear trends, an optimum oil change interval can be effectively set. The experiment analyzes engine oil samples from trucks and found the values of metal particles. Reference values for oil degradation levels are determined based on trend analysis. Metal abrasion particles and total impurities are determined and the state of the oils is evaluated experimentally.
Optimal oil exchange iterval must be adjusted based on experiments. Wear of the truck engines is very individual with respect to the service life of the oil. The shortening of the interval is suggested with respect to the evaluation of the experiment. The aim of the article is to minimize the negative effects of abrasion during truck operation.