December 2019
In the process of die casting the final quality of a cast is influenced by a great number of factors. The interpretation of the impact of the individual factors of die casting is based on the concept of the filling of a mould cavity. The issue of the filling of a die casting mould is complex due to the fact that the factors such as the cast structure and the mould thermal balance usually determine the r (…)
This article deals with a designing of one part of a smart factory model with the Industry 4.0 principles. It is a three-axis CNC milling machine with automated changes of tools and workpieces. The emerging factory is not controlled centrally, but each facility has its own control system and communicates with other facilities via IoT – Internet of Things principle. The machine tool is designed to mach (…)
This article deals with the new method for producing solid lubricating coatings on steel tools by thermo-hydrochemical treatment (THCT). The results of investigation of tribological properties of the coatings fabricated on high carbon steel of У8 grade (0,8 wt.%С) using THCT method are presented. The composition of the medium and the temperature and the time parameters of THCT process were optimized by (…)
The paper deals with a study of buckling behaviour of a bar, which is fed into the drawing tool in the production of drawn bar. When the undrawn bar is inserting into the two-die drawing tool by using hydraulic feeding collets, it can be buckled and stuffed between dies. Accordingly, basic parameters, such as a maximum possible buckling length, have to be found. Due to a specific shape of the drawn bar (…)
Five-axis finish milling is a complex process. The requested surface quality and accuracy must be produced in the shortest possible time. The three main process characteristics - quality, accuracy and machining time - are closely related one to each other. They are affected by the dynamic properties of the machine tool structure, the feed drive properties including cascade control, the control system in (…)
The main objective of this paper is to establish models of measured real-time data that are obtained in a frontal impact of a vehicle into the rigid barrier. When it tcomes to modeling the vehicle crash we can distinguish two approaches. The first one utilizes CAE (Computer Aided Engineering) software including FEA (Finite Element Analysis) while the second one is based on the System Identification To (…)
There are increased demands for safe, reliable and economically efficient operation of modern technical devices nowadays. These technical devices need an appropriate monitoring system in order to fulfil all the requirements. This consequently monitors their activity while providing appropriate information on operating parameters. As a result of them, the control system of a technical device can perform (…)
The article presents a promising non-contact face seal of the rotor of a dynamic machine. The principle of pulse balancing of the movable sealing ring is applied in the seal design. The design of the test equipment and seal samples, which were used to conduct comprehensive investigations of the seal in the operating range of speeds and pressures, are considerated. The analysis of the experimentally obta (…)
The results of theoretical and experimental studies of tribotechnical purposes composites on the basis of polytetrafluoroethylene (PTFE) and epoxy composite material with fillers of different chemical nature are given. The results have been obtained that prove that the introduction of carbon fiber of optimum length ensures the formation of a composite structure in which the fibers are evenly distributed (…)
The paper discusses a self-organization phenomenon, physical and chemical aspects of friction, and the methods of friction control using advanced polymer composites based on polytetrafluoroethylene (PTFE). The article also concerns a generic physical and an engineering approach to the development of new wear-resistant polymer composites with modified fibers filler. The influence of the mechanochemica (…)
At first two-layer, HA-ZnO/Alg coating was obtained on the pre-anodized Ti6Al4V substrates by the thermal substrate deposition method (TSD). In the frame of this work, TSD method was at first applied for obtaining ZnO coating from aqueous alginate-containing solutions on a pre-deposited OH layer. XRD, SEM analyzes show that the biopolymer has a significant influence on the coatings formation, their mor (…)
Achievement of desired service life, of correct and reliable function as well as meeting demands regarding replacement of engineering products requires observance of exact dimensions of functional areas as well as accuracy of geometrical shape, direction, reciprocal position of areas and of other elements of components. Tolerance of shape, of direction, of position and of flapping is commonly referred t (…)
Electrical Discharge Machining (EDM) is one of progressively developing machining technology. Its advantage over other progressive machining technologies is the high achieved accuracy of the machined surface. Moreover, in this case, it is machining without force, which means that the mechanical properties of the material to be machined do not impose almost any limits. However, during EDM, the material i (…)
The material of blanking tool was identified as one of the negative factors affecting high non-conformance and downtime in the blanking process. The aim of this paper was to choose a suitable alternative to the original material of blanking tool for achieving a longer operating tool life, and thus enhance the effectiveness and efficiency of the blanking process. Recommended materials by supplier were Ca (…)
The paper is focused on qualitative and quantitative evaluation of the thermal properties and thermal bridges of the old poultry structures. The results of the paper claim poor thermal properties most of the constructions. Qualitative detection of thermal defects with the utilization of infrared thermography claimed the most significant thermal bridges on uninsulated socle and flooring, straining band o (…)
The aim of the paper is to point out to a possibility of program creation which would facilitate calculation of geometric dimensions of worm gearing system for students at secondary technical schools and universities as well as for employees working in the technical field with the following parameters: module, number of worm teeth, gear ratio, and coefficient of worm diameter. The paper contains a detai (…)
The paper describes created applications for matching the dimensions of tight keys to shafts and design proposal of a slot for tight keys in the shaft and in the hub. The designed application determines basic dimensions in dependence on shaft diameter: breadth, height of the key and specifies the depth of the slot in the shaft and in the hub with corresponding marginal deviations of dimensions. The appl (…)
The presented paper deals with the design proposal and application of the program for calculation and check of chain gears. The computing program has been created as a spreadsheet in the working environment of the Microsoft Office program by the Excel application through defined sequences of the individual commands. The program serves for the design proposal of a chain drive by means of inserted databas (…)
Noise is pervasive in everyday life and can cause two kinds of health effects - auditory and non-auditory health effects. The most investigated non-auditory health endpoints for noise exposure are perceived disturbance and annoyance, cognitive impairment (mainly in children), sleep disturbance, and cardiovascular health. The article presents a case study of non- auditory effects of noise on humans. This (…)
During the damage evolution of bonded joints, different modes of failure can be detected. These modes include pure modes (Mode I, Mode II, Mode III) or their combinations (Mixed-mode) according to the type and the direction of loading. Some scientifically validated test methods are commonly used to obtain the fracture toughness by loading under pure Mode I, Mode II and their Mixed-mode. Some test method (…)
An overview of the Extreme Ultraviolet (EUV) source to be constructed in the frame of the Czech national R&D project HiLASE (High average power pulsed LASErs) is presented. The HiLASE EUV source will be devoted to industrial and medical applications, as well as to fundamental studies (such as the chemistry of polymers). This wide variety of different applications depends on the possibility of targeting (…)
Measurements of solid aerosol concentrations are important tools to monitor air conditions at the workplace. In particular, the requirement for the workplace air quality management is necessary to prevent health damage and occupational diseases in exposed jobs. In this case, exceeded limit values for the concentration of solid aerosols were measured for all exposed workers. If such concentrations persis (…)
The article is focused on the description of problems that can be caused by increased temperature of drinking water in public drinking water distribution system (DWDS). Increased water temperature is an actual issue that the water industry has had to address in recent years, particularly as a result of the ongoing climate change. In recent years, long periods with high air temperatures have been more fr (…)
Reaching a consensus in strategic and key decision processes always have been a big challenge in top management in enterprises globally, as they are required to make decisions much more accurate and quicker due to the increasing amount of inputs in the current reality of Industry 4.0. This article presents a case study of a multi-criteria group decision making (MCGDM) model for the supplier selection of (…)
The article describes an introduction to the problem of drainage of flat roofs, namely by using a vacuum drainage system. The article describes the current state, which also describes the gravity drainage system, whose design is in partial "retreat", unless required by local conditions or the investor of the construction. The following describes the advantages and disadvantages of the vacuum system and (…)
Sanding with handheld powered tools has been recognized as one of the most significant factor in personal exposure to wood dust in the woodworking industry. The aim of this study was to investigate the effects of wood species and grain size of abrasive on wood removal and mass concentration of wood dust emitted by a random orbit sander. Experimental study was designed as 4x4 full factorial experiments. (…)
The presented paper contributes to solution of safety assurance in complex mechatronic systems used in theatre stage technology. The aim is to solve the problem associated with reasonably foreseeable incorrect behaviour of persons and operators of these systems by application of safety measures respecting the nature of the specific conditions in which such mechanisms are being used. Special attention is (…)
This paper deals with the thermoelastic response of ferrous and non-ferrous metals at different loading rates. The goal is to predict the stress-strain response based on temperature changes caused by adiabatic processes. These data are intended to be used for non-destructive full-field thermal stress analysis (TSA). The influence of strain rate on temperature was investigated in cyclically loaded dog (…)
More powerful and challenging laser systems are built to meet the need of evolving technology, reflecting demands coming from both industry and research areas. Laser damage is a key parameter for all components in such high-power laser system, establishing limits of maximum achievable energy in laser beam, and consequently the power of the system. As a value for all optical components, this is represent (…)
Nanostructuring and microstructuring approaches frequently used in microelectronics manufacturing, such as electron beam lithography or nanoimprint lithography, are considerably slow. In order to reduce processing time, laser patterning methods based on interference of multiple beams have been developed. Within one laser pulse, a significant part of an irradiated area on a sample surface is patterned wi (…)
Growing demand for superhydrophobic surfaces in recent years is associated to many attractive science and engineering applications including self-cleaning, anti-icing and anti-corrosive behaviours. Stainless steel type AISI 316L is one of the most versatile and widely used engineering material in industries. Inspired by the “lotus effect” nano/microstructures has been fabricated by direct laser writing (…)
The HiLASE Centre is equipped with a Laser Shock Peening station (LSP). LSP is a surface enhancing technique and it is used to prolong the fatigue life of metallic components. Part of the station is a FANUC M-20iA/20M 6-axis industrial robotic arm equipped with an R-30iB controller. The robotic arm is used to handle the LSP samples In order to facilitate the utilisation of the LSP station at the HiLASE (…)
Laser Shock Peening (LSP) is a process where high energy nanosecond laser pulses are used to modify surface characteristics of treated materials. In this work, the LSP process is briefly explained and its effects on roughness, hardness and residual stresses of aluminium alloy 5083 are demonstrated. The LSP process is based on small plastic deformation caused by laser impacts on the surface which natural (…)
The Jones matrix based polarimetric method suitable for the spatially resolved analysis of the thermally induced birefringence and dichroism in complex high-power laser optical systems is proposed. The measurement allows the characterization of the complete local Jones matrix of the optical components, or their sets. The method of extraction of the particular contributions of the linear and circular bir (…)
In the last two decades, the price of the laser diodes significantly dropped and made them an energy-effective solution for pumping high energy class high average power solid-state lasers. This is a significant advantage for the potential use of such lasers in industry, where operation cost is considered. The efficiency of such diode-pumped lasers is much higher compared to the previous generation of fl (…)
Ultrashort-pulse, high average power thin-disk lasers matured and became efficient tools for precise material processing and hi-tech laser applications. Hilase centre developed a diode-pumped thin-disk laser platform for Yb:YAG regenerative amplifiers delivering pulse energy >40 mJ, pulse repetition rate up to 400 kHz, nearly diffraction-limited output beam, and average power reaching of >500 W. The pla (…)
Kerr lens mode locking (KLM) is an efficient way, how to generate ultrashort laser pulses. Employment of the KLM in thin disk-based lasers allows for generation of high average power ultrashort pulses reaching megawatts of peak power without adoption of the chirped pulse amplification technique. We demonstrate a small KLM Yb:YAG thin disk laser generating 240 fs long pulses close to 21 MHz repetition ra (…)
Increase in energy of ultrashort (picosecond, femtosecond) laser pulses is typically based on chirped pulse amplification (CPA) method. The nanojoule energy pulses are temporally stretched by several orders of magnitude prior amplification. The peak power is significantly decreased and the gain saturation and detrimental nonlinear optical effects, leading to the beam degradation, are avoided. Amplified (…)
A single-mode ytterbium-doped continuous-wave fiber laser operated at a wavelength of 1030 nm is designed and utilized for frequency doubling at 515 nm in a periodically poled lithium niobate (PPLN) crystal. The standard single-pass of the PPLN results in a conversion efficiency of only 2 % due to the low intensity of the continuous-wave laser even though optimal focusing into the PPLN is used. Because (…)
A Safety Laser Interlock System was required for the Laser Laboratories in the HiLASE Centre in Dolni Brezany. The goal of the work was to develop a universal Laser Interlock System, which would control all the laboratories and the interlocks of multiple lasers with different powers and wavelengths in the laser laboratories in compliance with ISO EN 13849-1, Safety Performance Level PLe. The Safety Cont (…)
Laser beam distribution requires complex opto-mechanical system allowing safe and precise delivery of different laser beams from hall laboratories to experimental workstations developed within the HiLASE project of the IOP in the Czech Republic. The unique nature of new generation of HiLASE high energy diode-pumped solid state laser systems with high repetition rates requires advanced design approach. W (…)
Silicon is one of the most used materials in nanostructure research and in a wide range of high-technological applications spanning from the fine chemical industry to medicine and to semiconductor electronics. The processes underlying laser-induced nanostructuring of Si surfaces are still not fully understood. In particular, it is not completely clear how individual surface defects contribute to generat (…)
Modification of thin metallic films using ultrashort laser pulses involves interplay of numerous physical processes. Finding a right combination of laser parameters is essential for achieving the desired modification of a thin film deposited on a substrate. Numerical modeling is a convenient tool for gaining insights into ultrafast evolution of material properties and to predict an optimal range of irra (…)
Spot size measurements of a 260 fs, 1030 nm focused spatially Gaussian pulsed laser beam were performed on a Silicon surface with native and thermally grown SiO2 layers using a widely known method of evaluating laser beam energy dependent damage area. Single pulse laser induced damage thresholds of both samples were also measured. Modification of the thermally grown SiO2 layer was analyzed in detail us (…)
Silicon nanostructures can be prepared by different methods that considerably change their optical properties depending on experimental conditions. They are also very sensitive to molecular environment and external influences that can be used for multiple applications in different areas. Silicon nanostructures prepared by laser ablation show large perspectives for molecular sensing and biomedical applic (…)
The optical response of metal surfaces to high-power laser excitation (HPLE) is one of important topics of laser-matter interaction, which remains to be poorly understood. It is known that certain metals, which are well reflective at normal conditions, become considerably absorbing during irradiation by ultrashort high-power lasers. Reflectivity of such metals during the irradiation stage is a key param (…)
The numerical model presented in this article describes the heating of a thin strip of amorphous silicon on glass substrate by a continuous-wave Ar+ laser. The heat flow equation is solved using a finite difference method based on the implicit scheme with splitting by coordinates. A short overview of the methods of numerical analysis is given and the finite difference method is described in details incl (…)
Natural gas is one of the cleanest organic fuels, nevertheless, it produces pollutants in the combustion process. The major pollutants of the combustion in the atmosphere are carbon monoxide CO, nitrogen oxides NO, NO2, sulphur dioxide SO2 and hydrocarbons. The current article deals with the problematic of the high NOx formation rates under the high power operation. The object under research was a middl (…)
The purpose of hardening is the increase the hardness of the steel by creating an imbalanced structure. High hardness can be achieved by the formation of a martensitic structure. In some specific cases, we try to obtain a bainitic structure when hardening. In real hardening processes, a martensitic structure is usually achieved on the surface of the body, producing a mixture of martensite, bainite and o (…)
The article deals with suitability assessment of selected types of materials needed for the manufacture of plastic holder of parking sensor, which is located in the vehicle bumper. By applying the PTC Creo Mold Analysis simulation tool, the manufacturing process has been assessed to minimize potential errors affecting not only the appearance properties of the final part, but also its mechanical properti (…)
The article contains the results of identification of manipulator arm dynamics that is driven by pneumatic artificial muscles (specifically, fluidic muscles). The NARX architecture model - a multilayer perceptron network (MLP model) was selected for identification. Simulations were realized using MATLAB, especially with use the System Identification Toolbox. The simulation results were tracked at 3 diff (…)
The study of the Digital Factory consists of the design of an automated manufacturing system with elements of autonomy within the concept of Industry 4.0. This study origin was inspired with the production of drumsticks. For the intended purposes, manufacturing system designs for Factories of Future are created. The system consists of elements that are part of the digital production with automated funct (…)
This article deals with a process of designing an inexpensive device for automated scanning of people and large objects. The attention is paid to selection of technical solution of individual system components, from construction to calculation for motors of individual movement axes. The result is a device that allows automated digitization of objects with up to two metres of height, using simple and aff (…)
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