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In the whole world, the economic loss caused by hull corrosion is enormous. Ship painting has become an important part of ship manufacturing process because it can effectively alleviate the corrosion of ship. The manual painting has disadvantages both in the quality and the efficiency. However, the research of automatic sprayers for a ship hull is not widely used because of the complex environment in the shipyard dock and the huge differences in both size and shape of ships to be repaired. Therefore, this paper pro-posed a new method: according to the ship size and blocks distribution in the blocks’ layout of ship yards, the grid method was used to generate the map model; to solve the problems of high rerouting rate, low coverage and large consumption of calculation in the global path planning, a regional division method was proposed to divide the whole area; to shorten the dock occupancy time, a path planning algorithm based on multi robots heuristic cooperation was proposed. Simulation results and experi-mental data show that the full coverage path planning algorithm proposed in this paper has satisfactory adaptability.

Abstract: The article describes a new technical solution for ensuring efficient and inexpensive cleaning, disinfection and sterilization of production facilities and their equipment, based on the principle of gen-erating the use of ozone gas. It describes the technical solution and construction of sterilization and cleaning equipment with ozone gas and the sterilization of small objects, especially textiles contaminat-ed with various viruses, including the Covid-19 virus. The device is designed as energy-saving, structur-ally simple, with high sterilization and cleaning efficiency. The sterilization device is small in size, mo-bile and its design enables transportation in the trunk of an ordinary passenger car. The weight of the device is 14 kg. The device's ozone source is an ozone air purifier, mass-produced according to valid EU standards. The power source of the ozone purifier is an electrical source with a voltage of only 230 V and a frequency of 50 Hz. Alternatively, it is possible to use power from a safe mobile source or inverter. The operation of sterilization and cleaning device in a closed, non-ventilated area, does not endanger peo-ple's health or damage plants. The description of the construction of a technical sterilization device is focused on a specific type of device, but the stated theoretical results can be equally well used in the electrotechnical, food, medical or pharmaceutical industries and in general wherever there is a need to effectively and efficiently clean and sterilize production objects, their equipment, used materials and all other production aids means and tools.

At present, electromagnetic induction quenching and nitriding are two commonly used surface strengthening approaches applied in improving the strength of the steel parts. In this paper, a comparative study was proposed to research the strengthening effect of these two technologies in improving the fatigue strength of steel crankshaft. First a modified statistical analysis approach of the fatigue limit load was proposed to obtain the distribution of the fatigue limit load. Then two types of steel crankshafts were selected to be the object of research and treated by these two techniques. Finally the standard T and F hypothesis testing methods were conducted in evaluation the strengthening effect. The results showed that compared with the nitriding approach, the electromagnetic induction approach can improve the fatigue strength of the steel crankshaft more obviously, thus is more suitable for engineering applications.

This study focuses on performing the analysis of manipulator operations on the machining line of precision mechanical products using the Human-Machine correlation analysis tool through images collected from the camera, wasteful operations incurred in machining according to Lean Six Sigma (LSS) standards to control fluctuations in the machining line, improving the overall productivity of the line (OEE). Specifically, contributing to improving productivity, quality, and competitiveness of the company in the market, create a good product image for consumers. This paper proposes a 7-step quality control (QC) cycle improvement model, called 10 step QC cycle. In step 5, use Man - Machine correlation analysis tool from video images to identify wasteful activities. In step 6, we propose a Direct Numerical Control (DNC) model to call the machining program for MC machines using a barcode system and a computer vision model for human identification at each processing line according to a controlled fixed layout. The right people have been trained enough to operate the line; the specific result is eliminating the occurrence of accidents in processing from 7 cases to none. A model of a product dimensioning system implemented for fully automated product quality control combined with redesigned machining jig with a vapor sensor system eliminating the reliance on human manipulation Specifically, the result from this improvement activity is the increase in productivity from 115 products per 8 hours to 155 products per 8 hours and the handling time has decreased from 1.3 hours per day to 0.36 hours per day (reduce 0.94 hours per day). The Partial Least Squares Structural Equation Modeling (PLS-SEM) is used to analyze the results of the survey of employees' opinions about the usefulness, convenience, and technical factors after the operation. The results from improvement activities show that user loyalty is highly appreciated in terms of usefulness and convenience. However, in terms of technical factors, it is still necessary to improve the quality of the information network system, the barcode scanning system and the quality of barcodes in the oil environment

The main aim of this case study is to present the changes caused by heat treatment on the structure and properties of 100Cr6 steel by annealing, hardening, and tempering in combination with previous chemical-heat treatment (CHT) by boriding. The boriding causes changes to the microstructure of the steel samples, which include a change in the morphology of the deposited cementite and a change in the volume of the chromium carbide particles. The cementite is transformed from its original granular form to a lamellar form. An increase in the proportion of chromium carbide particles in the sample occurs due to the higher affinity of chromium for carbon. This leads to precipitation of chromium carbides rather than carbides of iron. A multi-phase diffusion layer Fe2B-FeB with a thickness of 31 ± 2.8 µm is formed during boriding, with a typical tooth-like texture. Although the diffusion layer does not have the same toughness and resistance as the single-phase Fe2B diffusion layer, samples after boriding increase their resistance to tribological abrasion by 29 % compared to samples without this treatment. After quenching and tempering of the borided samples, a maximum tensile strength of Rm = 1779 MPa is measured. Compared to samples which are only quenched and subsequently tempered, this is an increase in tensile strength of about 59 %.

The paper presents the results of experimental work on the assessment of 3D geometry of surface stereometry obtained as a result of Water Jet (AWJ) water-abrasive beam cutting using an Eckert Opal WaterJet COMBO hydro-abrasive cutter. Studies of geometric structures were conducted using the Alicona Infinite Focus microscope. The article analyses selected spatial roughness parameters of the multilayer structure surfaces combined as a result of the vulcanization process with an aluminium alloy surface. The results of the research work are summarized in the technological function of the WJ cutting conditions, such as the cutting speed and the mass flow of the abrasive material.

Technological progress in the 21st century has catalysed the industrial revolution (Industry 4.0) following the development of multiple new industrial automation technologies in the manufacturing sector. Regardless, past research indicated the unsuccessful attempts in adopting Industry 4.0 technologies among manufacturing organisations. Undoubtedly, the operationalisation of Industry 4.0 in manufacturing proved challenging as organisations were required to evaluate various aspects for effective implementation. Thus, a sound understanding of constructs concerning employees’ acceptance and readiness levels towards novel automation technologies was required. Hence, this study aims to explore, develop, and validate the suggested conceptual framework by integrating the Technology Acceptance Model (TAM) and Technology Readiness Index (TRI) with Exploratory Factor Analysis (EFA). The EFA process was the first crucial step in ensuring the internal consistency and stability of the instrument across the sampling population. Consequently, the research outcome potentially enabled the manufacturing sector to identify and comprehend the key determinants in designing industrial automation technologies. This study also contributed to knowledge on technology acceptance by synthesizing TAM 3 and TRI 2.0 theories, thus constructing a new TAM in manufacturing.

Leading manufacturers and sellers of products in the field of rolling bearings for the automotive in-dustry guarantee their quality. Extensive product testing is required to guarantee quality. When test-ing wheel bearings, bending fatigue test stations are used, among other things, to verify the strength of components. The content of the presented work is the analysis of the effect of bending moment on the temperature of a newly wound wheel bearing of the 3rd generation, based on experimental measurements. These are dynamic tests of the strength of wheel bearing components at a resonant test station. This verification is very important and has the effect of preventing the start of mass pro-duction of components that do not meet the basic safety requirements.

The aim of the article is to analyze the friction welding process of steel pistons, due to the small amount of scientific literature on this subject. First, it is necessary to present the design fea-tures of steel pistons and their advantages and disadvantages. Then analyze the types of friction weld-ing processes used in the production of pistons of internal combustion engines with the analysis of their differences. Present two basic methods of welding in the production of steel pistons, i.e. friction butt welding and low pressure friction welding. Finally, a proper analysis of the friction welding pro-cesses of steel pistons of internal combustion engines can be presented. At the end, the conclusions of the analysis are presented and proposals for improving the process are made.

The article deals with a possibilities of an enhancement of functional properties of highly stressed components by specific combination of surface technology. Two surface technologies such as plasma nitriding and laser shock peening were selected for the experiment. Those technologies were applied upon steel 42CrMo4 frequently utilized in manufacturing of strained components. Properties obtained by applied surface technologies were tested by following experimental methods. The chemical composition was verified by optical emission spectrometer Tasman Q4 Bruker. The surface morphology was inspected by scanning electron microscope TESCAN MIRA 4. The microstructure of heat treated as well as of nitrided specimens was observed by opto-digital microscope Olympus DSX500i. The microhardness profiles were measured by microhardness tester LM247 AT LECO. The friction coefficient was tested on tribometer Bruker UMT 3 TriboLab. For an assessment of the surface wear resistance the profilometer Talysurf CLI 1000 and Contour GT were utilized. The experimental results show that although the proposed surface technology combination manifests itself to be disadvantageous, both technology LSP, as well as plasma nitriding, applied separately, can lead to a significant wear reduction.

The continuous development of construction due to the great needs of society and industry, the need to build newer and more durable buildings have meant that scientists all the time look for new opportunities to improve the quality of materials used in this field. Above all, concrete, as material commonly used in construction, has been the subject of research for many years in order to improve the properties. Already in antiquity there were the first attempts to modify the building material with fibers. Initially, they were organic fibers. However, the first patent dates from 1874, when A. Bernard patented the idea of strengthening concrete with steel filings [1]. Then, attempts were made to strengthen the concrete with long steel fibers, which was done by H. Alfsen in 1918. Further researches led N. Zitkiewic to test the strength and impact toughness of concrete with the use of pieces of mild steel wire [2]. Steel fibers in concrete were used for the first time by Romuladi and Baston in 1963. In the paper a comparative analysis of selected mechanical properties for concrete and fiber-reinforced concrete, e.g. compressive strength and Young's modulus, was presented. It was checked how the value of Young's modulus and the compressive strength of concrete change depending on the content of steel fibers. Three types of samples were tested: 1 - concrete, 2 – fiber-reinforced concrete containing 0.25% of steel fibers, 3 – fiber-reinforced concrete containing 0.50% of steel fibers. As the analysis has shown, the greater number of steel fibers is not directly proportional to the increase in its compressive strength or the value of Young's modulus.

The article deals with new types of coatings and their mechanical properties. CTRN and CRONAL are newly developed coatings intended for active parts of forming tools. Their behavior and mechanical properties are still under investigation. Coatings are used for functional components in various areas of industries, their de-velopment is constantly in process. The aim of the study and the experimental solution provides a compari-son of the mechanical properties of the new coatings with the well-known coatings DLC, TiN and TiSiN. The aim of the work was to perform an analysis of CTRN and CRONAL coatings and compare their me-chanical properties with other coatings. We chose the methods of nanoindentation, hardness measurement, scratch test and layer roughness. The results will allow easy determination of the proper coating for a suitable material. The results present the specific functionality of the individual coatings.

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.

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 firefighting ladders belong to essential tools used by members of the Fire Rescue Service of the Czech Republic. In the past, wooden ladders were used although their applicability and duration were strongly limited. Formerly used wooden ladders were then replaced with steel-made. However, the weight of such ladders caused big problems during the firefighting and therefore an aluminium ladders made of AA 6063 alloy are nowadays used. The ladders are however susceptible to thermal effects during firefighting and may reduce its mechanical properties. The present paper reports the microstructural change of two different ladders both made of AA 6063 alloy when annealed at different temperatures and duration. Both the ladders showed almost similar behaviour reaching the highest decrease in theirs TYS and UTS when exposed to a temperature of 400 °C reducing its initial TYS of 229 MPa for ladder no.1 and 237 MPa for ladder no.2 down to 71 MPa and 81 MPa, respectively.

Within the context and term of quality it can be comprehended as a subjective character. Every individual has its own requirements, expectations or standards on specific product or service. Thus, these parameters are then connected and defined by different priorities. Many of the customers are willing to pay more money for increased quality of bought product however many of them are forced to decrease their requirements due to the costs and they have to be satisfied by products with lower quality or lesser amount of defined parameters. The main aim of the paper is to observe and analysis of cost system and its effect on product quality through the monitoring, analysis and evaluation of production costs in selected organization. Due to the comprehensive evaluation of the effects of investments on the resulting quality in selected organization a various methods was employed. Among used methods was comparison of investments into production quality by data analysis according to PAF model, mathematics and statistical parameters and Pareto's analysis. There were suggested individual steps by utilization which allows determining, evaluating and creating an individual system of observation and evaluation. Such a system of costs analysis is then suitable for selected companybut not limited to it. The utilization of such a system is therefore applicable at any company or organization which is focused on custom small-series production.

Currently, it is in the power industry exerted the pressure in terms of environmental impact and economics. That means requirements focussed on the development of high efficiency and low emission systems. Both of these requirements leads to the increasing of the thermal efficiency of a power plant and that means also increasing of the working temperatures. In the future, it will be necessary to develop materials that can withstand these demanding conditions and requirements. Strength of steel used at high temperatures is one of the properties which affect the life time of the power equipment. These properties strongly depend on microstructure of material. However, useful initial microstructures are unstable in service conditions. The changes come gradually at temperature-dependent rate through processes of thermal degradation. Many of these processes are caused by changes in the carbide structure of the steels and other phase transformations.This contribution deals with the degradation structures of the steels applied in energetics.

This work deals with the construction of a steel hangar with a sheet metal shell for storage sports flying equip-ment (SPE) or general aviation aircraft. The design of the building was made to ensure an individual approach to each aircraft. The construction was designed with price and safety in mind. An available option is an electronic security system connected to the central security desk via the Internet, mobile phone or other data transmission.

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

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

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

There are a number of methods for measuring propeller pitch but it could be a problem for many fishing boat builders who lack of professional equipment. This paper presents a method of propeller pitch measuring based on photogrammetry and CAD (Computer Aided Design). This method con-sists of three stages. At first, a series of photos of the propeller were taken by a smart phone. After that, these 2D images were processed by a photogrammetry software to create the 3D virtual model of the propeller. Finally, in CAD environment, the pitch at different radii of each blade of the 3D vir-tual model were measured. To validate the proposed method, several propellers for fishing boats were measured and the measuring results were compared to those archived by using an EDM (Electrical Discharge Machining) machine and by a highly skilled man with simple tools. The measurement results show that the proposed method could be acceptable for measuring pitches of propellers of fishing boats.

Vehicle Routing Problem is a common problem in logistics, which can simulate in-plant and out-plant material handling. In the article, we demonstrate a Vehicle Routing Problem, which contains period, time window and multiple depots. In this case, customers must be served from several depots. The position of the nodes (depots and customers), the demand and time window of the customers are known in advance. The number and capacity constraint of vehicles are predefined. The vehicles leave from one depot, visit some customers and then return to the depot. The above-described vehicle routing is solved with construction algorithms and Ant Colony algorithms. The Ant Colony algorithms are used to improve random solutions and solutions generated with construction algorithms. According to the test results the Elitist Strategy Ant System and the Rank-Based Version of Ant System algorithms gave the best solutions.

Two extendable firefighter ladders, both made of AA 6063 alloy, has been destructively tested accord-ingly to the ČSN EN ISO 1147 to determine the maximal load before their failure. For this purpose, two brand new ladders with a complex profile were compared to the 5-year old one with a far simpler profile. It was found, that the new ladder broke already at a load of 366 (365 kg) while the 5-year old ladder could withstand a much higher load of 426 kg. Since both the ladders broke nearby the guides acting as a mechanical support for their extension, it was of high interest to investigate the cause of different behaviour. Considering the fact, that the brand new ladder had a much more complex pro-file of the beam and the fact, that the guides were welded to the beams, it was of high importance to investigate the influence of the weld on the overall integrity of the ladder. It was found, that the weld itself deteriorated the mechanical properties of the beam reaching the minimal hardness in the dis-tance of 10 mm, which also corresponded with the crack initiation site. This place also showed the lowest hardness reaching only 52 HV 1.

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

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

The production of automotive products from polymeric materials represents operations associated with the flow of material during its shaping to the desired final mold. The technological aspects of the processing of polymeric materials are closely related to the rheological properties. The article deals with adding technological waste from production to virgin material and its influence on rheological or flow properties of selected polymer composite. The analyzed material is used in the manufacture of components (connectors) in the automotive industry. The rheological properties were measured in two stages. In the first stage, rheological properties were assessed in the short term immediately after preparation of the test samples. In the second stage, half of the samples were exposed to elevated temperature and the effect of aging on the rheological properties of the material was monitored. Based on measured MVR values before exposure to elevated temperature, it can be said that the amount of process waste does not significantly affect the flow properties of the polymer. After exposure to elevated temperature, there is a significant decrease in polymer flow properties probably due to the crystallization of the macromolecular chain.

A number of asset management models, methodologies and tools are available and well known today. How-ever, various organizational approaches to asset management processes are adopted by companies in the industry. In the paper, a number of examples of maintenance process models are summarized and a comparison of examples (benchmark) of real maintenance organizational structures is presented. The used examples origin from chemical, petrochemical and automotive industries. On this background, a case study of major maintenance organization change in Unipetrol, a central European refinery and petrochemical group (part of PKN Orlen) is presented and analysed. The goal of the implemented changes in the company was to increase the overall efficiency of the maintenance organization, mainly in the areas of management, and to achieve the set KPIs. Organizational changes were implemented on the basis of a model of a close connection between maintenance and production organizations in the form of a Multi-profession production team, named “Facility team”. The changes in the organisational structure and asset management processes described in the paper had finally a significant impact on the number of management positions (reduction by 25%), roles, competencies and asset management process flow. The quantitative impacts to KPIs in areas fulfilment of process safety requirements and efficiency, after implementation this changes, it had a positive effect in the horizon of the coming year and are also evaluated and analyzed in the paper.

In the present study, local defects in deep groove ball bearings are studied as forward and inverse problems. To this end, the separation-integration method is applied for modeling the forward problem. It is assumed that the inner race of the rolling element is multi-DOF, while the outer race is deformable along the radial direction. Then the problem is modeled with concepts of the finite element method. The contact force for the rolling elements is described by the nonlinear Hertz contact deformation. Various surface defects originating from local deformations are introduced into the developed model. Since the outer ring can be coupled with the FE model of the housing, the developed bearing model is capable of considering the transmission path of the bearing housing. Then model parameters are modified to reach better performance in predicting local defects. Through translating the inverse problem into the comparison of the geometric distance, measured indicators are used in the defect detection process and the relative location and size of defects are predicted. Finally, the defect range is established to evaluate the fault severity. Obtained results demonstrate that the proposed method is effective and accurate in the studied cases.

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