Fulltext search in archive

The presented article focuses on the surface analysis of the components manufactured by different additive technologies and their reverse digitization. Sintered components were manufactured by SLM and ADAM technologies, while their surface was analyzed using a progressive optical measurement method. To examine the possibility of reverse engineering, the components were optically scanned with a laser scanner and compared to their CAD model. Based on empirical experience, to scan opti-cally the metal and lustrous surfaces is a challenge. The components were manufactured from anti-corrosion materials 17-4 PH and 316L–0407.

The paper presents the possibilities of using the wavelet transform to filter the cutting force signal. Tests were carried out by dry turning on the Ti6Al4V alloy with variable cutting parameters. Four blades with different nose geometry and coatings were used. From the recorded waveforms, the mean values of the force component Fc and the load stability coefficient were calculated. The measured force waveforms were filtered with Daubechies 4 (db4) and Daubechies 6 (db6) wavelets. From the ratio of the load stabil-ity after filtration to the load stability before filtration, the noise and disturbance values generated during the turning of the tested alloy and the force measurement were estimated. The conducted research shows how the machining conditions affect the values of force, stability, and thus also the variability of the cutting edge load when turning a titanium alloy. They also show the effectiveness of the Discrete Wave-let Transform (DWT) in separating the noise from the force signal.

The paper deals with the technology of production of deep-drawn plates from alpha brass CuZn30. Surface and hidden defects are often observed in these deep-drawn sheets. The research was aimed at reducing the occurrence of these defects and subsequently reducing scrap and increasing the quality of these metallurgical products with a tighter tolerance of the required structural and mechanical properties throughout the length and width of the sheets. The production technology was monitored from the preparation of the batch and casting parameters on the existing operating equipment, through the processing of the ingots by hot and cold rolling, to the recrystallization annealing of the sheets in coils in a hatch furnace and the subsequent continuous pickling and passivation of the final strips. Properties were monitored after each technological operation of production. Specifically, macrostructure, microstructure, microporosity, tensile mechanical properties, and hardness were analysed. The results showed that the chosen production technology has sufficient homogeneity of properties.

The paper describes the experimental validation of the biomechanical response of the Hybrid III 50th Percentile Male Pedestrian Dummy (JASTI, Tokyo, Japan) at low impact velocity (up to 2.2 m/s) in comparison with that of human probands. The paper is based on previous research that was focused on the tram-pedestrian crash tests using the same dummy. The biofidelity of the dummy was analyzed in two collision scenarios: the anteroposterior impact (chest impact) and lateral impact (shoulder impact) using a unique pendulum impact testing machine of own design and construction. The primary outcome variable was the peak resultant acceleration of the head and chest during the impact. Based on the lab-based measurements, the unique impact testing machine was found adequate and precise for the purposes of future crash-test analyses in the area of the automotive industry. The proposed methodology and measurement protocol were shown proper to compare the data between the dummy and human participants. Following the pilot experiments, the kinematic and dynamic data between the dummy and human participants were analyzed to assess the biofidelity of the dummy for the frontal and side impact during tram-pedestrian collisions at low impact velocities.

This study aimed to investigate the influence of single-wall carbon nanotube (SWCNT) content on the mechanical properties of polyurethane (PU) nanocomposites. The SWCNT content varied from 0 wt% (reference sample) to 2 wt%. Tensile, hardness and Charpy impact tests as well as dynamic me-chanical analysis (DMA) were performed. Based on the test results it was observed that an increase in the content of single-wall carbon nanotubes resulted in significant improvements in material strength and stiffness. Furthermore, atomic force microscopy (AFM) was used to examine microsurface to-pography of the samples and to obtain spectroscopic curves, based on which local elasticity was eval-uated. Overall, performed measurements indicate that the incorporation of SWCNTs into PU matrix makes resultant nanocomposite stiffer and more resistant to deformation. The results highlight the potential of SWCNTs as effective reinforcement of polyurethane-based nanocomposites.

This paper investigates the rubber wood honeycomb core by manipulating its cell wall thickness. Rubber wood honeycomb core was fabricated with cell walls range from 1 mm to 3 mm. The impacts of the cell geometrical parameters on the flexural and out-of-plane compression performance are studied. In the case of solid rubber wood without facesheet, the density is much higher than those rubber wood honeycomb composites. The failure can be disastrous without facesheet under bending. Rubber wood honeycomb sandwiches are able to offer the similar specific flexural strength with lower density. With increasing wall thickness from 1 mm to 3 mm, the specific flexural strength increased by 12.32 %. Meanwhile, specific compressive strength improved by 11 % from 1 mm to 2 mm. However, its specific strength dropped by 3.55 % when the wall thickness at 3 mm. Minimum improvement in the compressive strength per density has caused the decrement.

Fused Filament Fabrication (FFF) printers are usually designed to create a product with one single ma-terial. Some of them allow fabricate items in multiple colours but creating a single product consisting of two different materials remains an advantage of industrial 3D printers only. The aim of this research was to develop a design of a device with two printheads which enables to print products with two different materials, compatible with a cheap and commonly available FFF device Prusa i3MK2S, and the subse-quent production of a prototype. A key aspect of the design was the hardware compatibility of the device with the given printer while maintaining the maximum possible printing area.

In today's manufacturing industry, composites are widely used. This is primarily due to the highly variable material properties that can be obtained by combining various materials as reinforcements and matrices. However, modern environmental concerns have pushed researchers and engineers to seek materials from organic and renewable sources. The study will look into composite surface roughness during the cutting process, which will involve milling with a CNC router machine. A portable surface roughness tester will be used to obtain a surface roughness average (Ra) reading, and microscopes will be used to examine the composite surface roughness behaviour under a microscope. Based on the results of the experiment, 82 wt.% vinyl ester resin on coconut fibre composite provides the best material properties. With a constant feed rate of 500 mm/min applied to spindle speeds of 5,000, 20,000, and 30,000 rpm, the 5,000 rpm showed the best surface roughness average performance compared to the other two. Further research focusing on feed rates may be required to better deduce the material machining data.

The aim of this work is to propose a methodology for evaluating inhomogeneity due to the sedimenta-tion of fibres in High-Performnce Concrete (HPC) mixtures. HPC mixtures makes better mechanical-physical properties than ordinary concrete. To achieve higher strengths, the fine-grained matrix is rein-forced with the reinforcement – fibres. The type of used fibres and their homogenization in mixture has an influence on the final mechanical properties of HPC mixture. Four concrete mixtures with same com-ponent proportion was chosen for experiments. Water was the only one component, that was changing in mixture recipes. Steel fibres with a ratio of the diameter to length = 0.3/20 were used as reinforcement. The fibre volume in mixture was 1.5 %. The microscopy analysis was used for evaluation of the fibre dis-tribution in the test specimens. It was obtained, that the concentration of the fibres increases with dis-tance from the surface to the bottom of the HPC structure and this non-homogeneity increases with higher water dosage. The dependence of sedimentation of fibres on composition of HPC mixtures can be used for evaluation and optimization of final mechanical properties of the HPC structures.

This study focuses on the analysis and solution of thread production in thin-walled profiles. It explores three different threading technologies, including cutting, forming, and extrusion. The issue of a screw joint in a thin-walled component is complex due to the stiffness of the joint and the short length of the thread. Hence, the careful choice of a suitable manufacturing process for producing inner threads in thin-walled components holds significant importance. The study entails monitoring the hardening of surface layers of materials after thread production, in conjunction with the acquisition of microstructure images of the experimental material. The outcome is a comparative evaluation of different individual thread production technologies.

Additive manufacturing is a relatively new technology that has recently undergone noticeable develop-ment, which includes several types of technologies based on the gradual deposition of material in layers. The most widespread method is Fused Filament Fabrication, which belongs to an extrusion technique. The typical feature of extrusion methods is material deposition in the filaments form. Therefore, printer users cannot apply the same approach to products as with conventional technologies. The authors of the paper have been working with the mentioned technology for several years. The primary goal of the research is the investigation how printing parameters affect the mechanical properties of laminates reinforced with chopped carbon fibres. Based on experience and knowledge, the authors report in this article the most common challenges encountered in the preparation process of specimens for tensile testing. This knowledge can also help ordinary users of 3D printers, who also face these challenges without being aware of the impact of these pitfalls on mechanical properties.

The main objective of the work was to describe the laboratory methods suitable for hydrogenation of free-cutting steels and to study the hydrogen embrittlement of 11SMn30 free-cutting steel. Hydrogenation and subsequent mechanical testing of hydrogenated steel is not common laboratory method as it requires precise and expensive equipment, is time consuming and dangerous as hydrogen is highly reactive and explosive. Currently, there are several theories of hydrogen embrittlement mechanisms of steels that describe the causes of material degradation by hydrogen. However, those theories are not universally valid; individual accounts have been developed and describe hydrogen embrittlement only for specific conditions and may fail in their descriptions under others. In this work, the hydrogenation of free-cutting steel 11SMn30 steel by two different methods (immersion and ca-thodic) was investigated in order to induce embrittlement and to compare in particular the fracture surfaces after the Charpy impact test. The results reported in this paper indicate that manganese sulphide inclusions are not the main cause for hydrogen embrittlement in free-cutting steels. The effect of manganese sulphide inclusions was attributed only to hydrogen trapping, that generated a high stress causing their decohesion from the matrix.

In the present work, the microstructure, crystal orientation, mechanical properties and strengthening mechanisms for different regions of WE71 cylindrical parts have been investigated. The results showed that from inner wall to outer wall, second phases density, DRX fraction decreased but average grain size increased, which is well agree with the strain state and metal flow during back extrusion. For compression area, α//ED texture type can be found in region a, but α directions deflects from ED to TD at a certain angle for region b and c. For shear area, α directions deflects from ED to TD about 10°~45°. For stable forming area, the texture is close toα//ND. After peak ageing, a large number of nanometer scaled β' phases were formed and uniformly distributed in the Mg matrix, while zigzag GP zone and RE-hexagons precipitates can also be found in the peak-aged alloy. Tensile properties for region c in compression area are the lowest: UTS, YS and EL are 322 MPa, 215 MPa and 2.5%, respectively. Furthermore, for the stable forming area, the UTS, YS and EL of 283 MPa, 187 MPa and 19% in the region f are the highest, but the strength of region g is the lowest, which is related to the grain size and volume fraction of second phases on flow lines. The strengthening contributes from fine-grain strengthening, texture strengthening and Orowan strengthening.

In the automotive industry, deep-drawn sheet metals are widely used and protective coatings are ap-plied to its surfaces to improve certain performance properties (e.g. to increase corrosion resistance). Sheets with these coatings are stressed during the forming process of the part and cracking of the protective coating may occur. The main goal of this paper is to determine the resistance of a Zn-Al-Mg based protective coating to uniaxial and triaxial stresses, and also to determine how effective anticorrosion resistance the coating provides to the base steel matrix in the event that cracking occurs. It has been shown that both uniaxial and triaxial loading leads to a failure of the Zn-Al-Mg coating integrity. Salt spray corrosion tests of 3 and 6 weeks were subsequently performed on both deformed and undeformed base material samples. These tests showed that a continuous Al2O3 layer is formed between the steel matrix and the coating, which, irrespective of the formation of cracks in the coating, is the main contributor to the increase in corrosion resistance of the sheet.

The paper considers questions asotiated with automated systems to produce composite parts. Exist-ing automated systems used in aerospace production are usually based on lay-up technologies. The main objective of the on-going development is to find an affordable production technology for com-posite parts that can be easily automated. The handling with dry reinforcing fabrics is objective of the paper: dry fabric is placed in a suitable mold where it is impregnated by selected type of a matrix and consolidated under vacuum bag afterwards. Based on experiments using standard gripping systems, it was found that local damage of reinforcing fibers occurs. For these reasons, a new vacuum suction-based gripper was developed. As a suction source industrial vacuum cleaner was used, whose perfor-mance can be regulated continuously. Functionality of the suction system was verified on six differ-ent types of reinforcing materials, using two different types of suction grid at three different levels of vacuum cleaner performance. Performed experiments verified suitability of the designed solution for manipulation with dry fabrics without the risk of their damage.

Casting with a disposable pattern is a method employed to produce intricate-shaped castings. This manufacturing technique falls into the near-net shape methods category, which ensures that the result-ing castings closely resemble the final components. Its primary application lies in industries where pre-cision and complex castings are of paramount importance. Typically, castings manufactured using this method utilize higher-cost materials. The focus of this study centres on the utilization of reverse engi-neering in the production, modification, and inspection of wax injection moulds during the casting pro-cess. Within the scope of this investigation, a non-contact method employing the Kreon arm with the Aqulion scanner was implemented. This method facilitated the generation of a digital scan, serving as the foundation for designing and validating the mould for subsequent practical application.

The growing use of composite materials in various industries implies the necessity of conducting research on both their manufacture and subsequent machining. One of the main problems in composite machining is the selection of a suitable cutting tool. This study investigates the effect of the geometry and material of a milling cutter on the quality of a milled composite part. A carbon fiber-reinforced epoxy resin matrix composite was tested. Two cutting tools were used: an end mill with PCD inserts with a diameter of 12 mm and the number of teeth of 3 as well as a PCD-coated carbide end mill with a diameter of 12 mm and the number of teeth of 4. Variable technological parameters were used. The quality of the machined surfaces was assessed based on burr height and selected profile roughness parameters. Results showed that for the milling process conducted with the same technological parameters, the surface quality obtained with the 4-tooth PCD-coated carbide tool was higher than that obtained with the 3-tooth tool with PCD inserts.

The article presents results of the use ABC method applied to technological machines modernity level assessment in anti-corrosion protection of steel structures. Research findings enables identifying and analysis of the technological modernity level of machines used in the anti-corrosion protection process that is crucial for the final quality of the process and product manufactured in the steel construction production. The paper proves effectiveness of using ABC method of the machines modernity level as-sessment in the analysis and improvement of the steel construction corrosion ensuring process.

Titanium alloys are among the biocompatible materials that are used for biomedical implants. From the point of view of the reactivity of the human body, it is important to know the state of the surface of these materials, which in technical practice is represented by the term surface integrity, which includes a complex of evaluated properties. One of the classic approaches is the evaluation of the surface roughness and the properties of the stable oxide layer, which influence the formation of the connection of the implant with human tissues and influence its acceptance. Another frequent approach is the use of optical metallography, especially for the assessment of material thickness, distribution and character of corrosion attack. Less common is the use of electron microscopy in the evaluation of the surface, which in this case is affected by the action of corrosion. Samples of both pure titanium and Ti6Al4V alloy were divided into sets according to surface roughness and subsequently exposed to corrosion for different periods of time. The presented article is devoted to basic analyzes of the effect of roughness on corrosion behavior using not only classical optical but also electron microscopy.

This article deals with the comparison of the wear of indexable CNMG carbide inserts from two dif-ferent manufacturers when turning austenitic stainless steel 1.4404, which is not intended as the pri-mary material to be machined from the point of view of the tested inserts. The main goal was to demonstrate the different course of wear by testing inserts of the same type according to ISO 6987 showing the connection between the design and processing of the inserts in connection with the se-lected cutting parameters. The monitored type of wear was the main flank wear VBmax, depending on the length of the machining time. Optical and electron microscopes were used to analyze the flank wear. According to the assumption, it was found that the layout of the cutting edge geometry and coating layers has a noticeable effect on the degree of wear of the evaluated cutting inserts. At the same time, it was found that the tested indexable inserts achieved very good service life values de-spite the fact that the tested material does not belong to the primary use group. Evaluation of cutting tool wear has a significant economic potential for manufacturing companies seeking to minimize costs by trying to use as many universal cutting tools as possible or looking for opportunities to ex-pand the applications of already used cutting tools.

Testing of machinability of the UMCo50 superalloy was carried out within the project following the actual production of the semi-finished product by casting. Turning was chosen as the machining method to minimize the effect of an interrupted cut. Considering the machinability of a hard-to-machine alloy, the cutting material with the fine-grained WC-Co carbide with the TiN/TiAlN gradient PVD coating was selected. The progression of cutting forces, chip formation and tool wear were evaluated. Images of the material structure of the semi-finished product and the resulting chips were taken. From the measured values, graphs of the dependence of the chip thickness ratio on the cutting speed and the Taylor´s dependence of the tool durability on the cutting speed were obtained. The aim of the experiment was selection and verification of suitable cutting conditions for efficient machining of this superalloy, especially the appropriate value of the cutting speed. The recommended value of the cutting speed was 50-70 m.min-1, while the tangential component of the cutting force was in the values usual for corrosion-resistant steels.

Nickel superalloys are the main materials used in manufacturing of turbine blades and vanes in aero-space industry. They works is extremely high temperature in a corrosive environment (oxidation, hot corrosion) and undergo several different thermo-mechanical loads. Aluminide coatings are the main method of protection of the surface of nickel superalloys against exhaust gasses environment in jet en-gine. In presented article the microstructural characterization of aluminide coatings produced using two industrial methods (pack cementation and out of pack was conducted. The commercially available powders manufactured by Oerlikon-Metco were used in aluminizing process using industrial Bernex BPX Pro 325S CVD system. The MAR M247 was used as a base material. Amount of activator and pure aluminum had a noticeable effect on the total thickness of obtained layers. Both samples with increased activator and pure aluminum content formed 5 to 11.5 x thicker aluminide coatings in comparison to other sample, which was aluminized using an Al-Co powder as aluminum source. Further investiga-tions are needed to specify precise phase composition of analyzed coatings.

The article deals with the possibility of increasing mechanical and utility properties by means of regenerative heat treatment. Experimental program is focused on the heat treatment of low-alloy heat-resistant steel EN ISO 14MoV6-3. This steel has been used since the 1970s for high-temperature exposed components in practically all coal-fired thermal power plants in the Czech Republic. Thus, steel EN ISO 14MoV6-3 is currently the best studied refractory material whose data, collected from experimental creep behaviour tests, exceeds the computational service time 2.105 hours. In order to remain competitive in the new energy mix, conventional steam power plants are forced to adapt to the requirements of semi-scheduled power generation. However, these plants were not originally designed for such operation and therefore have to adapt to new demands on the timing of the power provided, including requirements to reduce overall plant emissions and to increase the efficiency of power generation. These components are now subjected to substantially increased cyclic stresses due to power changes during half-cap operation. These stresses have a major impact on the material lifetime and therefore on the overall performance and lifetime of the plant.

Article presents a novel approach to addressing the challenge of forge-free filling of gas cylinder valve knobs in the context of the pneumatic shock absorber utilized within elevator systems. The shock absorber is a critical component responsible for ensuring accurate and efficient transportation of charge material to the electric inductor of automatic hot forging presses. Precise control of the shock absorber's operation is essential for maintaining proper system functionality and minimizing deficiencies. To investigate the system's response to changes in shock absorber operating parameters, the authors conducted a comprehensive simulation. The simulation results revealed that by identifying specific and optimal operational characteristics, the level of deficiencies can be significantly reduced. These findings offer valuable insights into system behavior, facilitating the optimization of shock absorber operation and overall improvement of the hot forging process. Implementation of the optimized shock absorber operation based on the simulation outcomes can enhance productivity, cost-efficiency, and quality in the hot forging industry.

This research focuses on comparing the working accuracy of two additive manufacturing processes, Atomic Diffusion Additive Manufacturing (ADAM) and Binder Jetting (BJ). Through the analysis of key characteristics of these processes, we aim to evaluate which one yields better results in terms of working accuracy. ADAM is a process that involves the gradual deposition of metallic materials using a plastic binder, whereas BJ is a process where the binder is applied to powder material, followed by the removal of excess binder. This work conducts a detailed examination of the properties of the ADAM and BJ processes, with a focus on surface texture and microstructure of the resulting objects, the use of optimal technological parameters, and the assessment of dimensional and shape accuracy. It is also important to note that the final nature of 3D objects depends on technological parameters such as geometry, orientation, and placement of individual shape specifications. The results of this study are crucial for assessing the accuracy of these additive processes and can serve as a significant basis for selecting an optimal approach in the field of additive manufacturing.

Al-Cu-Mg based alloys are often used in the automotive industry. There are characterized by high strength characteristics but poor corrosion resistance, which appears to be problematic in this sector. The manufactured blanks of these alloys may be protected by some of the barrier protection methods, including cladding. Semi-finished products made of these methods can be protected against corrosion by a thin layer of aluminium oxides - called clad Durals. The surface layer creates a stable and durable Al2O3 layer, which provides corrosion resistance, which leads to an extended service life of the piece.
However, this type of protection is adversely affected by the effect of copper diffusion, which is dependent on the heat treatment mode of the alloy. Temperature and temperature hold are the main factors influencing the diffusion process. In the solution annealing of aluminium alloys, the temperature is in the range of (470-500) ° C, resulting in intense diffusion processes at the inter phases interfacial.
The paper deals with the analysis of the influence of the heat treatment regime on the corrosion resistance of Al2024 alloy sheets (AlCu4Mg1 type alloy) provided with an Al1050 alloy clad coating on both sides in a corrosive salt mist environment in accordance with EN ISO 9227, which is supposed to have a positive effect on extending the service life of a car component.

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.

Polyvinyl butyral is a material that is widely used in the manufacture of laminated glass sheets. Polyvinyl butyral film is widely used as an intermediate layer for laminated automotive or architectural glass. The intermediate layer primarily ensures the safety function of the laminated glass. Other advantages of laminated glass with a polyvinyl butyral interlayer include that it can be adapted to perform other functions, including acoustic functions, anti-reflection functions or functions enabling information to be projected on the glass with this interlayer. In this work, the influence of further processing of polyvinyl butyral film with non-uniform thickness is studied. Further processing may have a negative impact to the profile of PVB material.

This paper focuses on the issues of tool thermal deformation during machine preheating，designing an image-processing-based solution for measuring these tool thermal deformation, to obtain the axial thermal error of the tool as a function of preheating time.This paper uses a high-speed camera to collect images of tool thermal deformation. Using MATLAB software, rough localization of images by Canny algorithm for edge extraction. Accurately locating tool edge outlines using a sub-pixel fitted edge detection method, that is, using the least squares method to fit a tool tip arc curve. From this, the thermal deformation during tool preheating is calculated. This study will serve as a basis for the compensation of thermal errors in machine tools.

After the Fukushima accident in 2011 year, ATF nuclear fuel cladding concept was accelerated to achieve the reactor operation with the new accident tolerant structural materials. However, several designed solutions do not fulfil the accident tolerant concept but particularly increase the corrosion resistance of Zr-cladding tubes at normal operating conditions, so-called “Advaced Technology Fuel, EATF”. Cr-coated zirconium claddings following the first concept, have been the widely tested and the first full Cr-coated fuel rods have been planned to operate in LWR reactor conditions around the 2022 year. Our contribution describes the Cr-coated Zr-%1Nb cladding tube microstructure after high-temperature steam oxidation at 1200°C by means of Scanning Electron Microscopy and nanoindenta-tion methods. The article is focused on WDS line-profile studies of oxygen and chromium diffusion into the Zr-matrix. The increased Cr-diffusion with oxygen is evident causing a change in local me-chanical properties which is well-described by measurements of nanohardness and Young's modulus. In addition, the developed methodology of the WDS & nanoindentation line-analyses was also opti-mized to apply in hot-cell conditions to measure the effect of neutron-irradiation on the different coat-ings and coating/matrix interface.