Nowadays additive manufacturing continues to gain more and more space in industrial technology. In particular, FDM (fused deposition modelling) machines have become easily available to the public. Quality of parts is impacted by several factors. In this study we investigate layer thicknesses of a prototype manufactured from PLA, and we pay special attention to the thickness of sequentially deposited layers.
Ultrasonic welding is a very useful and simple welding process. It is suitable for establishing a joint between thin sheets and dissimilar metals with short preparation and finish work time . Some welding defects were detected due to less than optimal ultrasonic welding parameters. These defects were ruptures, surface colour change and unacceptable deformations. This article aims to identify these failures and their causes.
Krisztián Kun, János Kodácsy, Dániel Vaczkó and Zsolt Ferenc Kovács
The subject of this research is the machining of Ni-based super alloys using indexable end mills. The cutting ability of these materials is known to be difficult, even challenging with modern tools, so our goal is to create an efficient technology recommendation on an experimental basis. To this end, we have developed an experimental design from which results are used to determine the optimal technological parameters. This research took place at John Von Neumann University, Department of Vehicle Technology of GAMF Faculty.
In this study two different types of hollow sphere were examined by mechanical, geometrical and microstructural measurements, and the fracture force, geometrical properties and chemical composition were determined. The diameter of the „01 globocer” type specimens was 2.37 mm on average, while the value for the „03 globocer” type specimens was 6.88 mm, both were smaller than the nominal diameter. The average deviation from the circularity of the 01 globocer specimens was 8 %, the value for the 03 globocer specimens was 6 %, while the average wall porosity was 53±3 % and 56±3 % respectively. The surface of the hollow spheres was uneven, which has an impact on the contact surfaces during pressure tests, which affects the fracture force values. The average value of the fracture force of 01 globocer spheres was 42 N, and of 03 globocer hollow spheres was 288 N. The diameter had a bigger impact on the fracture force values of the type 01 specimens than in the case of 03.
There has been a spectacular and extremely fast development in all areas of materials science. This development is driven by science and technology, yet a time gap may be observed between the progress of technology that drives the fourth industrial revolution, and its acceptance in society. Our task is to learn how a balance may be achieved between rapid technological development and societal acceptance.
Csaba Balázsi, Mónika Furkó, Fruzsina Szira and Katalin Balázsi
Aluminium oxynitride (AlON) has a unique thermal and chemical stability that makes it the perfect candidate for a wide range of applications. This article provides a brief description and comparison of the most common AlON preparation methods along with their advantages and disadvantages. Although there has been extensive research on the material, especially more recently because of increased commercial interest, extensive systematic powder synthesis and processing studies have not been carried out to determine alternate, more cost efficient routes to fully dense transparent bodies. Further optimization of reaction sintering and transient liquid phase sintering could be important processing routes.
The laser processing of materials which are highly reflective at laser wavelengths is problematic. We have to take into account that only a small part of the energy is absorbed, the main part being reflected. In this article we examine the laser processing of highly reflective copper and silver at 1070 nm wavelength. In laser drilling of printed circuit boards it is necessary to drill copper layer as well. In highly reflecting materials we can drill smaller holes because of the low energy efficiency. Naturally in single pulse laser drilling the focus position plays a key role: at the focal spot of the laser beam smaller diameter holes are produced, further from the focal spot, higher diameter holes are produced.
This article deals with the vibrations of a nonprismatic thin-walled beam with an open cross section and any geometrical parameters. The thin-walled beam model presented in this article was described using the membrane shell theory, whilst the equations were derived based on the Vlasov theory assumptions. The model is a generalisation of the model presented by Wilde (1968) in ‘The torsion of thin-walled bars with variable cross-section’, Archives of Mechanics, 4, 20, pp. 431–443. The Hamilton principle was used to derive equations describing the vibrations of the beam. The equations were derived relative to an arbitrary rectilinear reference axis, taking into account the curving of the beam axis and the axis formed by the shear centres of the beam cross sections. In most works known to the present authors, the equations describing the nonprismatic thin-walled beam vibration problem do not take into account the effects stemming from the curving (the inclination of the walls of the thin-walledcross section towards to the beam axis) of the analysed systems. The recurrence algorithm described in Lewanowicz’s work (1976) ‘Construction of a recurrence relation of the lowest order for coefficients of the Gegenbauer series’, Applicationes Mathematicae, XV(3), pp. 345–396, was used to solve the derived equations with variable coefficients. The obtained solutions of the equations have the form of series relative to Legendre polynomials. A numerical example dealing with the free vibrations of the beam was solved to verify the model and the effectiveness of the presented solution method. The results were compared with the results yielded by finite elements method (FEM).
Nanostructured CdO thin films have been prepared on glass substrates by spray pyrolysis technique using perfume atomizer from fresh and aged (1, 2, 3 and 4 days) precursor solutions. XRD studies confirm that all the films exhibit cubic crystal structure with a (1 1 1) preferential orientation. The preferential orientation factor f(1 1 1) increases with an increase in aging the period of precursor solution. The 2θ value of the (1 1 1) plane shifts towards lower Bragg angles with aging inferring an expansion in the lattice volume of the aged films. Increased crystallite size is observed for the 3-days aged film for which minimum strain and dislocation density values are obtained. Optical transparency increases with an increase in aging period of the precursor solution and the optical band gap exhibits a red shift from 2.48 eV to 2.32 eV. Minimum resistivity of 0.78 × 10−2 Ω·cm is observed for the CdO film prepared from 3-days aged solution. The obtained results infer that the CdO film prepared from 3-days aged solution exhibits better physical properties than the others.