Mechanical Engineering

Additive technologies have been widely adopted in various industries. The choice of additive technology and material directly affects the functionality of the manufactured components. The development of materials with better mechanical properties has led to a growing interest in replacing traditional metal components with those manufactured using additive technologies. The application of Onyx as a material comes into consideration, which contains short carbon fibers to increase the mechanical properties. This study aims to experimentally verify the viability of substituting metal gripping elements with nylon and composite materials. The design of the jaws was customized to meet the requirements of a three-jaw chuck of a CNC machining center. The evaluation process involved monitoring the functionality and deformation effects on the clamped PTFE polymer material. When the metal jaws were applied, significant deformation of the clamped material occurred, which varied with the clamping...

The presented article focuses on the analysis of the components manufactured by different additive technologies and their reverse digitization. Sintered components were manufactured by Selective Laser Melting (SLM) and Atomic Diffusion Additive Manufacturing (ADAM) technologies. ADAM can be classified as indirect additive production using fibre of metal powder bound in a plastic matrix. SLM method works on the basis of selective bonding of metal powder using the thermal energy of the laser beam. The components were manufactured from anti-corrosion materials 17-4 PH and 316L-0407. In the experiment, parameters such as dimensional and shape accuracy were verified using laser scanning. Next, the roughness of the printed surfaces was measured on an Alicona Infinite Focus 5G optical measuring device. The dimensional accuracy of the ADAM process was evaluated using ISO IT grades. The accuracy of ADAM technology achieves the IT13 grade that is comparable to that of traditional processes for the production of semi-finished metal parts. Additive manufacturing Sintering Optical scanning 17-4 PH 316L-0407 SLM Surface texture

This paper will investigate the changes in size and amount of the microstructural features in secondary aluminium casts associated with different wall thickness. The experimental samples were casting into the sand mould. The changes were documented and assessment by using optical microscope and methods of quantitative analysis. The results shows that increasing wall thicknes lead to formation larger second phases and coarsening of the matrix, which lead to decreasing mechanical properties.

Additive manufacturing has recently expanded its potential with the development of selective laser melting (SLM) of metallic powders. This study investigates the relation between the mechanical properties and the microstructure of Ti6Al4V alloy produced by SLM followed by a hot isostatic pressing (HIP) treatment. HIP treatment minimizes the detrimental influence of material defects. Tensile specimens produced with reference to specific building axes were prepared using a Renishaw A250 system. It has been found that the tensile strength and elongation depend on specimen building direction. Microstructural and textural characterizations were carried out to identify the source of differences.

Recycled (scrap-based) aluminium alloys are commonly referred to as secondary. In cast aluminium components, brittle and needle/plate-like Fe-rich particles are common constituents that normally degrade the mechanical properties. Secondary Al-alloys contain higher background Fe levels than the primary metal and is currently no economical way of removing Fe. Therefore, it is important to gain knowledge on the effect of Fe-rich particles on mechanical properties in order to expand the use of more environmental friendly secondary alloys. Present study examines the effect of iron phases Al 5 FeSi in secondary self-hardening AlZn10Si8Mg cast alloys A (0.15 wt% Fe) and B (0.56 wt% Fe) on microstructure, mechanical properties (UTS, YTS, ductility and Brinell hardness) and fracture surfaces. For observation and identification of microstructural components as Si and Fe-phases standard (0.5% HF) and deep etching (HCl) were utilized. The results showed that the eutectic silicon in alloy B has a slightly finer structure (probably due to slightly higher cooling rate used); with increasing of the Fe content, the length and number of Al 5 FeSi phases increased too; mechanical properties slightly decreased (YTS from 175 MPa to 166 MPa and UTS from 187 MPa to 178 MPa). The fracture surface of experimental samples mainly consists of transcrystalline ductile fracture (the transcrystalline cleavage fracture was not detected as much). In alloy A dominant is the transcrystalline ductile fracture in the eutectic and on the a-matrix and in alloy B is dominant the transcrystalline cleavage fracture.

Secondary-cast aluminum alloys have increasing industrial applications. Their biggest deficiency is their impurity content, especially Fe, which has low solubility in Al and almost all the content creates intermetallic phases. This work examines the effect of higher Fe content on the microstructure and properties of A356.0 alloy. At the same time, no other possibility existed to affecting the brittleness of the formation of the β phases. The calculation of Fecrit, ratio of Mn/Fe, quantitative and computed tomography analysis of porosity and Fe plate-like phases, measurement of mechanical and fatigue properties, and fractography analysis were performed in this study. The results show that gravity die casting into a sand mold, and the non-usage of Mn addition or heat treatment, do not have a negative effect on increasing the size of the Fe-rich plate-like phases. The longest Fe-rich phases have limited the pore growth and ratios, but their higher thickness led to greater porosity form...

Peer-review under responsibility of the scientific committee of the TRANSCOM 2021: 14th International scientific conference on sustainable, modern and safe transport 14th International scientific conference on sustainable, modern and safe transport

This study deals with the research on the impact of the construction of a tire-building drum on the selected parameters of a passenger tire. The introductory part of the study deals with a comprehensive analysis of the production process and factors that affect the quality of the final tire product during production. The content of this analysis is also the naming of problematic parts and their subsequent influence on the resulting parameters of a passenger tire. The core of the study is an optimization design for improving the construction of the tire-building drum. The world-renowned TRIZ methodology was applied to achieve the desired improvement results. Using the TRIZ methodology, the technical system was analysed, identified problematic parts, and defined the technical and physical contradictions and proposed possibilities for their removal. The systematic approach to the solution of the task has generated options for the right solution and possible optimization by reducing the...

The article is focused on the analysis of the structure and fracture surface of aluminum alloy specimens. Aluminum alloy AlMg9 was mainly used as an experimental material. The material from which specimens were made was supplied as cast without heat treatment, and specifically the material was produced by the continuous casting method. The structure of the test material was examined using a Neophot 32 optical microscope, and the fracture surface of the test specimen was examined using a scanning electron microscope (SEM). The fatigue life of the aluminum alloy was tested by method of a three-point bending cyclic loading using the parameters-frequency f = 100 Hz, temperature T = 22 ± 5 ℃ and stress ratio R = 0.11. The analysis showed that cast aluminum alloys are very sensitive to casting defects, such as porosity or the content and distribution of intermetallic phases. If large pores or phases are present on or near the surface of the sample, this can be the dominant cause of fatigue crack initiation and reduction of the fatigue lifetime. Aluminum Alloy Fracture Surface Structure Fatigue Bending Loading